UWORLD BIOLOGY

Muscle force development is initiated by a series of events that occurs in response to muscle fiber membrane depolarization.

. This series begins with detection of depolarization by a receptor located in sarcolemmal tubes (called t-tubules) that penetrate deep into the muscle fiber. In response to this depolarization, Ca2+ is released from the sarcoplasmic reticulum (SR) through a Ca2+ channel in the SR membrane. The resultant rise in cytosolic Ca2+ leads to binding of Ca2+ to a specific type of troponin molecule, and this troponin molecule in turn enables stronger binding of the myosin head to actin. This stronger binding enables myosin to pull on the actin filament, thereby generating tensio

An operon is composed of three elements

1. A promotor or the upstream region of DNA to which RNA polymerase and other transcriptional modulators binds 2. An Operator , which is a nucleotide sequence, either within the promotor or between the promotoer and the downstream genese regulated by the promotor to which the repressor binds 3. the genes controleld by the operon notes Transcription factors (i.e repressors) bind the the promotor region of the genes they want to regulate.

The number of cells that result after incubation can be calculated as follows

1. Calculate the amount of time in which the bacterial population was in log phase. i.e 180 min incubation time - 20 min lag phase == 160 min log phase. 2. Find the number of generations in the log phase period 160 min log phase/40 min generation time = 4 generations 3. Multiple the original number of bacterial cells by 2^n to get the final population size 5 bacterial cells * 2^n = 80 cells generation time refers to the time in which a bacterial population doubles when a single cell divides by binary fission, the number of cells that results is calculated by multiplying the original number of bacterial cells by 2^n where n equals the number of generations

Nutrient absorption in the gastrointestinal tract is influenced by several factors i.e

1. Fatty acid producing bacteria in the large intestine ---> metabolize undigested carbohydrates form the small intestine into short chain fatty acids which are absorbed and used as additional energy sources. 2. Small intestine surface area. Large folds in the intestines epithelial lining slows the movement of chyme through the intestinal tract. 2b. Also has villil which maximize the time and surface area available for nutrient absorption 3. Intestinal proteins --> structural proteins, digestive enzymes, and nutrient transporters work synergistically to break down and absorb nutrients within the gastrointestinal tract.

The role of PTH is to maintain an adequate calcium concentration in the blood, a task it accomplishes primarily by stimulating three processes

1. intestinal absorption of calcium from the diet 2. reabsorption of calcium filtered by the kidney (i.e reducing urinary calcium loss) 3. promoting release of bone calcium into the blood resorption of bone by osteoclasts in stimulated indirectly by PTH via osteoblasts. PTH promotes production of osteoblasts, as well as osteoblast release of ligands that PROMOTE DIFFERENTIATION OF OSTEOCLAST PRECURSOR CELLS INTO OSTEOCLASTS. with prolonged exposure to elevated PTH concentrations in the blood, osteoclast numbers increase leading to increased bone resorption.

The sequence of amino acids in proteins is encoded by nucleotide triplets in mRNA and the four conventional RNA nucleotides are distinquished by their different bases (adenosine, guanine, cytosine and uracil) and provide

4^3 conventional nuceltodie combiantions

To repair Double Strand Breaks: What needs to occur?

A deoxyribose sugar and a phosphate on both DNA strands must bind (i.e via phosphodiester bonds. This binding rejoins the breaks in the DNA double helix.

Telomerase

A reverse transcriptase that synthesizes telomeric repeat sequences at the ends of chromosomes from its own RNA template.

Hypothalmus secretes CRH which then induces the ant pit gland to release

ACTH and then ACTH stimulates the adrenal glands to synthesize and secrete the glucocorticoid hormone cortisol.

Open Reading Fram

AUG

Blood initially enters the kidneys through the renal arteries, which separate into smaller, afferent arterioles that carry blood toward the nephrons

Afferent arterioles then branch into a ball-like network of capillaries known as the glomerulus. The glomerulus itself is surrounded by a nephron component called the Bowman's capsule that collects leaked glomerular fluid (ie, renal filtrate). The blood then exits the glomerulus through the efferent arterioles. Efferent arterioles later branch into a second series of capillaries that encapsulate the remaining portions of the nephron, facilitating the movement of components out of the filtrate and into the blood, or vice versa

All cells in an organism posses identical genomes

All cells that comprise a multicellular organism contain identical genomes. These cells can differentiate (ie, specialize in structure and function) during development through differential regulation of gene expression.

Antiduretic hormone

Antidiuretic hormone is released from the posterior pituitary to promote water reabsorption by the kidneys when blood pressure falls.

Prokaryotic organisms such as bacteria can be classified by their shape, or morphology. The morphology-based classification of bacteria involves three basic shapes:

Bacilli are rod-shaped bacteria. Cocci are spherical bacteria. Spirilli are spiral bacteria.

Eukaryotic Organisms are classified into the Eukarya domain, but prokaryotic organisms are in either the

Bacteria or Archae domain. Organisms classfied as archae share traits w/ bacteria. Like abcteria, archae are unicellular, have a circular chromosome, have no membrane bound organells or nucleus and reproduce asexually via binary fission. HOWEVER UNLIKE BACTERIA, ARCHAEA DO NOT HAVE THE CHEMICAL PEPTIDOGLYCAN IN THEIR CELL WALLS.

Anti-nAChR antibodies

Based on the passage, anti-nAChR antibodies bind nAChR reversibly to block the interaction between ACh and nAChR, resulting in muscle weakness. Accordingly, administration of these antibodies in a wild-type mouse would temporarily prevent binding of ACh to its receptor. Consequently, the unbound Ach in the synaptic cleft of these wild-type mice would likely be degraded before being able to bind nAChR, decreasing muscle contraction. However, if a mutant mouse were to exhibit normal muscle contraction despite being treated with anti-nAChR antibodies, a likely explanation could be that ACh degradation within the mutant's synapse is decreased compared to that of the wild-type. Decreased ACh degradation would increase the number of ACh molecules available to bind nAChRs after these receptors are no longer bound by anti-nAChR antibodies. This would likely allow muscles to eventually exhibit normal contraction despite the presence of anti-nAChR antibodie

All aging RBCS are eventually destroyed by phagocytic cells (i.e macrophages in the spleen.

Because RBS with wild-type hemoglobin woudl eventually be destroyed, the patient would require multiple blood transfussions

DNA replication(synthesis) occurs during S phase of the cell cycle and precedes mitosis

Because of proofreading, DNA replication is generally unlikely to introduce errors (i.e mutations) and is therefore less likely source of genetic variation than crossing over.

Fluid and Lipid Transport Through the Lymphatic System

Blood flows through capillaries --> some fluid containing plasma proteins leak out of the blood vessel and into the interstitial fluid interstitial fluid fills the space between blood vessels and surrounding cells leaked excess fluid from the capillaries now also known as interstitial fluid must be returned to the bloodstream to maintain the proper blood volume and protein concentration. to reenter the bloodstream, the fluid must first pass form the interstitial space and enter a network of vessels and noes known as the lymphatic system. Once in the lympathic system, the fluid is known as LYMPH and is ultimately drained into two large veins near the heart. Lymphatic system also collects large lipid droplets absorbed by the small intestine. Certain lipids digested into the small intestine are absorbed by intestinal epithelial cells and packaged into large droplets. However their large size prevents them from cross directly into the capillaries surrounding intestinal cells. Instead these lipid droplets are transported through the lymphatic system and into the bloodstream as follows: 1. Lipid droplets are released from the epithethial cells into the interstital fluid. 2. Lymph capillaries collect lipid droplets from the interstital fluid. 3. Lymph containing the lipid droplets then flows from the lymph capillaries into increasingly larger lymph vessels. 4. Lymph is then transported into a large tubule called a lymph duct which drains into a large vein near theheart. AS a result the lipid droplets within the lymph enter the blood stream and circulate throughout the body.

Divisions of the CNS

CNS and PNS PNS: Sensory vs Motor MOTOR: Somatic vs Autonomic Sensory (afferent): sensory nerve fibers transmit impulse to the CNS Motor (efferent): Motor nerve fibers transmit impulses from CNS to peripheral tissues. Somatic: motor nerve fibers transmit impulses from CNS to skeletal muscles Autonomic (involuntary nerve fibers transmit impulses from CNS to cardiac/smooth muscles and glands)

Cortisol inhibits the

CRH release from the hypothalmus and accth release from the pituitary gland. By inhibiting the secreteion of CRH and ACTH, secreted cortisol increases negative feedback such that adrenal cortex recesives less stimulatory input and the synthesis and secretion of additional cortisol decrease.

Phagolysosome: how does it work?

Certain immune cells (eg macrophages) engulf pathogens inside a vesicle in a process known as phagocytosis. When such a vesicle fuses w/ a lysosome, a digestive phagolysosome is formed. Within the phagolysosome is an acidic environment (low pH) containing enzymes that break down engulfed molecules and produce damaging reactive oxygen species that help kill or destroy pathogens.

Phagolysosome

Certain immune cells (eg, macrophages) engulf pathogens inside a vesicle in a process known as phagocytosis. When such a vesicle fuses with a lysosome, a digestive phagolysosome is formed. Within the phagolysosome is an acidic environment (low pH) containing enzymes that break down engulfed molecules and produce damaging reactive oxygen species that help kill or destroy pathogens.

In this scenario, dehydration is caused by frequent loose stools in affected individuals. Loose (watery) stools may be due to decreased water absorption or increased water secretion in the intestinal tract.

Chloride (Cl−) secretion from intestinal epithelial cells would increase the osmotic pressure of intestinal contents, drawing more water into the intestine and increasing the water content of stool. Therefore, drugs inhibiting luminal secretion of Cl− would likely decrease water secretion into the intestine and make the stools less watery

Transcription Factors

Collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription.

Peroxisomes

Contain oxidase enzymes that detoxify alcohol, hydrogen peroxide, and other harmful chemicals

Transformation is the uptake of

DNA from the extracellular fluid surrounding the cell not RNA

Missmatch repair system

DNA mismatch repair (MMR) machinery, in which a nuclease enzyme excises the erroneous nucleotide, as well as several nucleotides flanking either side of the incorrectly matched base, from the daughter strand. DNA polymerase then incorporates the appropriate nucleotides, and DNA ligase catalyzes the formation of new phosphodiester bonds to seal the gap between the strands.

Eosinophills

Defend against parasitic infections and modulate immune response during allergic reactions

Innate Immune System

Divides into Physical Barriers: Skin/Mucous Membranes/Stomach ACid Immune Cells: Phagocytic Cells (Macrophages) which nonspecifically engulf and destroy foreign pathogens and Chemical Releasing Cells: Basophils, Natural Killer Cells that enhance the immune response and promote pathogen destruction

voltage gated potassium channels

During APs, the membrane potential of the neuron changes due to opening and closing of voltage-gated sodium (Na+) and potassium (K+) ion channels as follows: At rest, a neuron maintains a potential difference known as the resting membrane potential (RMP) of approximately −70 mV, meaning that the intracellular space is 70 mV more negative than the extracellular space. The RMP is maintained by the Na+/K+ pump and K+ leak channels, or channels that are always open and allow passive diffusion of K+ across the membrane. f a stimulus causes voltage-gated Na+ channels to open, Na+ will rush into the cell, causing the membrane to depolarize (ie, the membrane potential becomes more positive). If this depolarization is enough to reach a certain threshold, an AP is initiated in the neuron. If the threshold is reached, voltage-gated Na+ channels remain open, causing further rapid depolarization of the membrane. Na+ entry causes the AP to reach its peak (overshoot), or the point at which the membrane potential is at its most positive level. At this point, voltage-gated Na+ channels close and voltage-gated K+ channels open to begin the return to RMP. K+ rushes out of the neuron, resulting in repolarization. Because voltage-gated K+ channels close more slowly than voltage-gated Na+ channels, the membrane potential briefly becomes more negative than the RMP (ie, hyperpolarization). Because voltage-gated K+ channels close more slowly than voltage-gated Na+ channels, the membrane potential briefly becomes more negative than the RMP (ie, hyperpolarization).

In contrast, a mature egg and sperm are both haploid (1n), meaning that each contains 22 (unpaired) autosomes and 1 sex chromosome, resulting in 23 chromosomes.

During fertilization, the egg and sperm form a zygote with a nucleus containing the full complement of 46 chromosomes. These 46 chromosomes are found in pairs, and in each pair one chromosome comes from the mother and one comes from the father. Accordingly, egg and sperm cells are similar in ploidy because they both are haploid cells and contribute the same number of nuclear chromosomes to a zygote.

endoskeleton vs exoskeleton

Endoskeleton: Skeleton/protection/structure inside body Exoskeleton: Shell/protective outer layer

Three major layers of the skin. Explain the parts of the skin

Epidermis --> Divided into 5 additional strata. - EPIdermis has EPIthelial tissue - Merkel cells, Langharans cells, melanocytes and keritonocytes are all found in the pidermis DERMIS - Connective Tissue!! - Blood vessels, hair follicles sensory receptors, sweat and oil glands are found. - Papilary dermis: Skin Flexibility - Reticular Dermis: Skin Strength Hypodermis - Adopose tissue!! and loose connective tissue Protects the internal organs by acting as both thermal insulator and a shock absorber.

Fast-twitch fibers achieve more rapid contraction rates (complete more contractile cycles) than slow-twitch fibers because they can hydrolyze ATP much faster. These fibers are classified as follows:

Fast glycolytic (type 2X) fibers rely primarily on nonoxidative (anaerobic) glycolysis for ATP production. Accordingly, these fibers fatigue more easily due to the acidosis caused by H+ accumulation from anaerobic ATP hydrolysis. Because type 2X fibers generally contain very few mitochondria and require much less oxygen than oxidative fibers, they exhibit low myoglobin concentration and less extensive capillary networks. Fast oxidative-glycolytic (type 2A) fibers use both oxidative (ie, aerobic respiration) and nonoxidative processes (ie, anaerobic glycolysis) to generate ATP, making them moderately susceptible to fatigue. Like type 1 fibers, these fibers also receive oxygen from abundant myoglobin reserves and extensive capillary network

During periods of stress, hormones secreted by the adrenal gland influence energy metabolism by promoting energy utilization and inhibiting energy storage. Hormones secreted by the adrenal gland regulate energy metabolism how:

Glucocorticoids: release by the adrenal cortex act on the liver to stimulate the synthesis of glucose from other molecules (GUCONEOGENSIS) and breakdown of fatts into fatty acids (lipolysis). Both glucose and free fatty acids are forms of cellular energy that can be readily utilized. Norepinephrine and epinephrine: released by the adrenal medulla and modulate the metabolism of glycogen, the storage form of glucose. Both hormoones promote glycogenolyiis. I.e inhibit glycogensis.

Helpter T cells effects on Immune Cells

Helper T cells release cytokines

T - lymphocytes bind foreign antigens found on cell surfaces and include:

Helper T-lymphocytes produce signaling molecules called cytokines that activate other cells of the immune system and enhance immune cell activity. Cytotoxic T-lymphocytes cause apoptosis to occur in pathogen-infected cells.

The cell cycle is broadly divided into two phases: interphase and the mitotic (M) phase.

Interphase consists of two gap phases (G1 and G2) separated by a synthesis (S) phase. During G1, cells grow, produce organelles, and assemble molecular machinery. In the S phase that follows, DNA is replicated. Cells then enter G2, during which cells continue to grow M phase consists of mitosis and cytokinesis. During mitosis (which consists of prophase, metaphase, anaphase, and telophase), identical sets of chromosomes are segregated into two nuclei. Afterward, the cell membrane divides to allow the formation of two daughter cells (ie, cytokinesis).

Testosterone, a hormone that stimulates sperm cell differentiation, is secreted by _____ or endocrine cells found in interstitial tissue surrounding the seminiferous tubules.

Leydig cells

peritoneum

Lines the abdominal cavity and is made of two tissue layers. The first layer is known as the parietal layer, which lines the abdominal wall. The visceral layer, in contrast covers many organs of the abdominal cavity. The peritoneal cavity is the space between these two layers. It is described as potential space, or an area between two structures that are adjacent and may be pressed against one another.

The cardiac output is the same as

Mean Arterial Pressure/Vascular Resistance

Fluid Mosiac Model

Membrane of Animal Cell is described by the Fluid Mosaic Model Transmembrane proteins and other components reside in the fluid bilayer composed largely of phospholipids. The cell membrane is said to be fluid as its various non phospholipid components can migrate laterally (from side to side) through the entire phospholipid rich surface of the cell in any direction. Other components include cholesterol, glycoproteins and glycolipids (proteins and lipids that have been modified w carbohydrates).

Cell Cycle

Most cells in the human body are arrested in G0. However, cellular transition into G1 prepares a cell for division and DNA synthesis (S phase). In the G2 phase, DNA is checked for errors and the cell ensures that sufficient organelles and cytoplasm are available for cell division. Subsequently, the cell divides in the M phase via mitosis and cytokinesis. Compounds that inhibit cell division typically target the cell cycle in phases G1 to M.

Are proteins filtered across the stomach lining?

Nope! Although proteins do undergo chemical and mechanical digestion.

Charged nad Uncharged TrNA can be measured via

Northern Blotting which is a technique for separating and quantitating specific RNA molecules

Bone remodeling is a continuous process in which osteoclasts (bone-resorbing cells) break down old bone and osteoblasts (bone-depositing cells) secrete new bone matrix. This process functions to maintain the strength and integrity of bone over time.

Osteoblasts promote the precipitation of calcium and phosphate from the bloodstream and their transfer and incorporation into the bone matrix. In contrast, osteoclasts secrete acid proteolytic enzymes and acid that break down the mineral components of bone, releasing calcium and phosphate into the bloodstream.

A gene may be inserted into a plasmid through the following steps:

Plasmids—small, circular DNA molecules—are commonly present in bacteria but are also found in some eukaryotic cells. Bacteria can exchange plasmids naturally through conjugation. Artificial plasmids are commonly used in laboratories to amplify or express a gene of interest. A gene may be inserted into a plasmid through the following steps: Digest the plasmid with restriction enzymes that cut only the plasmid at the multiple cloning site. If two restriction enzymes are used, any nucleotides between the two cut sites will be removed from the plasmid. Digest the gene of interest with the same enzymes as the plasmid to ensure that the plasmid and the gene will anneal to each other. PCR may be necessary to introduce cut sites into the ends of the gene. Incubate the digested plasmid and the digested gene together, along with DNA ligase to link them.

Prokaryotic and Eukaryotic Mechanisms that increase genetic diversity

Prokaryotic Cells - Transformation: uptake of new DNA from the environment - Transduction : viral mediated transmission of new DNA into cells - Conjugation: transfer of DNA between cells via cell to cell contact Eukaryotes: - Meiotic cell division: chromosomal cross over and random assortment of chromosomes into gametes - Fertilization: Joining of genetically unique gametes (Eggs and Sperm) Both Eukaryotes and Prokaryotes: - DNA Mutations (many types exist) - Transposition: movement of DNA segments throughout the genome

Mitsosis is the division of the nucleus and chromosomes in the cell cycle and it consists f four pahses

Prophase: condensation of chromatin and nuclear envelop disintegrates Metaphase: chromosomes align on the metaphase plate (central region of the dividing cell) and becomes attached to spindle fibers. Anapahse: in which shortening of spindle fibers causes sister chromatids to separate and migrate away from one anotehr Telophase: chraccterized by reversal of condensation of chromatin and nuclear envelope formation

The endoplasmic reticulum a cytostolic organelle compoased of a network of membranous tubules is located near the nucleus and is present in all human cells except

RED BLOOD CELLS AND SPERMATOZOA

Secretory pathway

Rough ER -> Golgi -> secretory vesicles -> cell exterior THINK PROTEIN PROCESSING

Also some reflexes do not require brain input and are regulated soley by spinal cord neurons

Sensory receptors (specialized nerve endings) detect a stimulus (eg, chemical, pressure). The stimulus activates the sensory neuron, which sends an afferent signal (ie, electrical impulse) toward spinal cord integration centers (regions that process sensory and CNS input). Within the integration center, the signal may be passed directly to an effector neuron or to an interneuron that relays the signal to the effector neuron. For supraspinal reflexes, interneurons can also relay sensory signals to the brain and integrate brain signals to regulate reflex responses. The activated effector neuron generates an efferent signal that travels from the spinal cord to the target tissue (eg, muscle), which carries out the appropriate response

X lined Recessive Inhertiance

Sex-linked traits arise due to the expression of alleles present on an organism's sex chromosomes. Because the X chromosome contains significantly more genes than the Y chromosome, the majority of sex-linked traits are linked to the X chromosome. Due to sex determination, male offspring (XY) receive their X chromosome from their mother (XX) and their Y chromosome from their father (XY). Because males have only one X chromosome and cannot compensate with another, males in a population generally express recessive X-linked traits in higher proportions than their female counterpart

MHC-antigen complexes are transported to the surface of the B lymphocyte and integrate into the cell membrane, allowing antigen fragments to be displayed outside the cell and presented to other immune cells known as helper T cells. On binding antigens presented by B lymphocytes, helper T cells release cytokines (signaling molecules) that stimulate B lymphocyte proliferation (Choice B). This produces many identical B lymphocytes that may differentiate into either of the following cell types:

Short-lived plasma cells secrete antibodies during the immediate immune response (Choice A). Long-lived memory cells remain in lymphoid tissues for a long time and can recognize the antigen more rapidly in the event of a future infection

Dipeptidases

Site of Secretion: Intestinal Glands Site of Function: SMall Intestine Function: Hydrolyze the peptide bond of dipeptides

Para/Sympathetic impact on eyes

Sympathetic activation causes contraction of radial muscles that dilate the pupils. This dilation allows more light to enter the eye in low light or periods of arousal or stress and narrows the distance range that is in focus at any one moment. Parasympathetic activation causes the circular muscles of the iris to contract, thereby leading to pupil constriction. This constriction allows for clearer vision over a greater distance range. Therefore, parasympathetic nerve activity precedes changes in pupil diameter, and the two variables are inversely correlated.

negative selection

T cells initially produced in the bone marrow are transported to the thymus, a specialized lymphoid organ facilitating T cell maturation. Within the thymus, negative selection eliminates any T cells that recognize self-antigens (ie, molecules produced by healthy cell

The thyroid gland releases

T3 and T4 which are two hormones that influence the function of most cells in the body

Telomeres

Telomeres are noncoding DNA sequences that protect the rest of the chromosome from degradation by being slowly degraded themselves. If telomeres encoded proteins, some of the coding information would be lost each time the cell replicated, which would be harmful to the cell. For this reason, telomeres do not encode any proteins (

Dermis

The dermis is composed of connective tissue and contains sensory receptors, blood vessels, hair follicles, and sweat and sebaceous glands.

Lymphatic System

The lymphatic system is a network of vessels that collect and transport lymph, ultimately draining this fluid into the bloodstream. The lymphatic system is particularly important to the immune response and includes the following lymphoid tissues and organs, which facilitate immune cell proliferation and function: Bone Marrow ---> Production of RBC and WBC from hematopoietic stem cells. Thymus --> receives T lymphocytes and facillitates their maturation ( t lymphocytes that promote self antigens die). Lymph nodes --> filter lymph as it flows through the lymphatic system. Macrophases housed within lymph nodies inditify variety of pathogens in lymph and attack. B lymph and Tlym bind specific forein antigens and induce immpunse systems. Spleen -> Blood filtration. WBC in spleen recognize and bind forein antigens in blood.

plasma membrane

The plasma membrane, also called the cell membrane, is the membrane found in all cells that separates the interior of the cell from the outside environment. In bacterial and plant cells, a cell wall is attached to the plasma membrane on its outside surface

POSTERIOR PIT HORMONES are released from NEURONS into the Blood that leaves the post pit. Explain

The posterior pituitary is a storage site for neurohormones (ie, hormones released from neurons rather than from typical glandular endocrine cells) produced by hypothalamic neurons whose axons extend down into the posterior pituitary. When stimulated, these neurohormones are released by exocytosis from the axons into the small blood vesselsthat carry blood away from the posterior pituitary. Posterior pituitary hormones are made in the hypothalamus and stored within axons projecting into the posterior pituitary. When stimulated, these axons release the stored hormones into the blood vessels leaving the posterior pituitary.

Three accessory glands are responsible for seminal fluid production.

The seminal glands produce the largest portion of seminal fluid whereas the prostate gland produces fluid containing enzymes necessary to prevent sperm coagulation within the vagina. The bulbourethral (Cowper's) glands produce a thick, alkaline mucus that lubricates the penis tip and protects sperm from the acidic environment in the urethra during ejaculation

Composition of The Two Pit Lobes

The two pituitary lobes are both derived from embryonic ectodermal tissue but differ in composition. The anterior pituitary is derived from epithelial cells from the developing roof of the mouth and contains typical glandular endocrine cells, whereas the posterior pituitary is derived from ectodermal neural tissue in the developing brain and does not contain typical glandular endocrine cells.

Stop Codon

UAA, UAG, UGA

Renal clearance is

a measure of the ability of the kidneys to remove substances from the bloodstream to be excreted

in Alternative Splicing

a single gene transcript is processed to produce various mRNA molecules that encode different proteins, depending of exclusion of particular axons. ALT splicing increases protein diversity, but does not increase GENETIC VARIATION because the genome is not altered

One method of treating genetic mutations is gene therapy

a technique in which a functional gene is introduced into a patient's cells to replace a mutant gene. The new gene can then be transcribed and translated into functional proteins. A common gene therapy method uses retroviral vectors to insert functional gene copies into the stem cells of patients exhibiting specific genetic mutations. i.e

Calcitrol

active form of vitamin D and stimulates intestinal calcium absorption

Y chromsomes alleles preent at lowest numbers thus is more suceptible to complete loss by random chance

aka genetic drift Genetic drift refers to random genetic changes in allele frequency that are due to chance events (not natural selection). Compared to large populations, small populations are more susceptible to allele loss via genetic drift.

Microtubles

alternating alpha and B tubulin subunits that assemble into hollow tubes micotubules: mitotic spindle, cell motality as the form the core of cilial and flagella transport of vesicles centrosomes and the centrisomes consists of two smaller entities called centrioles and microtubules radiate out from this organelle toward the plasma membrane

Northern blots

asess gene expression not gene count

Phagocytosis

cell eating cell enguls external particles by extending portions of their membranes to reach around the particle rather than nby the inward budding of the membrane.

Water insoluable horones (steroid hormones) diffuse across the plasma membrane and bind to

cytostolic receptors

ELISA

enzyme-linked immunosorbent assay

Chromatin exists in two forms

euchromatin and heterochromatin

For a drug to trigger an increased secretion of norepinephrine or epinephrine by the adrenal medulla, the drug must

generate effects that mimic the activity of the sympathetic nervous system

Types of Tissue

lthough connective tissue comes into contact with muscle tissue, muscle is not considered to be a type of connective tissue

mitochondria are organelles that carry out sevral metabolic processes, they are not generally connected to microtubules so the endosomes do not travel toward

mitochondria

Both eukaryotic and prokaryotic organisms catabolize glucose to produce ATP via cellular respiration or fermentation. Both metabolic processes start with glycolysis, a process occurring in the cytosol in which a single molecule of glucose is broken down into two pyruvate molecules.

prokaryotic cells (ie, bothbacteria and archaea), which do not possess membrane-bound organelles (eg, mitochondria), perform the Krebs cycle in the cytoplasm and have ETCs located on their outer PMs

Homologous chromosomes can exchange genetic information in a process called crossing over, or recombination, during____

prophase I of meiosis. Crossing over can produce new combinations of alleles within a chromosome by moving some alleles of the maternal copy to the paternal copy and vice versa. New combinations of alleles are called recombinant, whereas combinations that already existed in the parent are called parental.

Trophic hormones vs Direct

regulate the secretion of other hormones by acting on endocrine glands Direct or non-tropic hormones act directly on non-endocrine tissues to cause physiological end points (ADH - induced water rebsorption i.e) The ant pituitary releases both tropic (FSH, LH, ACTH, TSH, GH) and direct (GH, Prolactic and Endorpins). Posterior pit releases only direct hormones (oxytoxin, ADH)

Mast Cells

release chemical mediators such as histamine that modulate allergic reactions

ACTH, cortisol

released by ant pit acts on the adrenal cortex to promotesynthesis and secretion of cortisol, a steroid hormone produced from cholesterol. However the actually synthesis of this hormone depends on the avaialiability of cholesterol fro transport into the cell and from production of cholesterol by SER not ACTH In conlusion: Patients w/ adrenal insufficiency caused by defective SER proteins can exhibit a limited response to ACTH administration In general ACTH acts to increase the production of cortisol from cholesterol. Cholesterol is synthesized in the RER

sebaceous glands produce

sebum

proteins that are embedded in the plasma membrane traveled through the _____ to arrive there

secretory pathway

During complementary DNA (cDNA) synthesis, reverse transcriptase uses messenger RNA (mRNA) as a template to synthesize a new single-stranded DNA molecule. Because mRNA has the same sequence as the sense strand of genomic DNA (using uracil instead of thymine), cDNA will have the same sequence as the antisense strand. Accordingly, cDNA hybridizes with single-stranded DNA that has the same sequence as the _____ strand of genomic DNA.

sense

mictroubules found in

sperm

trNA charging

tRNA charging refers to the covalent bonding (attachment) of an amino acid to the 3′-OH end of the tRNA molecule.

somatic nervous system

the division of the peripheral nervous system that controls the body's skeletal muscles VOLUNTARY

Flagella

whiplike tails found in one-celled organisms to aid in movement

Functions of Gastrointestinal Tract

1. Food Breakdown in Mouth --> Travels down the esophagus to the stomach where chyme (semifluid mixture of partially digested food) is formed. 2. Chyme leaves Stomach. Chyme enters the intestines. 3. Small Intestine: Intestinal & Pancreatic enzymes breakdown macromolecules, which are absorbed via diffusion through absorptive cell membranes or through intestinal transporters. 4. Large Intestine : Additional Water Absorption, Microbial communities (gut flora) synthesize vitamins and metabolize remaining carbohydrates.

The hypothalmic-pituitary adrenal pathway (HPA) controls the secretion of glucocorticoids form the adrenal cortex as follows:

1. Hypothalamus secretes CRH 2. CRCH acts on anterior pituitary which causes the release of ACTH 3. ACTH stimulates the Adrenal Cortex to synthesize and release cortisol 4. cortisol targets tissues. Also cortisol functions as negative feedback signal by inhibiting the secretion of CRH and ACTH

Microtubules Kinesin and Dynein

A eukaryotic cell's cytoskeleton is an intracellular scaffolding (network) of fibers interspersed throughout the cytoplasm. The cytoskeleton is composed of three types of fibers: Microfilaments, intermediate filaments, and microtubules. Together, these fibers function to organize cellular components, support cellular motility (eg, cell movement, intracellular transport), and give the cell its shape. Kinesin: Moves intracellular cargo along microtubules in anterograde axonal transport (ie, away from the nucleus and toward distal sites). Dynein: Participates in retrograde axonal transport of intracellular cargo (ie, from distal sites toward the nucleus)

When acetylcholine (ACH) is released by the motor neuron at the nueromuscular junction the following occurs:

ACh binds and opens ligand-gated ion channels in the sarcolemma (the plasma membrane of the muscle cell) Na+ flows down its electrochemical gradient and into the cell through the channel, resulting in depolarization of the sarcolemma and generation of an action potential that propagates along the muscle fiber in all directions. At certain locations along the muscle fiber, the sarcolemma burrows deep into the cells, forming a channel known as the transverse (T) tubule, which brings depolarizing current close to the sarcoplasmic reticulum (SR) **The SR is a specialized smooth endoplasmic reticulum responsible for regulating cytosolic Ca2+ levels within the muscle cell. Action potential propagation through the T tubule ultimately leads to the opening of Ca2+ channels in the SR membrane. Because Ca2+ is more highly concentrated inside the SR than in the cytosol, the opening of these channels results in Ca2+ flowing down its concentration gradient and into the cytosol. Cytosolic Ca2+ ions then bind to troponin, which allows the actin and myosin filaments of the sarcomere to slide across one another. The sliding of the filaments results in shortening of the sarcomere and overall muscle contraction The Ca2+ channels in the SR membrane close when the depolarizing stimulus ceases. Active transport Ca2+ pumps sequester the Ca2+ back into the SR, which allows the muscle to return to its relaxed state as cytosolic Ca2+ concentration falls

Antibodies

Antibodies are Y-shaped proteins that bind antigens (ie, foreign substances), allowing for better recognition and destruction of antigens by immune cells. Antibodies contain variable regions that bind specific antigen regions called epitopes. In addition, antibodies bind only one type of antigen, and the antigen bound depends on the antibody's variable region structure. Accordingly, antibodies can be used to identify antigens in molecular experiments.

Freely movable joints, also known as synovial joints, consist of several structures that interact with bone and skeletal muscle:

Articular (hyaline) cartilage surrounds the ends of bones within the joint, providing a smooth surface that absorbs compressive forces and reduces friction between bones as they interact. The joint cavity, located between articulating bones, contains specialized fluid (ie, synovial fluid) that lubricates joint surfaces and protects articular cartilage from excessive friction and damage. Fat pads are adipose tissue structures present in some synovial joints (eg, knee and hip joints) that provide additional cushion between bones within the joint. Ligaments and tendons are rope-like, dense connective tissue structures. Ligaments attach bones to other bones whereas tendons generally attach bones to surrounding muscles

Pulmonary Gas Exchange

As blood flows through systemic capillaries, O2 diffuses into tissues and CO2 diffuses from tissues into blood. Veins transport deoxygenated blood containing CO2 back to the heart. From the heart, deoxygenated blood is pumped to the lungs, where pulmonary capillaries facilitate alveolar gas exchange. Here, O2 diffuses into pulmonary capillaries while CO2 diffuses out and is exhaled. Most of the CO2 entering the blood is transferred into red blood cells (RBCs) and combines with water to form carbonic acid (H2CO3), an unstable compound that rapidly dissociates to form bicarbonate (HCO3−) and hydrogen (H+) ions. This reaction, known as the bicarbonate buffer system, is in equilibrium and helps maintain blood pH: CO2+H2O⇋H2CO3⇋HCO3-+H+ Generally, free H+ ions generated from this reaction bind hemoglobin and other circulating proteins, preventing blood pH from decreasing below the optimal level. In addition, HCO3− ions can bind H+ ions to reform H2CO3, removing additional free H+ ions.

Specialized valves facilitate unidirectional blood flow through the heart

Atrioventricular valves allow blood to flow from the atria to the ventricles and similunar valves allow blood to flow from the ventricles to the arteries.

Autosomal Trait Inhertiance

Autosomal traits arise due to the expression of alleles present on an organism's autosomes. These alleles are passed to offspring through inheritance of the parental autosomes. Because males and females all have the same number of autosomes, autosomal traits are generally expressed in the same proportions in males as in females

Vasoconstriction and Vasodilation

Blood vessels are tubular channels that transport blood throughout the body. Many vessels are surrounded by smooth muscle, which contracts to facilitate narrowing or relaxes to promote widening of the blood vessels in response to neural and hormonal inputs.

Diastole

During the diastole phase, the heart relaxes and fills with blood returning to the heart via the veins. Because blood is not pumped from the heart during diastole, the volume of blood flowing through the arteries is lower, decreasing pressure on the arterial walls. Therefore, arterial blood pressure is lowest during diastole and is measured as the diastolic blood pressure. During the systole phase, the heart contracts and blood is forced from the heart into the arteries. This increased volume of blood flowing through the arteries on contraction of the heart exerts increased pressure (ie, hydrostatic pressure) on the arterial walls. Accordingly, arterial blood pressure is highest during systole and is measured as the systolic blood pressure. Systole/ Diastole

Countercurrent Multiplication in the Loop of Henle

Filtrate flows through the descending limb of the loop, which is highly permeable to water but impermeable to NaCl. Water will move from areas of low solute concentration to areas of high solute concentration. Accordingly, because salt concentration in the medulla is high, water is passively reabsorbed (via osmosis) from the filtrate flowing through the descending limb into the salty medulla, where it is taken up by blood vessels. Filtrate then flows into the ascending limb, which is highly permeable to NaCl but impermeable to water. Initially, NaCl is passively reabsorbed into the medulla as filtrate moves up the ascending limb. However, as the ascending limb nears the cortex, NaCl is actively transported from the filtrate into the medulla, preserving the medulla's high salt concentration. Because water follows NaCl, the saltiness of the medulla promotes continued water reabsorption from the descending loop of Henle and the collecting duct.

Menstruation Levels

First Half FSH is released from the Ant Pit ---> development of the follicles, gradually rises and falls right before ovulation Estrogen is released by the development of the follicles and gradually rises and falls right before ovulation LH does not really change much, until it spikes right before ovulation Very low level of progesterone , does not really have a role Second Half - Progesterone and Estrogen are increasing produced by the corupus luteum (help to thicken and matain endometrium). - No fertilization, causes corupus luteum to degenerate ---> progesterone and estrogen levels will drop : Menstruation occurs - Progesterone and Estrogen are high, thus FSH and LH will be low. - However at the very end of the phase, the negative feed back is removed and FSH starts to be secreted, cycle restarts.

A single layer of endothelial cells comprises the inner wall of all blood vessels, forming a barrier that regulates the entry and exit of materials into and out of the bloodstream. In addition, endothelial cells secrete chemical signals that generally prevent blood coagulation (ie, clotting). However, injury to a blood vessel that results in bleeding indicates damage to the endothelium and triggers the following cascade of event

Formation of the platelet plug. Endothelial damage exposes connective tissue (ie, collagen fibers) normally present outside the blood vessel. Circulating cell fragments called platelets (derived from the bone marrow) readily bind these collagen fibers, aggregating to form a platelet plug (clot) that prevents blood flow out of the vessel. In addition, bound platelets and endothelial cells near the site of damage continue to release signals that enhance platelet aggregation. Strengthening of the clot. Clotting factors (mainly synthesized in the liver) are specialized proteins that become activated in response to platelet aggregation and signaling factors outside the vessel. Activated clotting factors induce processes that lead to the formation of the enzyme thrombin. Thrombin induces protein strands (ie, fibrin) to form an adhesive mesh-like structure over the platelet plug, reinforcing the clot.

Menstrual Cycle

Gonadotrophin Releasing Hormone is released from the Hypothalmus ---> FSH and LH are released from the anterior pituitary Two Phases 1. Follicular Phase: stimulates development of follicles 2. Luteal Phase : ovulation - follicle that releases the ovum, colapses and becomes the corpus luteum which secretes high level of progesterone. Oestrogen: Steroid Sex Hormone that promote female characteristics, development of endometrium, thin cervical mucus. - negative feedback on Ant pit and Hypothalmus (thus increase in estrogen means decreases in FSH and LH) Progesterone: Steroid Sex Hormone, Corpus Luteum secretes progesterone after ovulation. If pregnancy occurs than placenta will take over the secretion of progesterone, thickening and maintain endometrium If egg is fertilized, the embroyo secretes human gonadrophin HCG and that keeps the corpus luteum alive. if egg is not fertilized, the corpus luteum will degenerate and stops producing progesterone and estrogen. This removes the negative feedback to the hypothalmus and pituitary. Causing the levels of FSH and LH to rise again, thus cycle can start agin. Endometrium will also breakdown and shed - menstruation

Heterochromatin

Heterochromatin consists of DNA that is tightly coiled around histone proteins, bound by an ionic interaction between the negatively charged phosphates on the DNA backbone and positively charged lysine residues in the histone. DNA in heterochromatin is not readily accessible to RNA polymerase and so cannot be readily transcribed.

Chromatic Strucutre (heterochromatin or euchromatin) affects gene expresison by regulating transcription.

Heterochromatin is tightly wound DNA characterized by low levels of histone acetylation and high levels of DNA methylation. Genes in these regions are considered silenced because the DNA is so tightly packed that it is inaccessible to the transcription machinery. In contrast, euchromatin is marked by high levels of histone acetylation and low levels of DNA methylation. This makes euchromatin looser and the DNA more accessible to the transcription machinery, allowing gene expression.

substances in plasma

Hormones Salts Nutrients Wastes

Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (SDS-PAGE) is an electrophoresis technique used to separate proteins based on molecular weight (size). SDS is a strong anionic detergent that denatures and confers a net negative charge on the protein, eliminating its shape and charge as separation factors. When this technique is used, larger proteins migrate a shorter distance toward the positive electrode than smaller proteins.

However, SDS disrupts only noncovalent bonds. Therefore, a protein containing multiple covalently bound polypeptide subunits presents as a single band in SDS-PAGE electrophoresis. When SDS-PAGE is performed under reducing conditions, a reducing agent (eg, 2-mercaptoethanol) is added to disrupt disulfide bridges, allowing each subunit to separate as individual polypeptides.

Components of Adaptive Immune System

Humural: B lymphocytes What are the two types of B lymphocytes 1. Plasma Cells --- secrete antibodies that mark foreign antigens for destruction by the immune system 2. Memory B cells ---> more rapidly recognize and respond to foreign antigens in future infections. CELL MEDIATED: T Lymphocytes 1. Helper T Cells: secrete cytokines that enhance the activity of other immune cells 2. Cytotoxic T cells : secrete cytotoxins that induce apoptosis in infected cell s 3. Regulatory T cells: secrete cytokines that inhibit the activity of other immune cells: 4. Memory T cells: more rapidly recognize and respond to foreign antigens in future infections

genetic leakage (gene flow)

Hybrid offspring are produced when members of two different species mate. If these hybrid offspring mate with either parental species that produced the hybrid, genetic leakage (ie, the transfer of genes between different species) may occur.

Immune Cell Assisted By Helper T cell

In cell-mediated immunity, T lymphocytes (cells) recognize and mount immune responses against foreign antigens displayed by other cells on specialized surface proteins called major histocompatibility complex (MHC) proteins. MHC proteins on any given cell display fragments of any proteins present within that cell. Accordingly, cells containing foreign pathogens, such as certain immune cells or infected cells, will generally display foreign protein fragments (antigens) on their MHC proteins. Helper T cells are T cells that recognize foreign antigens displayed by MHC proteins of other immune cells, such as: B lymphocytes, cells that bind and engulf a foreign antigen. The antigen is broken down into fragments within the B lymphocyte, and these fragments are transported to be displayed on MHC proteins present on the cell membrane. A helper T cell binds the foreign antigen presented by the B lymphocyte and releases signaling molecules (cytokines) that induce division of the B lymphocyte into many identical cells, some of which differentiate to secrete antibodies against the invading pathogen. Macrophages and dendritic cells, which engulf foreign antigens (via phagocytosis) and present these antigen fragments on the MHC proteins found on their cell membrane. Upon binding these antigens, helper T cells release cytokines that enhance other immune responses, including the phagocytotic activity of macrophages and the activation and proliferation of cytotoxic T cells, immune cells that release toxins to induce apoptosis in infected cells.

lysogenic life cycle

In contrast, bacteriophages that have a lysogenic life cycle also attach to the bacterium but integrate their genome into the host DNA; these viruses are called prophages. This viral genome integration enables the host cell to survive and divide normally. While the host cell divides, the integrated viral DNA is replicated with the host DNA, and associated viral repressor proteins prevent the viral genome from being transcribed (latency). Induction can occur in response to environmental factors (eg, chemicals, radiation), causing the viral genome to excise itself from the host chromosome and enter the lytic life cycle.

Hemoglobin is an oxygen-binding protein found within red blood cells (RBCs). Oxygen diffuses into the bloodstream via gas exchange in the lungs, binds hemoglobin, and is transported through the circulatory system to tissues throughout the body. Deleterious mutations affecting hemoglobin genes may negatively impact hemoglobin function, impairing oxygen transport.

In this scenario, a patient is homozygous for a deleterious mutation in a gene coding for a hemoglobin subunit. Expression of this mutant gene would likely produce a portion of the hemoglobin protein with impaired function. Because RBCs are produced from stem cells in the bone marrow, the most effective treatment for this patient would be gene therapy to introduce and activate a functional hemoglobin gene in bone marrow stem cells. This would likely lead to the production of RBCs that contain hemoglobin with normal oxygen-binding abilities.

The glomerular filtration rate (GFR) is the rate (amount per unit time) at which fluid is filtered out of the glomerular capillaries (collectively known as the glomerulus) and into the Bowman capsule. GFR is proportional to the hydrostatic (blood) pressure within the glomerulus. As such, GFR can be expected to decrease if the afferent arterioles constrict (ie, because less blood enters the glomerulus) or the efferent arterioles dilate (ie, because more blood exits the glomerulus).

In this scenario, a patient receiving blood transfusions exhibits liver damage caused by iron buildup. The passage states that iron-bound transferrin (holoTf) could be filtered through the kidney. Therefore, if GFR decreased in the kidney, the likely result would be increased retention of iron-bound transferrin (holoTf) in the blood, which would contribute to iron buildup in the liver. Decreased hydrostatic pressure within the glomerulus can lead to decreased GFR (and consequently decreased holoTf filtration rates) because the flow rate of filtered fluid through the kidney will decrease.

Neutrophils

Kill and phagocytize bacterial cells

During the follicular phase of the cycle (oocyte plus supporting granulosa) clls) matures until it bulges at the outer wall of the ovary

Maturation and Growth of the Follicle is driven by the release of follicle stimulating hormone (FSH) from the anterior pituitary. A subsequent release of luteinizing hormone (LH) stimulates follicle rupture and the release of the secondary oocyte near the opening of the fallopian tube (ovulation)

Mitosis is essential for embryonic growth and production of the organism's somatic cells. Failure of sister chromatids to segregate properly (eg, due to chromosomal nondisjunction) during embryonic mitosis generates cells containing missing or extra genetic information. Accordingly, the ability of these cells to divide and differentiate into functional somatic cells in the embryo would be impaired. This would inhibit zygote development and likely cause early embryon

Meiosis is the process by which diploid organisms produce haploid gametes. Although the parents needed to perform proper meiosis to produce the offspring embryos, errors by the offspring embryos would not be apparent until the offspring attempt to sexually reproduce. The question states that the embryos died during development, before they had a chance to attempt sexual reproduction.

Sliding Filament Model of Muscle Contraction

Muscle contraction is dependent on the interaction between the myosin (thick) and actin (thin) protein filaments in the sarcomere, the basic contractile unit of muscle tissue. To generate muscle contraction, the sarcomere functions as follows: When the muscle fiber is at rest, the myosin head is in its high-energy conformation (upright and bound to ADP and Pi), and the actin filaments are bound by the regulatory proteins tropomyosin and troponin. Tropomyosin is an elongated protein that wraps around the actin filament to block myosin-binding sites on this thin filament. Troponin is a small protein complex associated with tropomyosin. Following a depolarizing stimulus by a motor neuron, Ca2+ ions are released from the sarcoplasmic reticulum into the cytosol. The abundant cytosolic Ca2+ ions bind troponin, causing a conformational change that ultimately pulls on tropomyosin and exposes the myosin binding sites on the actin filaments (Choice D). When the active sites are exposed, the myosin head is able to bind strongly to the actin filament, forming a cross-bridge. The dissociation of Pi initiates the power stroke, which is the actual pivot of the actin-bound myosin head that drags the actin filament toward the center of the sarcomere. This directly results in shortening of the sarcomere. The release of ADP from the myosin head occurs at the end of the power stroke. The myosin head is now in its low-energy conformation. A new ATP molecule binds the myosin head and the cross-bridge disassembles Hydrolysis of the ATP molecule allows the myosin head to shift back into its upright, high-energy conformation in preparation for a new cycle of contraction The cycle of cross-bridge formation and disassembly continues until motor neuron signaling ceases, and Ca2+ is sequestered back into the sarcoplasmic reticulum. P stands for Power Stroke

Excess post-exercise oxygen consumption (EPOC), or oxygen debt, represents the amount of oxygen necessary to bring a muscle back to its resting state. EPOC is the difference between the amount of oxygen required for the physical activity and the total amount of oxygen used.

Muscles require ATP to contract. Aerobic respiration uses oxygen to generate more molecules of ATP per metabolized glucose molecule than anaerobic glycolysis. Consequently, aerobic respiration is the primary source of ATP in muscle fibers during vigorous, long-term exercise. However, when oxygen delivery from the blood is insufficient (eg, during rapid, high-intensity exercise) or the demand for contraction exceeds the speed at which aerobic respiration can generate ATP, muscle fibers compensate by: utilizing ATP that is stored in the muscle fiber. breaking down creatine phosphate, a high-energy molecule stored by muscle cells during periods of rest, to generate ATP. generating ATP via anaerobic glycolysis, which yields 2 pyruvate molecules and 2 net ATP molecules per glucose molecule. In the absence of oxygen, the 2 pyruvate molecules are converted to lactic acid. continuing aerobic respiration using oxygen that is bound to myoglobin, a red-pigmented oxygen storage molecule.

Natural Killer Cells vs T cells

Natural Killer Cells are cellular components of the innate immune system and release toxins to destroy body cells (i.e neoplastic and virus infected cells that have reduced expression of major histocompatibility complex molecules). T cells are cellular components of the adaptive immune system.

Release of Cytotoxins By Cytotoxic T Cells and Natural Killer Cells

Natural killer and cytotoxic T cells, not B lymphocytes, respond to antigens by releasing toxins that induce apoptosis (cell death) in nearby infected cell

Do T-lymphocytes present antigen fragments on cell membranes?

No! Phagocytic cells (eg, macrophages, dendritic cells), not T-lymphocytes, present antigen fragments on cell membranes and engulf foreign substances and cellular debris.

Is collecting multiple samples from a single individual a valid way to increase sample size

No!! The samples need to be indepent of each other and should be selected at random.

Does cDNA have introns?

Nope. Complementary DNA (cDNA) is derived from mature mRNA through reverse transcription. Because the mature mRNA has already been spliced (ie, introns were removed), the cDNA will not contain any introns. The cDNA can be cloned into expression vectors such as plasmids, which can be introduced into embryonic cells and integrated into the genome. These cloned genes can then be expressed in the organism. However, because the cloned gene does not contain any introns, its expression will not include splicing.

The adrenal cortex secretes the hormones cortisol and aldosterone, and the adrenal medulla secretes the hormones epinephrine and norepinephrine

Norepinephrine and epinephrine achieve this effect by promoting the following changes in blood vessel diameter that lead to altered blood pressure: Vasoconstriction (narrowing) of blood vessels supplying the intestines, kidney, and other abdominal organs decreases blood flow to these organs and conserves oxygen/nutrients for other tissues. Vasodilation (widening) of blood vessels leading to the heart and skeletal muscles increases oxygen/nutrient delivery to these organs.

Oogenesis

Oogonium (Diploid) ----> Primary Oocyte (diploid) via Mitosis. Primary Oocyte is arrested in Prophase 1 until puberty Primary Oocyte (diploid) ---> Secondary Oocyte via Meiosis I Secondary Oocyte is arrested in Metaphase II until fertilization. Once Fertilization occurs it goes from Secondary Oocyte (haploid) to Ovum (haploid) via Meiosis II Notes - all of a womans devleoping eggs (oocytes) are produced during fetal development - at birth, thier maturation is arrested in prophase 1, these arrested eggs are known as primary oocytes - at puberty, the menstrual cycle begins and each moth a single primary ooocyte develops into a secondary oocyte by continuing meiosis up to metaphase II

What is an obligate aerobe? What is an obligate anaerobe? What is a facultative anaerobe? What is an aerotolerant anaerobe?

Oxygen dependence is determined by a bacterium's ability to use fermentation, anaerobic respiration, aerobic respiration, or some combination of these to generate ATP from various nutrients.

The primary function of macrophages, which can either travel the body or remain fixed in a specific tissue, is to degrade pathogens and dead body cells. The degradative function of macrophages is performed via

PHAGOCYTOSIS the process of engulfing solid particles (microbial pathoges) designated for destruction into phagocytic vesicles called phagocytes). Within the cell, phagosomes typically fuse with lysosomes to form phagolysosomes which enable the degradation of the engulfed particles using specialized enzymes that work at low pH

Transcription Factors are

PROTEINS and they alter gene expression via binding to DNA upstream from promoters NOTE: Transcription factors can be activators or they can be repressors of a specific gene

To regulate calcium homeostasis, parathyroid hormone (PTH) and calcitonin act antagonistically to each other.

PTH is secreted in response to a low blood calcium level and stimulates bone resorption by osteoclasts, causing an increase in blood calcium. In contrast, calcitonin is secreted in response to a high blood calcium level and decreases osteoclast activity, ultimately decreasing blood calcium

Parallel vs Divergent vs Convergent Evolution

Parallel evolution occurs when two more closely related species (ie, descended from a recent common ancestor) continue to evolve the same characteristics to adapt to similar environments. Because the flying squirrel and Draco lizard do notshare a recent common ancestor, they are not displaying parallel Divergent evolution occurs when two species descended from a recent common ancestor inhabit contrastingenvironments and evolve distinct characteristics that allow them to better adapt to their differing environmental pressures. The flying squirrel and Draco lizard share similar (not distinct) characteristics; therefore, this is not an example of divergent evolution. Convergent evolution leads to similar characteristics in distantly related species that are exposed to similar environmental pressures.

Mitosis includes what phases?

Prophase: DNA condenses to form chromatids. Each pair of sister (identical) chromatids are joined by a region called the centromere to form chromosomes. The nuclear envelope breaks down and centrosomes (microtubule-organizing structures) migrate to opposite poles within the cell. The mitotic spindle is formed as microtubules grow from these centrosomes. Metaphase: Chromosomes attach to spindle fiber microtubules at their kinetochores and align at the metaphase plate, a central plane within the cell. Anaphase: Sister chromatids are pulled apart by the spindle fibers and move toward opposite poles of the cell. This forms two sets of chromosomes within the cell (one set at each cellular pole). Telophase: The nuclear envelope is reformed around each set of chromosomes. Chromosomes decondense and the parental cell undergoes cytokinesis (cytoplasmic division) to produce two identical daughter cells.

Northern blotting is an assay used to detect and measure the concentration of specific RNA molecules within a cell or tissue sample. A typical procedure is as follows:

RNA is isolated from the tissue and denatured. The RNA is separated by size via gel electrophoresis. The RNA samples are transferred from the gel to a blotting membrane and immobilized. The membrane is incubated with a labeled RNA or single-stranded DNA probe complementary to the RNA sequence of interest. If the sequence of interest is present, the probe binds to it (ie, hybridizes) and the label (eg, radioactive atom, fluorescent dye) allows visual detection of the probe. The sample is washed to remove unbound probes. Researchers determine if a visual signal is present. A visual signal indicates that hybridization occurred, meaning the RNA sample contains the RNA sequence of interest. The lack of a visual signal corresponds to an absence of the target RNA sequence.

The two components of ER

ROUGH ER and SER

Passive Transport

Simple diffusion and facilitated diffusion are both forms of passive transport, in which no energy input is required and molecules diffuse down their concentration gradient. In simple diffusion, molecules that are small or lipid-soluble travel across the cell membrane directly, without help from protein channels. In facilitated diffusion, molecules that cannot normally cross the membrane on their own due to charge or size are allowed to pass through protein channels or gates that do not require energy input to operate.

Enteropeptidase

Site of Secretion: Intestinal gland Site of Function: Small Intestin Function: Converts trypsinogen into its secrted from trypsin

Slow twitch (type 1) oxidative fibers

Slow-twitch (type 1) oxidative fibers contract at a slow rate due to the lesser frequency at which the myosin heads hydrolyze ATP during each contractile cycle. These fibers produce ATP via aerobic respiration. Therefore, they contain many mitochondria that use oxygen in the electron transport chain to produce large amounts of ATP (energy), making these fibers more fatigue resistant. Type 1 fibers receive oxygen from their extensive capillary networks and high concentrations of myoglobin.

What can be used to analyze gene count

Southern blot and Dna sequencing

Activaction of B Lumphocytes by Helpter T Cells

Specifically, humoral immunity is driven by B lymphocytes that secrete antibodies, specialized proteins that recognize specific foreign antigens by binding to epitopes (eg, regions on viral or bacterial antigens to which antibodies bind). These antibodies circulate throughout the blood and lymph, binding foreign antigens and marking them for destruction by other immune cells Mature B lymphocytes are inactive until their receptors bind a specific foreign antigen. On activation by antigen binding, B lymphocytes can endocytose (engulf) the antigen, breaking it down into smaller fragments. Within the B lymphocyte, specialized antigen-binding molecules called major histocompatibility class II (MHC II) proteins bind the antigen fragments. Although all nucleated cells can display antigens on MHC I proteins, typically specialized ("professional") antigen-presenting cells display antigens on MHC II proteins.

In males, the testes contain specialized, coiled structures called seminiferous tubules, which are the locations of spermatogenesis (ie, sperm production). Within the seminiferous tubules, spermatogenesis proceeds as follows:

Spermatogonia undergo mitotic division, forming two daughter cells. One of these daughter cells remains a spermatogonium while the other becomes a primary spermatocyte and begins meiosis. Meiosis I results in two secondary spermatocytes. Completion of meiosis II by the secondary spermatocytes yields four spermatids. The spermatids undergo several changes (eg, cytoplasm loss, acrosome formation, tail development), ultimately developing into spermatozoa. The spermatozoa migrate to the epididymis where they continue maturation and acquire motility.

Blood is the only fluid connective tissue in the body and is composed of living blood cells and nonliving plasma. The cellular components of blood originate from the bone marrow: Erythrocytes, which have a role in oxygen transport; leukocytes, which contribute to immune defense; and platelets, which are crucial in blood clotting. Plasma is the liquid portion of blood and is approximately 90% water, with the remaining 10% composed of other substances (eg, proteins, respiratory gases)

The 19 missing amino acids likely make up a signal sequence, a short amino acid sequence present at the N terminus of immature proteins. The signal sequence directs proteins to the rough endoplasmic reticulum for entry into the secretory pathway before being cleaved from the polypeptide. In this case, transferrin is trafficked through the entire pathway for secretion into extracellular space. Once secreted from liver cells, the shortened transferrin enters circulation and is incorporated into the plasma

anterior pituitary gland

The anterior lobe is made up of glandular tissue containing different cell types that synthesize and secrete follicle-stimulating hormone (FSH), luteinizing hormone (LH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), growth hormone (GH), β-endorphins, and prolactin. The synthesis and secretion of hormones from the anterior pituitary is controlled primarily by neurohormones released from hypothalamic neurons. These regulatory neurohormones are secreted into the hypophyseal portal system, a venous network of small blood vessels that enables small quantities of hormones secreted from the hypothalamus to directly reach the anterior pituitary without being diluted in the circulation.

Secretary protein

The endoplasmic reticulum is a cytosolic organelle composed of a network of membranous sacs and tubules. It is divided into the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER) The RER has ribosomes located along its surface that translate proteins destined for the secretory pathway. Translated proteins may undergo certain modifications (eg, glycosylation) in the RER. Next, proteins in the RER are transported to the Golgi apparatus, where additional modifications may occur followed by the packaging of the proteins into vesicles. Proteins transported via vesicle from the Golgi apparatus may be secreted from the cell, added to the cell membrane, or used by certain organelles (eg, lysosomes).

Endosomal pathway

The endosomal pathway begins at endocytosis where, following internalization of extracellular materials into vesicles, the vesicles containing these materials mature to early endosomes, late endosomes, and finally, lysosomes. The lysosome is a membrane-enclosed organelle that serves as the "digestive system" of the cell; it contains an acidic environment (pH ≈ 4.5) and various hydrolytic enzymes that facilitate the degradation of various biomolecules (eg, proteins, carbohydrates, nucleic acids, lipids).

log scale

The equal intervals are powers of 10: 101 to 10 squared is the same distance as between 10 squared to 10 cubed. curved on a graph not linear

Repair of Double Stranded DNA Breaks (DSB)

The exterior backbone of DNA consists of deoxyribose (5-carbon/pentose) sugars and phosphate groups that alternate with one another. The 3′-hydroxy group of the deoxyribose from a deoxyribonucleotide monomer binds via phosphodiester linkage to the 5′-phosphate group of another deoxyribonucleotide monomer DNA contains four nitrogenous bases: the purines adenine (A) and guanine (G), and the pyrimidines cytosine (C) and thymine (T). These bases are held together in this ladder formation via hydrogen bond

Female Reproductive Anatomy

The female reproductive organs are the sex-specific structures that enable the conception and delivery of an infant. Impaired function within any of the female reproductive organs may result in infertility, the inability to become pregnant. The following are important female reproductive structures that, if affected by endometrial implants, may lead to infertility: Vagina: The sexual organ through which sperm enters the uterus. Endometrial implants within the vagina may impair the passage of sperm and decrease the likelihood that an ovulated oocyte will be fertilized (Choice B). Ovaries: The female gonads that produce gametes (oocytes) and secrete female sex hormones. Endometrial implants attached to the ovary may cause infertility by impairing follicular maturation or ovulation, the release of an oocyte (egg cell) (Choice D). Fallopian tubes: Duct structures lined with motile cilia that transfer the ovulated oocyte from the abdominal cavity toward the uterus; they are also the primary site of fertilization. Endometrial implants that block or impair the function of the fallopian tubes would prevent a fertilized oocyte from reaching the uterus for implantation (Choice C). Cervix: The barrier separating the vagina and uterus. Endometrial implants that block the cervical canal may impair the passage of sperm and decrease the likelihood of fertilization.

The glomerular capillaries contain large pores through which blood passes as it is filtered based on particular size. These capillaries are lined by a basement membrane that allows for the passage of water, many solutes and very small proteins into the filtrate.

The filtrate is collected by the Bowmans Capsule which surrounds the glomerulus, and is delivered to the proximal convoluted tubule (PCT), the next section of the nephron.

Why is the genetic code degenerate

The genetic code explains how four kinds of DNA nucleotides (A, T, G, and C) can specify the 20 amino acids necessary for protein synthesis. Sequences of three nucleotides in DNA or RNA are known as codons. Genes contain codons that are sequentially transcribed into mRNA codons that code for amino acids during translation. Mathematically, there can only be 64 (or 43) possible arrangements of the four DNA nucleotides into codons. However, the genetic code is often considered degenerate or redundant because although there are 64 codons, only 20 amino acids are used for protein synthesis. In translation, each mRNA codon (except the stop codons) base pairs with the complementary anticodon of a tRNA molecule that is "charged" with a corresponding amino acid. The anticodon of a single tRNA molecule can base pair with different mRNA codons that code for the same amino acid. This redundancy of the genetic code can be explained in part by the wobble hypothesis. This hypothesis states that the first two nucleotides on the mRNA codon require traditional (Watson-Crick) base pairing with their complementary nucleotides on the tRNA anticodon, but the third nucleotide on the codon may undergo less stringent ("wobble") base pairing in a non-Watson-Crick manner. Codon degeneracy is therefore explained by nontraditional basepairing at the third position of the codon and anticodon.

The given scenario describes the genetic transmission of an X-linked recessive disorder characterized by muscle degeneration. The mother is a carrier, meaning she has the disease-causing allele but does not express the disorder, whereas the father does not carry the allele and is unaffected by the disorder. What would the children expresss

The given scenario describes the genetic transmission of an X-linked recessive disorder characterized by muscle degeneration. The mother is a carrier, meaning she has the disease-causing allele but does not express the disorder, whereas the father does not carry the allele and is unaffected by the disorder.

The hypodermis

The hypodermis is composed of adipose tissue and functions in insulation and shock absorption

NMJ

The interface between somatic motor neuron and skeletal muscle fiber is a specialized synapse known as the neuromuscular junction. The NMJ converts motor neuron action potentials into muscle fiber action potentials

The sarcoplasmic reticulum (SR) is a specialized endoplasmic reticulum found in skeletal muscle fibers

The main role of the SR is to store calcium ions (Ca2+) that, if constantly present in the cytosol, would lead to inappropriate activation of numerous processes (eg, proteolysis by Ca2+-activated proteases). In striated muscle fibers (ie, those of cardiac and skeletal muscles), the SR is the source of most Ca2+ released into the cytosol in response to stimuli (eg, depolarization). The storage of Ca2+ within the SR generates a large Ca2+ concentration gradient across the wall of the SR. he sarcoplasmic reticulum (SR) stores the Ca2+ necessary for skeletal muscle contraction to occur. A specific Ca2+channel permits diffusion of Ca2+ out of the SR, and a specific ATPase pumps Ca2+ from the cytosol back into the SR.

Prteasome

The proteasome is a protein complex found in the cytosol that typically degrades ubiquitinated proteins. For viral particles to follow this pathway, they would first have to escape the endosome and enter the cytosol, and particles that fail to escape will never interact with the proteasome.

n this scenario, a patient exhibits reduced pulmonary blood flow and excess fluid accumulation in the abdomen and legs. These symptoms are best explained by reduced blood flow through the heart valve separating the right atrium and right ventricle (ie, right AV valve). This condition would decrease the volume of blood loaded into the right ventricle prior to contraction, reducingblood flow from the right ventricle into the pulmonary arteries.

The reduced volume of blood flowing into the right ventricle and through the pulmonary circuit would in turn cause a backup of blood in the right atrium and systemic vessels. Accordingly, blood volume and hydrostatic pressure in systemic veins would increase, causing excess fluid leakage from systemic vessels into the surrounding interstitial fluid and subsequent fluid accumulation (edema) around tissues.

Spleen Function

The spleen is the largest lymphoid organ in the body. It is situated in the upper left portion of the abdominal cavity, just above the stomach and below the diaphragm. The spleen performs the following functions: Filters senescent (worn-out, aged) or damaged red blood cells (RBCs) from the blood. In addition to destroying foreign material, macrophages in the spleen trap and phagocytize aged RBCs and recycle their parts . (Note: The liver is also involved in the removal and reuse of aged RBCs.) Serves as a reservoir for blood. This blood can be released in the event of a sudden drop in blood volume Participates in immune function by housing macrophages that phagocytize and destroy foreign substances and by serving as a site of B-cell activation (Choice A). Each B cell expresses a unique antibody that recognizes and binds a specific pathogen, preventing it from entering host cells and marking it for phagocytosis. An activated B cell (ie, one that has come in contact with its corresponding pathogen) rapidly proliferates to produce memory and effector B cells. Effector B cells (ie, plasma cells) produce antibodies against the current infection, and memory B cells are responsible for long-term defense against a similar infection in the future. Individuals who do not have a functional spleen cannot mount B-cell responses as efficiently, and their lifetime risk of infection is increased

An increase in the volume of air reaching the alveoli and exchanging with the blood means what?

There is more c02 in the blood to enter the alveoli and be exhaled. This will increase blood pH

Skin oils have a bacterial function which is:

They are part of the body's innate immune system and kill harmful bacteria on the skin's surface. In addition, these oils slow the amount of water lost from the skin via evaporation. If skin oils decrease, more water is able to evaporate through the skin surface. Therefore, because frequent hand-washing causes more water to be lost through the skin, the skin can become more irritated.

In an isolated population of 10,000 rabbits, 900 are homozygous for a recessive mutant Sp1 allele. Assuming the population is in Hardy-Weinberg equilibrium, what is the percentage of rabbits in the population that would be heterozygous for the mutant Sp1 allele

To determine 2pq, the following calculations must be performed: Solve for q. Let p represent the frequency of the WT Sp1 allele (S) and q represent the frequency of the recessive mutant allele (s). Here, 900 of 10,000 rabbits are homozygous recessive (ss) for the mutant allele. Given that q2 is equal to the frequency of the homozygous recessive genotype (ss), the following solves for q: q2=0.09 q=0.3 Use p + q = 1 to calculate p: p+q=1 p+0.3=1 p=1-0.3=0.7 calculate the frequency of the heterozygous genotype (Ss) using 2pq: 2pq=20.70.3=0.42

Transcription factors have nuclear localization sequences that facilitate their entry into the cell nucleus, where they regulate the expression of target genes

Transcription factors are proteins that can alter gene expression by binding DNA near gene promoter regions to either increase or decrease the transcription of a target gene. Like all proteins, transcription factors are translated in the cytoplasm and must enter the nucleus (where DNA is stored) to influence gene expression. Transcription factors rely on their nuclear localization sequence to gain entrance to the nucleus. The nuclear localization sequence is composed of amino acids and functions as a nuclear import tag that is recognized and bound by nuclear import proteins, which facilitate the transport of transcription factors into the nucleus.

DNA polymerase is involved in replication NOT transcription

Transcription factors do not affect DNA polymerase binding to DNA

Transfection

Transfection is the process by which genetic material, usually in the form of a plasmid, is introduced into eukaryotic cells. NOTE EUKARYOTIC CELLS

Transposons

Transposons are small fragments of DNA that can move between different regions of the genome. Movement of a DNA sequence, such as a transposon, from one chromosomal arm to another may alter the nucleotide sequence of each chromosome but would not reduce chromosome number in the yeast cell.

Skeletal muscle fibers (cells) can be identified as types 1 (slow oxidative), 2A (fast oxidative-glycolytic), or 2X (fast glycolytic); this classification scheme is based on two features of muscle fibers: ---> Their contractile speed (fast or slow). Contractile speed is determined largely by the catalytic speed of the myosin ATPase and the activity of the associated motor neuron at the neuromuscular junction. ----> Their primary means of producing ATP (oxidative or glycolytic). Oxidative fibers are specialized to use aerobic respiration, whereas glycolytic fibers are specialized to use anaerobic glycolysis.

Type 1 fibers are fatigue resistant, contract slowly, and use aerobic respiration as their primary method of ATP production. Consequently, compared with glycolytic fibers, type 1 fibers are much richer in mitochondria (Number I), the site where many enzymes involved in aerobic respiration reside. Type 1 fibers also have access to a continuous supply of oxygen (the final electron acceptor of aerobic respiration) through an extensive network of capillaries (Number II) that surround the muscle fiber. In addition, type 1 fibers appear red under the microscope due to high concentrations ofmyoglobin, a red-pigmented, oxygen-binding molecule that aids in delivery of oxygen to the muscle cell interior

Western blotting steps

Western blotting is a method that can be used to detect the expression levels of specific proteins in a sample (eg, tissue, cell culture sample). During western blotting, the following steps are taken: Proteins are extracted (eg, from tissue such as a spinal cord segment) Gel electrophoresis is performed on the proteins to separate them by size. Larger proteins will migrate a shorter distance through the gel than smaller proteins. - Note proteins are seperated using SDS page which coats all proteins with negatively charged Proteins are transferred from the gel to a protein-binding membrane (eg, nitrocellulose), where they are immobilized. Protein-rich mixtures are used to block portions of the membrane to which proteins were not transferred. This prevents antibodies (ie, another type of protein) from binding nonspecifically to the membrane in steps 5 and 6. The membrane is incubated with primary antibodies that bind specific proteins. Secondary antibodies, which include fluorescent labels, are applied and bind primary antibodies. Antibodies bound to the proteins are detected via fluorescence, allowing specific protein bands to be visualized. Thicker bands indicate that the protein is more highly expressed.

When GFR decreases what happens to urine output

When GFR decreases, as it does with afferent arteriole stenosis, less filtrate is produced and urine output decreases.

Telomeres explain

When telomerase extends telomeres, it does so by adding the sequence 5′-TTAGGG-3′ to the end of one of the strands on the chromosome multiple times in succession. DNA polymerase then adds the complementary bases to the other strand to generate double-stranded DNA. As a result, telomeres contain highly repetitive DNA, with the repeated sequence being 5′-TTAGGG-3′.

Keratinocytes make Keratin explain

a unique protein protection against injury to the skin waterproofing quality to the skin and helps guard against pathogen entry when the same area of the skin is subjected to repeated frinction, calluses or excessive keratin deposits can form

lac repressor and transcription

absense of lactose (i.e glucose rich media) --- represser binds presence of lactose, lactose binds to repressor to allow for transcription, repressor thus getts off

Unbound ACH may diffuse away from the synapse of be degraded by the enzyme

acetylcholinesterase (AChE), terminating muscle fiber contraction

The three major cytoskletal components aree

actin filaments (i.e microfilaments), intermediate filaments and microtubules

Stmuli that promote the accumulation of newly synthesized proteins are referred to as anabolic, whereas stimuli that inhibit protein synthesis (or stimulate protein degradation) are referred to as catabolic.

anabolic hormones are those associated with the accumulation of newly synthesized proteins, whereas catabolic hormones are those associated with decreased protein accumulation. GH is an anabolic hormone that promotes protein synthesis and growth in multiple tissues.

Extracellular calcium concentrations are so much higher than those in the cytosol of the cell

and entry of calcium in to the cytosol can depolarize (i.e increase the membrane potential) of the cell.

mRNA transcripts are considered expressed genes

and when scientists are interested in specific mRNA transcripts, RT-PCR can be used to analyze cells. Reverse Transcriptase (an enzyme) is used to convert mRNA to double stranded cDNA, which can be amplified through PCR using primers specific to the mRNA of interest. AFterwards, samples can be analyzed using gel electrophoresis for the presence or absense of a specific transcript.

Plasmids carrying antibiotic resistance genes can transmit

antibiotic resistance to recipient cells

Tight Junctions

are cell-cell junctions that PREVENT water and SOLUTES from diffusing between cell and across the epithelial layer. These junctions form a watertight seal that fully encircles the apical end of every cell in the basal epithelial sheet. Barrier and seperate tissue space. FOund in many tissues such as skin, gastrointestinal tract and testis

microtubules are involvewd in cilial formation. However cilia are found

at the edge of the cell, adn the endosomes are moving away from the edge and toward nucleus in the central region of the cell

Peptide hormones typically are hydrophilic, not bound to transport proteins in the blood, and steroid hormones are lipophilic (being derived from cholesterol) and are typically

bound to transport proteins in the blood but can diffuse across cellular membranes

Mitosis

cells divides to create two genetically identical daughter cells. crossing over DOES NOT occur

Eukaryotic genomes consist of linear chromosomes made up of DNA that can be translated and transcribed into proteins. Each chromosome has a condensed region of repetitive noncoding DNA called the_______ a structure that facilitates spindle fiber attachment during mitosis and meiosis. In addition, eukaryotic chromosomal ends consist of repetitive noncoding sequences called telomeres that protect coding information from degradation during DNA replication.

centromere

Hardy-Weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time p + q = 1 : Applies to a gene with only two alleles (S and S), where p represents the frequency of one allele (S) and q represents the frequency of the other (s) P^2 + 2pg + q^2 = 1: Can be used to calculate frequencies of possible genotypes (SS, Ss and ss) from the allele frequencies. ere, p2 and q2 represent the frequencies of the two homozygous genotypes SS and ss, respectively. The frequency of the heterozygous genotype (Ss) is 2pq.

SER

contains no ribosomes along its surface, instead the interior compartment lumen of the SER contains enzymes that SYNTHESIZE LIPIDS (including cholesterol and cholesterol derived molecules (steroid hormones)

Any given strand of MRNA has three possible reading rames

depending on which nucleotide is in the first codon

The large intestine contains a diverse array of bacterial species (ie, gut flora) that aid in

digestive processes. some of these bacteria can process food items that would otherwise be indigestible, such as certain carbohydrates. Gut bacteria metabolize these undigested carbohydrates into short-chain fatty acids that can then be absorbed and used by the body for energy. In addition, some bacterial species in the large intestine synthesize certain vitamins.

Electrical vs chemical synapses

electrical synapses occur when the cytoplasms of two cells are joined by gap junctions. If two cells are joined by an electrical synapse, an action potential will spread directly from one cell to another. Not common in the nervous system, common in smooth and cardiac muscle chemical synapses are found at the ends of axons where they meet their target cell; here an action potential is converted to a chemical signal. Common in the nervous system and neuron-> skeletal muscle transmission

Scientists studying evolution in yeast found that a certain species underwent a reduction in chromosome number with no loss of coding information. How did this happen?

end-to-end (telomere-to-telomere) fusion of two chromosomes and inactivation of one of the centromeres. This fusion would initially generate a larger chromosome with two centromeres, and inactivation of one of these centromeres would produce a single new chromosome, reducing the chromosome number in the cell by one breakage of a chromosome at the centromere and fusion of each chromosomal portion to the ends of other chromosomes. This initial breakage would result in two individual chromosomal portions. Fusion of these portions to other chromosomes would cause the original chromosome to be lost, also reducing the overall chromosome number in the cell by one

Cells constantly take up matter from their surrounding environments by

endocytosis --> in which the surroudnings are enveloped by a portion of the cell membrane that portion subsequently pinches off from the rest of the membrane and becomes a vesicle inside the cell. This vesicle then matures and merges with other membrane-bound compartments to become an endosome. Cells can conduct endocytosis through three major mechanisms: phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Recombination is the exchange of genes between homologous chromosomes and always produces two recombinant chromosomes. Because each chromosome is equally likely to be passed on, recombinant genotypes always occur with ____ frequency, regardless of genetic distance.

equa;

The arrival of an action potential at the axon terminal of the presynaptic motor neuron triggers release of ACH from presynaptic vesicles into the synaptic cleft via

exocytosis. The ACh diffuses across the synaptic cleft to bind nicotinic ACH receptors (nACHRs) embedded within the membrane of the postsynaptic muscle fiber, eventually leading to muscle contraction.

The phospholipid bilayer of the cell membrane has an outer leaflet that interacts with the

extracellular environment and inner leaflet that interacts with the cytoplasm of the cell

%increase

final - initial /initial * 100

Centrosomes and Centrioles

form mitotic spindle; needed to form cilia and flagella

Corticosteriod hormones are secreted by the adrenal cortex

glucorticoids (eg cortisol): increase energy availability by stimulating lipolyisis and gluconeogenesis Mineralcortioids: (aldesterone)

THE RER

has ribosomes located along its surface --> translates the mRNA of proteins destined for the secretory pathway.

Lipid rafts

high in cholesterol content

The excess fluid in this patient's lungs (ie, pulmonary edema) is the result of an increased volume of blood flowing through pulmonary capillaries, which increases

hydrostatic pressure exerted on capillary walls. High hydrostatic pressure increases the rate of fluid leakage into the interstitial space surrounding pulmonary capillaries, causing excess fluid accumulation in the lungs.

Dendritic Cells

identify foreign pathogens, present antigen and activate other immune cells

Sweat glands are found

in the DERMIS OF THE SKIN Sweat glands in the dermis of the skin secrete sweat, which is a mixture of water, salts, trace nitrogenous waste, and antimicrobial proteins. Sweat is deposited on the surface of the epidermis via ducts that travel through the dermis and epidermis.

Cytotixic T cell (adpative immunity)

induce apoptosis in cells infected by pathogens

The posterior lobe of pituitary

made up of axonal projections from the hypothalamus, stores and secretes the hormones oxytocin and vasopressin (also called antidiuretic hormone [ADH]). Posterior pituitary hormones are synthesized in hypothalamic neurons and then transported down the axon to the axon terminals in the posterior pituitary, where they are stored. The secretion of stored hormones from the posterior pituitary is mediated by action potentials that cause exocytosis of neurosecretory vesicles.

In Eukaryotes, reproductive cells are produced via

meiosis, during which a diploid (2n) parent produces four genetically distinct haploid (n) daughter cells.

The force-generating step in muscle contraction occurs when

myosin pulls on actin,

quaisent cells

non-dividing cells who are in G0 phase of the cell cycle and therefore do not have organized kineotchores because the chromosomes are uncolied and relatively unstructured in this phase.

Pinocytosis

non-specific process that involves the continous invagination of the cell membrane to take up extracellular fluid.

Transcription in eukaryotes occur in

nucleus and mitchondria which are both membrane enclosed organelles

Ooogenesis begins before birth not a puberty

ooogonia(stem cells) under mitosis to produce (primary oocytes). Priamry oocytests must undergo meisos to mature but thuse oocytes become arrested at prophase I of meisos I until puberty. AT puberty, one primary oocyte is selected during each menstrual cycle to complete meisos I. unlike spermatogeneiss, meisos I in oogenesis yields two haploid cells of UNEQUAL size, the larger being secondary oocyte and the smaller one being a polary body that eventually degenerates. The secondary oocyte then beings meiosiis II but is arrested at metaphase II. To be fertilized, the secondary oocyte must be released during the ovulation pahse of the menstrual cycle. During this phase, the folicle ruptures form the ovary and the oocyte enters the fallopian tube to be fertilized by mature sperm.

Bacteria typically have cell walls surrounding the plasma membrane. These cell walls are composed largely of

petidoglycan = 1 layer crystal violet crosses the petidoglycan rich wall during Gram staining

The seminiferous tubules also contain specialized "nurse cells" called Sertoli cells that are responsible for

providing nutrients to sperm cells as well as regulating cell development.

DNA has deoxyribose sugars but RNA has

ribose sugars

water-soluable hormones cannot diffuse across the plasma membrane, and instead influence cellular activity by binding extracellular surface receptors to initiate a

second messenger cascade

The movement of food along the GI tract occurs via peristalsis, the coordinated contraction of muscle tissue lining the intestine walls.

smooth

Spermatogenesis

some of the daughter cells produced from mitotic divisions because primary spermatocytes primary spermatocytes because mature sperm via meiosis I and Meosis II. A primary spermatocyte that undergoes meisos I yields tow identical haploid cells labeled secondary spermatocytes. Each secondary spermotcyte then udnergoes meisos II to produce four haploid spermatids that are approximately equal in size to each other and develop into mature SPERM.

Sarcoplasmic reticulum

specialized endoplasmic reticulum in muscle fibers that is responsible for tightly regulating intracellular calcium concentration by sequestering calcium ions during periods of RELAXATION and releases them in the cytosol during periods of CONTRACTION (in response to ACP.

Innervation of the adrenal medula by the autonomic nervous system is unique because the adrenal medulla is only innervated by the

sympathetic nervous system.

Depending on the neurotransmitters effect on the post-synaptic neuron, synapses can be classified as excititory of inhibitory

t an excitatory synapse, the pre-synaptic neuron releases neurotransmitters that cause an influx of positively charged ions (Na+) into the post-synaptic neuron. These ions cause the resting membrane potential of the post-synaptic neuron to become more positive, or to depolarize, which promotes AP initiation. In contrast, inhibitory synapses release neurotransmitters that affect the post-synaptic neuron by causing either an influx of negative ions (Cl−) or an efflux of positive ions (K+). The exit of positive ions or entry of negative ions into the post-synaptic neuron causes the cell's membrane potential to become more negative, or to hyperpolarize, which inhibits AP initiation.

Desmosomes provide

tensile strength to epithelial cell sheets by anchoring the cytoskeletons, specifically the intermediate filaments of two cells

Endothelial cells are specialized type of epithelial cells that line the inside of

the heart, blood vessels and lymph vessels. THEY DO NOT line the lumen of the gastrointestinal tract

neutral theory of molecular evolution

the majority of genetic mutations are neutral, which means that they do not affect the fitness of an organism. Within species, these neutral mutations are randomly fixed or lost due to genetic drift and occur at a fairly constant rate over time. After two species diverge (separate), the accumulation rate of neutral mutations in a region of homologous DNA is mostly similar in both species. Accordingly, this "molecular clock" of evolution is said to be linear because the number of neutral mutations generally increases with time. For example, species that diverged more recently from a common ancestor have accumulated fewer mutations across a shorter time and are therefore more genetically similar to one another (ie, more closely related). In contrast, species that diverged less recently (eg, longer ago) from a common ancestor have accumulated more mutations across a longer period and are less genetically similar to one another (ie, less closely related).

The resting membrane potential is (-70 mV) of the post synaptic neuron. An AP is initiated in the post-synaptic neuron only if

the membrane potential become smore positive and exceeds a certain threshold of -55mv.

B-lymphocytes remain inactive until

their cell surface receptors bind a specific foreign antigen, which activates the lymphocyte Subsequently, the B-lymphocyte takes up the antigen via endocytosis and breaks it into smaller fragments. These fragments are then bound by specialized proteins called major histocompatibility class II (MHC II) proteins and presented on the surface of the B-lymphocyte. Subsequently, other immune cells can bind the foreign antigen, releasing cytokines (signaling molecules) that stimulate the proliferation of B-lymphocytes. These new B-lymphocytes fall into two categories: short-lived plasma cells that secrete antibodies, and long-lived memory B-lymphocytes that can recognize the same foreign antigen more rapidly in the event of a future encounter by the immune system.

If two genes are located close together on a chromosome (measured in centimorgans, or map units), are they likley to be seperated vy a recombination event?

they are relatively unlikely to be separated by a recombination event This is because there is less distance between the two genes in which a recombination can occur. Therefore, substantially fewer progeny will have recombinant combinations than parental combinations. As a result, the recombinant progeny can be identified by the fact that there are fewer of them. Table 1 shows that only 43 of 500 flies (~9%) were recombinant. Given this small percentage of recombinant flies, it is likely that the PTP and Abl genes are close together on the chromosome.

Adrenal Medulla is inverted by sympathetic neurons

this stimulates adrenal medullary cells to secrete norepinephrine and epinephrine which can act to increase sympathetic responses (eg, blood pressure increases)

HEART RATE is tightly regulated by the SA and AV node. Explain moroe

through cardiac muscle cells of the atria, inducing atrial contraction and ventricular filling. At the AV node, relay of APs to ventricular cells is delayed, ensuring that ventricular filling is complete prior to ventricular contraction. Next, APs travel through both ventricles, causing them to contract and expel blood into the arteries

secretory pathway/protein processing

translation of mRNA to proteins always begins in the cytosol, but proteins intended for the secretory pathway have an N-terminal sequence called the signal sequence. Once the signal sequence is recognized, the ribosome is transported to the RER where the protein is either translocated across the RER (secreted proteins) or embedded into the membrane (integral membrane proteins) In RER: post translational modifications may occur (i.e glycosylation, disulfide bond formation, phosphorylation, protein cleavage. The RER then packages proteins into veesicles and sends them to the GOLGI apparatus where they are further processed. Finally the Golgi packages proteins destined for the plasma membrane into secretory vesicles which fuse w/ the plasma membrane. Protiens that were initally embedded in the RER membrane frequently end up embedded in the plasma membrane as receptor proteins.

Basophils

type of granulocyte, is to release chemical mediators such as histamine that enhance the immune response. Released histamine causes vasodilation and permeability of vessels, which stimulates inflammatory response by increasing blood flow and the delivery of immune cells ( neutrophils and macrophages at the site of infection.

Digestive Protellytic Enzymes

which hydrolyze polypeptides are synthesized and secreted from the pancreas, stomach and small intestine.

All organisms undergo senescence

which is a a natural aging process during which cells and tissues acquire damage (eg mutations). Over time, this aging process cause cells to diminish in function

Blood flow through the circulatory system is affected by blood pressure, vascular resistance (VR, force opposing blood flow through a vessel), and cardiac output (CO, blood volume expelled from the ventricles per unit time). The relationship of these factors in the systemic circulatory system is given by

ΔP = CO × VR.

cillia

*Tiny hairlike extensions* that move together in a sweeping motion

systemic circuit

1. oxygenated blood containing nutrients to all body tissues via the arteries 2. when oxygenated blood reaches the capillaries, it delivers 02 (becomes deoxygenated) and nutrients to the tissues and picks up C02. Veins then return the deoxygenated blood (low 02, high C02, high H+) back to the heart so that it can enter the pulmonary circuit.

Pulmonary circuit

1. pumps deoxygenated blood through the pulm arteries to capilaries to facilate gas exchange. The capillaries are in close contact with lung alveoli (air saces) and at this site, the blood becomes reoxygenated (02 is transfered from alveolar air to the blood and c02 is transferred from the blod to alveolar air. 2. The pulmonary veins then return the oxygenated blood to the heart so that it can be pumped through the systemic circuit.

What is a eukaryotic cells cytoskeleton

A eukaryotic cell's cytoskeleton is an intracellular scaffolding (network) of fibers interspersed throughout the cytoplasm. The cytoskeleton is composed of three types of fibers: Microfilaments, intermediate filaments, and microtubules. Together, these fibers function to organize cellular components, support cellular motility (eg, cell movement, intracellular transport), and give the cell its shape.

neuromuscular junction (NMJ) and Acetylcholine

ACH = main neurotransmitter released by the EFFERENT SOMATIC nervous system, the system associated with skeletal muscle function Contraction of Skeletal muscle is stimulated by transmission of a nerve impulse at the neuromusclular junction, the synapse between a skeletal muscle and motor neuron. When an action potnetial reaches the terminal of a motor neuron, the influx of calcium through VOLTAGE GATED CALCIUM CHANNELS triggers the release of ACH-containing vesicles (exocytosis) into synapti cleft. Release ACH binds to receptors of the motor end plates, depolarizing the innerverated muscle and causing muscle contraction. AT the neuromuscular junction, ACH is released via exocytosis from presynaptic MOTOR neurons. Acetylcholine binds to receptors on the motor end plate triggering muscle ocntraction. Disruption of this process causes skeletal muscle paralysis.

lytic life cycle

Attachment: The bacteriophage contacts the bacterial cell wall and attaches to the host bacterium using its tail fibers. Viral genome entry: The phage uses its tail sheath to inject its genome into the cytoplasm of the bacterial host Host genome degradation: Viral enzymes degrade the host genome into its nucleotide components to provide the building blocks for replication of the viral genome Synthesis: Loss of the bacterial (ie, host) chromosome ends the synthesis of host molecules, now under the control of the viral genome. As a result, the host machinery (eg, ribosomes) begins to synthesize the components needed for new viral progeny, which then assemble inside the host cell. Release: Many newly assembled viral progeny (virions) are released as the bacterium disintegrates (lysis) due to the action of lysozymes on the host cell wall.

Divisions of the Nervous System

CNS PNS PNS divides into MOTOR AND SENSORY DIVISION SYSTEM MOTOR = nerve fibers transmit impulses from CNS to peripheral tissues SENSORY = nerve fibers transmit impulses to the CNS MOTOR IS DIVIDED INTO SOMATIC AND AUTONOMIC - SOMATIC: motor nerve fibers transmit impulses form CNS to skeletal muscles (voluntary) - Autonomic System - Visceral motor (involuntary) nerve fibers transmit impulses from CNS to cardiac/smooth muscles and glands AUTONOMIC IS DIVIDED INTO PARASYMPATHETIC AND SYMPATHETIC

BICARBONATE REACTION

CO2 + H2O <-> H2CO3 <-> H+ + HCO3- c02 and H+ go hand in hand

Conjugation

Conjugation is the transfer of genetic information from one bacterial cell to another via direct contact. The donor cell contains the F (fertility) factor plasmid, a circular piece of DNA containing genes that direct the formation of the sex pilus. During conjugation, the sex pilus from the donor cell attaches to a recipient cell (one that does not contain F factor) and facilitates the transfer of a single strand of the F factor plasmid DNA to the recipient cell. The recipient then synthesizes a complementary strand and becomes capable of passing genetic information to another bacterium. The F factor plasmid is typically found outside the bacterium's genome, but it can integrate into the bacterial chromosome. When integration occurs, bacterial genes can be transferred with the F factor.

contraction of arrector pili muscles

Contraction of arrector pili muscles causes piloerection, or upright standing of hairs, in response to sympathetic stimulation in cold environments. Therefore, this would not be a thermoregulatory response to increased temperatures.

Maturation off egg vs Sperm at Birth

During fertilization, the egg and sperm form a zygote with a nucleus containing the full complement of 46 chromosomes. These 46 chromosomes are found in pairs, and in each pair one chromosome comes from the mother and one comes from the father. Accordingly, egg and sperm cells are similar in ploidy because they both are haploid cells and contribute the same number of nuclear chromosomes to a zygote.

Sperm Size copareed to egg

During fertilization, the egg and sperm form a zygote with a nucleus containing the full complement of 46 chromosomes. These 46 chromosomes are found in pairs, and in each pair one chromosome comes from the mother and one comes from the father. Accordingly, egg and sperm cells are similar in ploidy because they both are haploid cells and contribute the same number of nuclear chromosomes to a zygote.

Euchromatin

Euchromatin forms when histones are modified, often by acetylation of lysine residues. The added acetyl group neutralizes the positive charge on a lysine residue, reducing interactions between histones and DNA. The reduced interactions yield a more open form that is more accessible to RNA polymerase, allowing euchromatin to be more readily transcribed.

The large intestine contains many bacterial species such as ______ that aid in the digestive processes.

Gut Flora Some of these bacteria can process ingested foods that would be undigestible otherwise (i.e certain carbohydrates) into molecules (eg short-chain fatty acids) that can be absorbed by the body and used for energy. Other bacterial species in the large intestine synthesize certain vitamins. Takeaway: - Bacterial species found in the large intestine perform functions important to digestive health, including vitamin synthesis and aiding in the digestion of certain ingested food that would otherwise by undigestible.

Habitat and Bacteria

Habitat refers to the natural environment in which an organism resides. Classification according to habitat typically uses the suffix -philes. Bacteria tend to inhabit numerous environments; for example, some bacteria can be thermophiles (comparatively high temperatures), acidophiles (low pH), or halophiles (high salt).

In prophase 1 of meiosis, what happens

Homologous chromosomes line up side by side during SYNAPSIS. Because each homologous chromosome consists of two identical chromatids, the adjacent chromosomal alignment forms a TETRAD (four chromatids in total). Tetrads arise when a synaptonmeal complex (protein structure) form between homologous chromosomes and hold the, together tightly. leads to increased genetic variation thus the offspring that develops after fertilization is genetically different from each parent, leading to increased genetic variation

Microtubules are made of alternating alpha and beta tubulin subunits, which assemble into hollow tubes

In addition to their involvement in cell ovment as part of the cytoskeleton icrotubules are also involved in cell motility forming the core of cilia and flagella and the formation of the mitotic spindle during cell division

Glomerular Filtration Rates and Stenosis

In the kidney's nephrons, circulating blood enters the glomerulus through the afferent arteriole and exits through the efferent arteriole. The degree of vascular constriction of these two arterioles controls the rate of blood flow into and out of the glomerulus, thereby affecting the volume of fluid filtered through the kidney per unit time, known as the glomerular filtration rate (GFR). Glomerular hydrostatic (blood) pressure contributes to blood filtration, forcing excess fluid and waste products (filtrate) across the porous endothelium and into Bowman's space. In general, proteins and cells are too large to pass through the pores, and the osmotic influence of proteins on fluid movement into and out of blood vessels is referred to as oncotic pressure. According to the question, stenosis is an abnormal narrowing of a blood vessel, a condition that mimics the physiological effect of vasoconstriction. As a result, afferent arteriole stenosis would limit the amount of blood flow through the glomerulus, causing decreased glomerular hydrostatic pressure and, consequently, decreased GF

Normal functions of the liver are

Ketogeneis: synthesis of ketone bodies During times of fasting, mitochondria within the liver cells convert acetyl coenzyme A into ketone bodies, which are then used by the brain to make ATP Detoxification of Drugs ---> facilitates breakdown and detoxification of many drugs SYNTHESIS OF PLASMA PROTEINS ---> oncotic pressure causes a pulling force inside the capillaries, which balances the pushing force of hydrostatic pressure, helping keep fluid in the vasculature. The majority of plasma proteins such as albumin are synthesized in the liver. Regulation of blood glucose via multiple g pathways storage of glycogen, minerals (iron) and vitamins Production and secretion of bile

gap junctions

Mediate communication between cells. Protein channels (connexions) in one cell align with complementary channels in another cell to form pores that facilitate the passive and bidirectional exchange of ions and small solutes. Gap junctions are found in cell populations that depend on coordinated activity, such as smooth muscle, cardiac muscle or neural tissue.

itchondria undergo self-replication

Mitochondria are organelles with important functions in aerobic cellular respiration. A mitochondrion is made of two layers formed by two membranes: an outer membrane and a folded inner membrane, the latter of which contains structures essential to the electron transport chain. Between the two membranes is the intermembrane space, and within the inner membrane is the matrix. Pumping of protons to the intermembrane space from the mitochondrial matrix provides the force necessary to generate ATP during oxidative phosphorylation. In addition, mitochondria can release enzymes from the electron transport chain to initiate apoptosis in a cell. Mitochondria are somewhat different from other membrane-bound organelles and can be considered semiautonomous. For example, mitochondria contain their own genes and have ribosomes for protein synthesis. Mitochondria are also able to replicate via binary fission in a process that does not directly involve the cell's nucleus. The passage states that cisplatin is a chemotherapy drug that can lead to nephrotoxicity by promoting excessive fission of mitochondria in renal tubular cells. Therefore, cisplatin most likely directly influences mitochondrial self-replication

Peristalsis

Moves ingested food from the mouth through the gastrointestinal tract and consists of several components. 1. The esophagus is a hallow tube that moves ingested food form the mouth to the stomach as a bolus (i.e compact food mass) 2. In the stomach, the bolus is CHEMICALLY AND MECHANICALLY digested, creating a semifluid substance called chyme which moves into the small intestine 3. The small intestine is a long tube with 3 subdivisions, the duodenum, jejunum and ilium in which MACROMOLECULAR digestion is completed and substances useful to the body are absorbed. Absorption occurs across the epithelial cell lining the small intestine. Any undigestible material passes to the large intestine. - NOTE IN SMALL INTESTINE, Nutrients move across epithelial cells during absorption by the body 4. In the large intestine, water and electrolytes are absorbed from indigestible material to form solid feces.

The esophagus serves only to move ingested food from the mouth to the stomach.

No absorption or digestion occurs in the esophagus.

parathyroid hormone

Parathyroid hormone, released from the parathyroid glands in response to low blood calcium levels, works to promote several responses to elevate blood calcium levels. If excess calcium losses in sweat caused a reduction in plasma calcium concentration, parathyroid hormone might be released as a response to (but not a mediator of) sweating.

Ploidy is defined as the number of homologous chromoses set in the cells.

Ploidy is defined as the number of homologous chromosome sets in the nucleus of a cell. In the human body, with the exception of sperm and egg cells (reproductive cells), nucleated cells are diploid and known as somatic cells. Somatic cells have 46 individual chromosomes that appear as 23 pairs. Each somatic cell has two sets/copies (2n) of each chromosome. These include 22 pairs of homologous chromosomes (autosomes) and 1 pair of sex chromosomes.

Bile

Produced by the Liver, Stored in the Gall Blander Released into the Small Intestine to help MECHANICALLY ( by non enzymatic and nonchemically means) digest lipids. Bile salts one component of the bile, break down large lipid globules into miscells ( smaller dropletS) during emulsification.

The following mechanisms contribute to maintenance of the resting membrane potential:

Protein channels in the cell membrane enable certain ions to move down their concentration gradient across the membrane. - For example, in resting neurons, potassium (K+) leak channels help maintain the membrane potential by enabling the passive transport (without using energy) of K+ out of the cell. The membrane is more permeable to K+ than to Na+ (ie, selective permeability) due to the presence of a greater number of K+ leak channels. Therefore, the resting membrane potential of neurons is approximately −70 mV, which is close to the negative equilibrium potential of K+ Active transport pumps embedded in the outer membrane of neurons hydrolyze adenosine triphosphate (ATP) to provide energy to transport molecules against their concentration gradient. For example, sodium-potassium pumps (Na+,K+-ATPase) transport 2 K+ into the cell for every 3 Na+ moved out. This is important for maintaining the unequal concentration of ions across the membrane; without active transport pumps, leakage of ions through the cell membrane would eventually result in equilibration and a membrane potential of 0 mV (Number so protein channels allow passive transport of certain ions down their electrochemical gradient active transport helps maintain the concentration gradient and are critical for maintaining the resting membrane potential.

RNA polymerases and transcription factors function

RNA polymerases are responsible for carrying out transcription and must bind DNA at a promoter region for transcription to be initiated. Transcription factors are proteins that can bind to DNA near gene promoter regions and either increase transcription (activators) or decrease transcription (repressors). Activators facilitate RNA polymerase binding to the promoter, and repressors inhibit binding.

Substances are filtered through the glomerular capillaries by

SIZE

Sebaceous glands and Pilosebaceous units (PSUs)

Sebaceous glands associated with hair follicles make up pilosebaceous units (PSUs). Like sweat glands, PSUs are exocrine glands that deposit their product (ie, sebum) on the skin surface.

Pepsinogen

Site of Secretion: Chief Cells Site of Function: Stomach Function: zymogen of pepsin cleaves polypeptides into smaller peptides when activated by the low pH of gastic juice.

Procarboxypeptidase

Site of Secretion: Pancreas Site of Function: SI Function: zymogen of carboxypeptidase, which when activated cleaves the terminal peptide bond at the C terminus

Trypsinogen

Site of Secretion: Pancreas Site of Function: Small Intestine Function: Zymogen (inactive form) of trypsin, which when active converts chymotrypsonigen and procoboxypeptidase into their active forms

Chymotrypsinogen

Site of Secretion: Pancrease Site of Function: Small Intestine Function: Zymogen of chymotrypsin, when when activated cleaves specific peptide bonds of polypetide

Somatostatin

Somatostatin, released by pancreatic delta cells, has a generalized inhibitory effect on the functioning of the digestive system. Somatostatin can also suppress the release of insulin and glucagon from the pancreas

The endocrine pancreas vs exocrine pancrea

The endocrine pancreas secretes hormones involved in the regulation of blood glucose into the bloodstream, while the exocrine pancreas secretes digestive enzymes and bicarbonate into the small intestine to assist in digestive processes and to neutralize the acidity of chyme.

which cells are largely responsible for the skin's relative impermeability to water loss.

The most superficial layer of the epidermis, the stratum corneum, is composed of many layers of keratinocytes that have been pushed up from the deeper layers and flattened in the process. These flattened keratinocytes create a barrier to invasion by external pathogens and help prevent water and salt loss through the skin surface. Therefore, the skin is relatively impermeable to water loss largely due to the cells of the stratum corneum.

Skin layers

The skin can be divided into three major layers, the epidermis, the dermis, and the hypodermis. The epidermis is further divided into five additional layers known as strata. From superficial to deep, these layers include the stratum corneum, stratum lucidum (only present in thick skin of the palms and foot soles), stratum granulosum, stratum spinosum, and stratum basale.

stratum basale

The stratum basale is the deepest layer of the epidermis and consists of a single layer of stem cells that divide continually to give rise to new stem cells.

Where is the liver located?

The upper right side of the abdominal cavity, below the diaphragm and performs various functions within the body.

Transduction

Transduction involves DNA transfer from one bacterial cell to another by a bacteriophage (a virus that infects bacteria). During assembly of bacteriophages inside an infected cell, bacterial DNA can become trapped within the capsid of newly created bacteriophages. Subsequent infection of other cells with these new bacteriophages results in the transfer of bacterial DNA into a new host. Neither of the experimental E. coli cultures was exposed to bacteriophages.

Transformation

Transformation is the cellular uptake of foreign DNA directly from the environment

Western Blot

Western blot is a laboratory technique that first separates proteins by size (gel electrophoresis) and then transfers them to a blotting membrane. A primary antibody specific for the protein of interest is used as a probe. The membrane is washed to clear unbound antibodies and then treated with a secondary antibody that specifically binds to the primary antibody. Depending on the type of secondary antibody used, detection of the proteins of interest is achieved either by fluorescence or by a reporter enzyme. In general, proteins with the shortest amino acid sequences have lower molecular weights and migrate quickly through the gel. Band intensity (thickness) demonstrates the relative levels of expression of the target proteins.

Increased temperatures trigger sweat production and vasodilation of surface capillaries

When body temperature increases above normal levels, the hypothalamus coordinates responses to decrease body temperature. These responses include the production of sweat, a hypotonic solution secreted onto the skin surface via glands. When the water in sweat evaporates, heat is lost and the body cools. In addition, surface capillaries undergo vasodilation, allowing blood in capillaries to transfer heat from the body to the environment. When body temperature decreases below normal levels, the hypothalamus coordinates responses to increase body temperature. One response is shivering, which generates heat in the body via contractions of skeletal muscle. In addition, surface capillaries undergo vasoconstriction to minimize heat loss to the environment from the blood.

Norepinephrine and Epinephrine

acid-derived hormones and are released from ADRENAL MEDULA sympathetic nervous system

transcription factors

can up-regulate or down-regulate transcription by influencing the ability of RNA polymerase to bind a promotor. Transcription factors that increase transcription are called activators and facilitate RNA polymerase binding whereas those that decrease transcription are called repressors and inhibit binding.

Absorption of lipids and other macromolecules is complete by the time

ingested food reaches the end of the small intestine. Subsequently in the Large Intestine, WATER and Electrolytes (not LIPIDS) are absorbed.

Epinephrine

is a hormone released by the adrenal medulla in response to a stressor. Epinephrine release leads to redirection of blood flow in the body via vasoconstriction and vasodilation, increased heart rate, dilation of bronchioles, and sweat release. These are hallmarks of the "fight-or-flight" response of the sympathetic nervous system

The final portion of the gastrointestinal tract is the

large intestine, a wide tube consisting of three subdivisions, the cecum, colon and rectum. The colon is further subdivided into four sections: the ascending colon, transverse colon, descending colon and sigmoid colon, from proximal to distal. In the large. intestine, water and electrolytes are absorbed from undigestible material to form solid feces. note as undigestible materials move through the large intestine, peristaltic contraction speed decreases. so it is greatest in cecum and least frequent in the sigmoid colon

ENDOTHELIUM (explain)

one cell thick layer of epithelial cells (endothelial cells) that line the interior of the cardiovascular system this layer of cells is in direct contact with the blood in the lumen (inner cavity and provides a relatively smooth, frinction reducing surface that enables the efficient oveent of blood through the vasculature. ENDothelium also acts as a barrier that regulates the exhcnage of substances between the blood and nearby tissue. For isntance in response to inflammatory chemicals released during an infection, endothelial cells faciliate teh ovent of white blood cells out of the bloodstream to the affected tissue.

The portion of the chromosome that interacts with the kinetochore during mitosis is the centromere. Along the centromere contains heterochromatin

s heterochromatin

Epithelial cells are packed together tightly into sheets that make up the outer layer of the skin (the epidermis) and also make up the

secretory components of glands, the lining of the inner cavities of the body (i.e hollow organs such as gastrointestinal tract)

In arteries and veins, the interior of endothelial cells is surrounded by a layer of

sooth muscle contraction of smooth muscle -- results in vasoconstriction which promotes increased blood pressure relaxation of the smooth muscle results in vasodilation and decreased blood pressure. the endothelium itself does not contract, rather smooth muscle contraction is regulated by factors i.e autonomic nervous system, renin and angiotensin, and factors derived form the endothelium.

Although some water is lost through sweat glands at the skin surface, the skin is relatively impermeable to water loss largely due to the cells of the:

stratum corneum

Osmoregulation by the kidneys as water intake increases

when large amounts of water are consumed, the osmolarity of the blood decreases. To maintain homeostasis in this situation, higher concentrations of solutes (eg, sodium ions) will be reabsorbed, while more water will be excreted by the kidneys, producing a larger volume of dilute urine. In this way, the concentration of water and solutes in the blood stays relatively constant.