UWorld Biology

what hormone do anterior pituitary secrete

GH, TSH, LH, FSH, ACTH, prolactin - LH and FSH stimulate follicle maturation, ovulation, and estrogen production in females and spermatogenesis in male - these hormones main function are metabolism and reproductive fxn - tropic hormone (act on other endocrine gland): TSH, ACTH, LH, FSH direct hormone: GH, prolactin, and endorphin

Which proteins identified in Figure 2 have the shortest amino acid sequence and the greatest concentration in WT cells, respectively? ** pic on 1. in word doc A.EspA, Tir B.Tir, EspB C.EspB, EspA D.EspB, EspD

Tir protein traveled farthest, so it has low molecular weight and shortest amino acid sequences EspB has intense band, so it has the greatest concentration correct answer is B

elastic cartilage

cartilage with abundant elastic fibers; more flexible than hyaline cartilage - Highly flexible; withstands distortion without damage & reverts to its original shape (eg, external ear)

Bottlenecks event

catastrophic event (human action or environ event) that drastically decreases population size and genetic diversity

Gap junctions

cell-cell junctions that mediate communication between cells - found in cell populations that depend on coordinated activity, such as smooth muscle, cardiac muscle, or neural tissue

Tight junctions

cell-cell junctions that prevent water and solutes from diffusing between cells and across the epithelial cell layer - found in a number of tissues, including skin, gastrointestinal tract, and testis

Transformation

cellular uptake of foreign DNA from the environment. - This process is enhanced with increased cell membrane permeability (competence) that occurs in response to physical manipulation

The cheetahs that survived the environmental catastrophe that occurred 12,000 years ago are at greater risk of extinction because of: A.naturally selected changes in allele frequencies. B.random changes in allele frequencies. C.changes in allele frequencies due to migration. D.changes in allele frequencies due to random mating.

cheetahs experiences catastrophic event and their population decreased. Consequently, the smaller population of cheetahs has a reduced ability to buffer the negative impacts of random changes in allele frequencies (genetic drift) that may result in extinction. A, C, D are wrong b/c natural selection, migration, random mating can increases genetic diversity and increases fitness, which actually benefits the population and make them far from extinction correct answer is B

Chondrocytes

make up the cellular component of cartilage

start codon

AUG

Glycogenolysis

breakdown of glycogen to glucose

what happened when estrogen and progesterone stop secreting

1. the vaginal epithelium dehydrates -> causing discomfort and impairing sexual activity 2. changes in mood -> irritability, depression, anxiety, fatigue 3. the reproductive organs and breasts shrink (atrophy). 4. decreased bone density -> greater osteoclast activity 5. menstrual cycles will not occur

Given that scar tissue forms when collagen-producing cells replace normal tissue after an injury, all of the following processes would be impaired in the area of scarred skin that forms over a partial-thickness burn EXCEPT (partial thickness burn: damage epidermis and dermis) A.resistance to ultraviolet radiation.[30%] B.insulation.[42%] C.hair growth.[11%] D.salt excretion.[14%]

** read question carefully and find info in passage - UV radiation protection: Melanin, a dark pigment produced by epidermal melanocytes, absorbs and prevents UV light from damaging the DNA of other cells in the body -> melanin is transfered from melanocytes to keratinocytes -> epidermis is damaged - hair growth: Hair strands are composed of dead keratinized cells and are produced in the hair follicles, which are located in both epidermis and dermis -> both epidermis and dermis is damaged -> Fingernails, toenails, and calluses are keratinosized structure derived from skin - sale excretion: Sweat glands arise from the dermis and secrete sweat through duct in epidermis -> both epidermis and dermis is damaged - insulation: The subcutaneous layer of skin, also called the hypodermis, is composed of adipose tissue that buffers rapid fluctuations in body temperature by acting as a thermal insulator correct answer is B

A male patient was born with an abnormal opening in the muscular wall separating the two ventricles of the heart. The opening allows blood to flow from the left to the right ventricle. If left untreated, this cardiac defect may cause any of the following in the patient EXCEPT: A.increased blood flow into the pulmonary artery B.increased blood volume in the left atrium C.low blood oxygen levels in systemic arteries. D.reduced oxygenation of blood pumped into the pulmonary artery.

** the question is asking which would not occur when there is an opening between left and right ventricles oxygenated blood flow from left ventricle to right ventricle, so oxygenation of blood pumped into the pulmonary artery will actually increase, not decrease choice C is incorrect -> because oxygenated blood flow from left to right ventricle, there would be less blood pumped to systemic arteries correct answer is D

What physiological change occurs in the skin of control subjects during HA exercise (Heat acclimation (HA) is the process by which the body increases heat tolerance through adaptive changes in the sympathetic control of skin heat dissipation)? A.Enhanced contraction of arteriole smooth muscle[13%] B.Enhanced relaxation of arteriole smooth muscle[48%] C.Enhanced contraction of arrector pili muscles due to parasympathetic activation[4%] D.Enhanced contraction of arrector pili muscles due to sympathetic activation[32%]

**have the knowledge, but need to understand the question and passage. the control is exercising in a heated environment, so what happen when body temperature increase? - sweating and vasodilation to decrease body temperature - arrector pili muscle is (attached to hair follicle in the skin) would not contract in hot environ, but will contract in cold environment after receiving sympathetic signal to cause piloerection (hair standing upright) correct answer is B

glucagon

- secreted by pancreas - increase sugar level by breaking glycogen in liver

lacunae

- spaces containing osteocytes - connect to one another via canaliculi

how to interpret Lineweaver-Burk plots?

1. y-intercept = 1/Vmax; x-intercept = 1/Km 2. increase in the magnitudes of the intercepts corresponds to a decrease in Vmax (up) and Km (left shift)

Which of the following skin functions will most likely be impaired in tissue with superficial burns? I. Keratinocyte maturation II. Immune surveillance III. Shock absorption A.I and II only[42%] B.I and III only[25%] C.II and III only[15%] D.I, II, and III[16%

- stratum basale consists of a single row of stem cells that continually divide to give rise to new stem cells. Of the two daughter cells produced from each mitotic division, one cell remains in the basal layer (to continue proliferating) and the other begins differentiating into a mature keratinocyte. As constant cell division pushes the keratinocytes outward through the epidermal layers, they fill with keratin, flatten, and lose their organelles. - shock absorption and insulation are in hypodermis -Epidermal Langerhans cells are immune (dendritic) cells that recognize and ingest antigens before migrating to nearby lymph nodes to present these antigens to T cells, activating the adaptive immune response. correct answer is A

What is Kcat?

- the number of substrate molecules converted to product per second by each enzyme in solution under saturating conditions. - Vmax=Kcat(E)

what are the sensory receptor in dermis?

1. Meissner corpuscles: light pressure, low frequency vibration 2. Ruffini endings: stretch 3. Pacinian corpuscles: deep pressure, and high frequency vibration 4. free nerve ending: touch, temperature, chemical pain

what are the sensory receptor in epidermis

1. free nerve ending: touch, temperature, chemical pain 2. merkel disc: continuous pressure

how do we response to stress?

1. hypothalamus stimulates pituitary gland to release ACTH 2. then, adrenal cortex release glucocorticoid hormone, such as cortisol 3. cortisol mediates stress respond by increasing glucose level, decreasing protein synthesis and inflammation 4. when there are too much cortisol released, immunologic response is negatively impacted, increases susceptibility for disease, and reduce reproductive health

what is the function of enzyme?

1. stabilize transition state 2. decrease activation energy 3. increase rxn rate and rxn constant 4. wont affect energy diff btw product and reactant, so dG will not change 5. as dG is related to equilibrium constant (Keq), Keq will not change -> dG=-RTln(Keq)

A scientist studying the sequence of the homodimer of LPL would most likely expect that: * passage info: LPL homodimer to dissociate into two inactive 225-residue monomers A.675 mRNA nucleotides must be translated to form a fully functional 50-kDa LPL protein B.1,350 mRNA nucleotides must be translated to form a fully functional 50-kDa LPL protein C.675 mRNA nucleotides must be translated to form a fully functional 25-kDa LPL protein D.1,350 mRNA nucleotides must be translated to form a fully functional 25-kDa LPL protein

3 nucleotide = 1 codon = 1 amino acid 1 amino aicd = 110 Da 1350 nucleotides = 450 amino acid = 45000 Da = 45 kDa 675 nucleotides = 225 amino acids = 22500 Da = 22.5 kDa correct answer is B

Cartilage

A connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together. - lack vascular and nerve, so need nutrients and O2 via diffusion from surrounding fluids or vascularized areas

Southern blotting

A hybridization technique that enables researchers to determine the presence of certain nucleotide sequences in a sample of DNA and measure the concentration DNA in the sample tissues 1. DNA is isolated from other cellular components and cut into smaller fragments by restriction enzymes. 2. The purified DNA fragments are separated by size via gel electrophoresis and then denatured. 3. The DNA fragments are transferred from the gel to a blotting membrane and immobilized. 4. The membrane is incubated with a single-stranded DNA probe complementary to the DNA sequence of interest. If the sequence of interest is present, the probe will bind to it (hybridize). The label (eg, radioactive atom, fluorescent dye) allows visual detection of the probe. 5. The sample is washed to remove unbound probes. 6. Researchers determine if a visual signal is present. A visual signal indicates that hybridization occurred, meaning the sample contained the DNA sequence of interest. No visual signal corresponds to absence of the target DNA sequence.

WT1 and c-Myc most likely alter TERT transcription levels by doing which of the following at the TERT gene promoter? A.Inhibiting and facilitating RNA polymerase binding, respectively B.Inhibiting and facilitating DNA polymerase binding, respectively C.Facilitating and inhibiting RNA polymerase binding, respectively D.Facilitating and inhibiting DNA polymerase binding, respectively

According to the passage, the presence of WT1 inhibit expression of TERT in cells, so it's an inhibitor. and the presence of c-Myc promote TERT expression, and it facilitates RNA polymerase binding. correct answer is A

Both isoforms of destabilase have approximately the same kcat values at optimal pH, but Figure 1 shows that when 5 μL of each purified enzyme was saturated with substrate, isoform 2 had substantially higher activity. What factor could explain this apparent discrepancy? A.The affinity column bound isoform 1 more tightly than isoform 2.[21%] B.Under saturating conditions, only isoform 2 operated at Vmax.[41%] C.Isoform 1 became denatured at the optimal pH of isoform 2.[9%] D.E. coli expressed isoform 2 at higher levels than isoform 1.[27%]

An enzyme's turnover number kcat is the number of reactions each enzyme catalyzes per second under saturating conditions. The maximum velocity Vmax of an enzyme-catalyzed reaction is equal to kcat multiplied by the concentration of enzyme [E]. Two enzymes with similar kcat values may have different Vmax values if one of the enzymes is present at a higher concentration than the other. B is wrong b/c under saturated condition, all enzymes are operated at Vmax correct answer is D

spleen

An organ that is part of the lymphatic system; it produces lymphocytes, filters the blood, stores blood cells (platelets and other WBC), and destroys old blood cells. also has immune response mounted by lymphocytes that against pathogens

Desmosomes

Anchoring junctions that prevent cells from being pulled apart - provide tensile strength to epithelial cell sheets by anchoring the cytoskeletons, specifically the intermediate filaments, of two cells together. - found predominantly in tissues that are subject to high levels of mechanical stress (eg, muscle tissue, epithelial layers of the skin) and prevent tissue tearing

The number of each type of sex chromosome in a group of 5 male (WT,XY) and 5 female (WT,XX) rabbits is shown below. In the combined population of 15 X chromosomes and 5 Y chromosomes, which of the following alleles, if any, would be most susceptible to loss due to random chance alone? A.An allele on the Y chromosome B.An allele on the X chromosome C.An allele on either the X or Y chromosome D.Allele loss due to random chance alone would only occur in nonsex chromosomes

Because the Y chromosome is present only in males, its population size is automatically smaller than that of the X chromosome. In addition, the passage states that the Y chromosome has fewer alleles, meaning that Y chromosome alleles will exist at lower frequencies than alleles on the X chromosome. Genetic drift is the fluctuation of allele frequencies within a population due to chance events - low-frequency alleles have an increased probability of being eliminated by random events than do high-frequency alleles - b/c Y chromosome exist at low frequency, they are more likely to loss Correct answer is A

What role do FSH and LH have in the onset of puberty

FSH: maturation and growth of follicle LH: stimulate follicle rupture and release of secondary oocyte near fallopian tube -> LH surge before ovulation

Lamellae

Concentric rings made up of groups of hollow tubes of bone matrix in compact bone

A scientist proposed that ectopic endometrial cells contain extra copies of the VEGF gene. Given this information, which of the following techniques can be used to analyze VEGF gene count? I. DNA sequencing II. Northern blot III. Southern blot A.I only B.II only C.I and III only D.II and III only

DNA sequencing and sourthern blot are used to assess gene count and directly analyze DNA correct answer is C

Sanger dideoxy method

DNA sequencing technique based on DNA replication that uses dideoxy nucleoside triphosphates - determine the nucleotide order of target DNA molecules.

Several techniques have been developed to treat blood disorders caused by genetic mutations. Which of the following methods would be most effective in the treatment of a patient homozygous for a deleterious mutation in a gene coding for a subunit of hemoglobin? A.Replacement of the mutant gene with a functional copy in red blood cells B.Treatment with a drug that increases red blood cell production C.Introduction and activation of a functional hemoglobin gene in bone marrow stem cells D.Single blood transfusion from a patient homozygous for the wild-type hemoglobin gene

Gene therapy is a technique in which a functional copy of a gene is introduced (eg, via retroviral vectors) into the cells of a patient with a mutation in that gene. 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 choice A is wrong -> The mutant gene could not be replaced by a functional copy in mature RBCs because mature RBCs lack nuclei and do not contain DNA. correct answer is C

Passage info: An example of an infectious disease is viral hepatitis (inflammation of the liver), which can be caused by any one of five distinct hepatitis viruses (A-E) that infect hepatocytes (liver cells). HAV, HCV, and HEV contain positive-sense, single-stranded RNA (+ssRNA) as genetic material. In contrast, HBV has a partially double-stranded circular DNA genome. HDV is unique because it has a negative-sense, single-stranded RNA (−ssRNA) genome. Researchers hypothesized that synthetic antibodies could be used to treat viral hepatitis in patients with compromised immune systems. Fluorescent antibodies, designed to bind the capsid proteins of the five hepatitis viruses, were added to separate wells containing each type of virus. The fluorescence assay that was performed detected only bound antibodies in media with HAV or HEV. Question: Based on the passage, which of the following viruses does NOT have an outer phospholipid bilayer? A.HBV[17%] B.HCV[3%] C.HAV[55%] D.HDV[24%]

In the passage, researchers determined whether hepatitis viruses were enveloped or non-enveloped by exposing each virus to fluorescent antibodies designed to bind viral capsid proteins directly. Therefore, depending on the presence or absence of fluorescence, researchers would be able to determine whether the virus is non-enveloped or enveloped, respectively. The fluorescence assay revealed that capsid proteins were detected only in media containing HAV or HEV. Because the antibodies were able to bind directly to the capsid proteins of both viruses, it can be determined that HAV and HEV are non-enveloped viruses (ie, they do not have a phospholipid bilayer enveloping the capsid). Correct answer is C

Calcitonin

Lowers blood calcium levels - secrete by thyroid gland when Ca level is too high - reduce osteoclast activity

Which step(s) of the viral life cycle would most likely occur in lytic phages? I. Injection of viral genetic material into the bacterial host II. Integration of viral DNA into the bacterial genome III. Degradation of the host genome A.I only B.III only C.I and II only D.I and III only

Lytic life cycle: 1. attachment - bacteriophage attaches to the host bacteria 2. viral genome entry - virus inject its genetic material to the host 3. host genome degradation - Viral enzymes degrade the host genome into its nucleotide components to provide the building blocks for replication of the viral genome 4. synthesis - host machinery is used to product viral components and assemble in the host cell 5. 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. viral genome will integrate to host genome in lysogenic cycle and going through cell division, which means viral DNA divide with host DNA correct answer is D

Helper T cells

One type of T lymphocyte enhances immune response that activates B cells, macrophage activity, and other T lymphocytes (cytotoxic T cells, which release toxins to induce apoptosis in infected cells) - will not affect MHC cells as it is depend on cell's transcription and translation machinery

The knockout mouse model and the constitutively active mouse model of ANGPTL4 are best represented by: ** table is 3. on word doc A.Profile 1 and Profile 2, respectively B.Profile 1 and Profile 4, respectively C.Profile 3 and Profile 4, respectively D.Profile 3 and Profile 2, respectively.

Per the passage, ANGPTL4 codes for angiopoietin-like 4, a protein that inhibits the action of LPL. The passage also states that LPL catalyzes the degradation of triglycerides (lipid molecules) in the blood. Consequently, expression of the wild-type ANGPTL4 gene, whose protein product inhibits LPL activity, leads to higher levels of triglycerides in the blood and therefore increases the risk for CAD. Profile 3 = knock out mouse = ANGPTL4 is absent = LPL level increase = triglyceride decrease Profil 4 = ANGPTL4 is active correct answer is C

If a man and a woman are having difficulty conceiving a child and decide to undergo ICSI treatment using their own gametes, which of the following represents the proper developmental pathway of the sperm cell selected to fertilize the egg during this procedure? A.Spermatogonium, spermatocyte, spermatid, spermatozoon B.Spermatogonium, spermatid, spermatozoon, spermatocyte C.Spermatocyte, spermatogonium, spermatozoon, spermatid D.Spermatocyte, spermatid, spermatozoon, spermatogonium

Spermatogonia (stem cell that undergo cell division to become mature cell) ---> mitosis ---> primary spermatocyte (2n) --> meiosis I ---> secondary spermatocyte (2n) ---> meiosis II --> spermatids (n) ---> spermatozoon (n, losing most cytoplasm) correct answer is A

how do body obtain vitamin D?

The body obtains vitamin D through dietary absorption in the intestine and through the ultraviolet light-mediated conversion of epidermal cholesterol into a vitamin D precursor.

Researchers concluded that captive cheetahs have reduced fitness because of their increased susceptibility to diseases. What can best explain the decreased fitness of captive cheetahs? A.Increased MHC diversity B.Decreased MHC diversity C.Increased environmental stress D.Decreased environmental stress

The data in the passage shows that captive male cheetahs have relatively higher susceptibility to diseases despite having increased genetic diversity. As a result, it can be concluded that other factors besides genetics determine the fitness of captive male cheetahs. Indeed, according to Figure 3, captive cheetahs have increased fecal cortisol levels (which is related to stress level). Therefore, the decreased fitness can be attributed to increased cortisol, which is a marker of increased environmental stress. high stress environment -> increased cortisol level -> reduce immunocompetance (increase susceptibility to disease) and fitness correct answer is C

p-value

The probability of observing a test statistic as extreme as, or more extreme than, the statistic obtained from a sample, under the assumption that the null hypothesis is true. - p > 0.05 signifies a greater than 5% probability that the observed result is due to chance alone, not due to an actual association between the variables under study. Values in this range are generally not considered statistically significant. - p ≤ 0.05 signifies a 5% or lower probability that the observed result is due to chance alone. Values in this range are typically considered statistically significant.

Which of the following helps maintain the resting membrane potential of a neuron? I. Passive transport II. Adenosine triphosphate III. Membrane selective permeability A.II only[9%] B.III only[8%] C.I and III only[32%] D.I, II, and III[49%]

The resting membrane potential of neurons is primarily due to the high concentration of potassium ions (K+) and the low concentration of sodium ions (Na+) inside the cell as compared to the outside. Mechanism contributes to maintain resting membrane potential: 1. protein channels enable certain ions to move down concentration gradient across the membrane -> potassium leak channels allow K+ move out of cell thru passive transport 2. selective permeability -> generate resting membrane potential in nerve and muscle cells -> membrane is more permeable to K+ than to Na+ => resting membrane potential = 70 eV is close to the equilibrium potential of K+ 3. active transport embedded in outer membrane -> hydrolyze adenosine triphosphate (ATP) to provide energy to transport molecules against their concentration gradient => ex: sodium-potassium pumps: pump 2 K+ ions in and 3 Na+ ions out -> maintain resting membrane potential and concentration gradient => w/o active transport, leakage of ions through the cell membrane would eventually result in equilibration and a membrane potential of 0 mV correct answer is D

hyaline cartilage

Translucent bluish white cartilage consisting of cells embedded in an apparently homogeneous matrix, present in joints and respiratory passages, and forming most of the fetal skeleton - Reduces friction between bony surfaces to facilitate joint movement - Allows linear bone growth at the epiphyseal plate in childhood - Reinforces respiratory passageways - Supports the external nose - bone template; gives rise to bone through endochondral ossification.

stop codon

UAA, UAG, UGA

canaliculi

allow osteocyte waste exchange and nutrient delivery.

Renal studies in mice have revealed that a mutation in various sodium transporters causes impaired active transport of NaCl from the filtrate within the loop of Henle to the medulla. If mice with wild-type sodium transporters were compared to mice with the mutated sodium transporters, the mutant mice would likely exhibit all of the following EXCEPT: A.decreased saltiness of the medulla.[9%] B.decreased urine output.[63%] C.decreased renal water reabsorption.[12%] D.decreased blood pressure.[14%]

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.Following passage through the loop of Henle, filtrate travels through the distal tubule into the collecting duct, where water and salt reabsorption continue. Remaining filtrate flows to the bladder and is excreted from the body as urine. -> think about ADH, which increase water reabsorption and blood pressure because of the mutation, active transport of NaCl is impaired, renal water reabsorption is reduced, so urin output increase correct answer is B

A single diploid cell containing 46 chromosomes underwent meiosis and produced four daughter cells, two with 22 chromosomes and two with 24 chromosomes. An error in which of the following stages of meiosis would most likely explain this result? A.Metaphase II B.Prophase II C.Telophase I D.Anaphase I

chromosomal nondisjunction occurs when either homologous chromosomes (during anaphase of meiosis I) or sister chromatids (during anaphase of meiosis II) fail to separate to opposite poles of the cell. meiosis stages: prophase -> metaphase -> anaphase -> telephase correct answer is D

what happened to Ach if it's not bound to Ach receptor?

diffuse away or destroyed by acetylcholinesterase

osteon/haversian system

entire unit of concentrically arranged lamellae surrounding a central haversian canal - structural unit of compact bone

Reporter genes

express easily identified (ie, fluorescent, luminescent) protein products and are consequently used to determine the effects of certain regulatory sequences or measure the expression of other genes.

Glycogenesis

formation of glycogen from glucose

Transfection

genetic material, usually in the form of a plasmid, is introduced into eukaryotic cells

A gene expression assay shows that the SRY gene is expressed in male embryos during the early stages of development. Which of the following best describes the DNA methylation pattern exhibited by the SRY gene in embryonic gonadal cells compared to embryonic cardiac cells? A.The SRY gene will have higher levels of methylation in embryonic gonadal cells. B.The SRY gene will have lower levels of methylation in embryonic gonadal cells. C.The SRY gene will have similar levels of methylation in both cell types. D.The comparison cannot be performed as cardiac cells do not carry the SRY gene

gonadal cells = euchromatin - more gene expression -> b/c euchromatin looser and the DNA more accessible to the transcription machinery - high levels of histone acetylation - low levels of DNA methylation cardiac cells = Heterochromatin - genes are silence b/c DNA are tightly packed so cannot access to transcription machinery - low levels of histone acetylation - high levels of DNA methylation SRY is present in both gonadal and cardiac cells. SRY gene is highly expressed in gonadal cells as it is important in male sexual development. cardiac cells are not responsible for male sexual development so SRY gene will be silenced. Thus, gonadal cells will be euchromatin and has low level of DNA methlation summary: if we want more gene expression, less methylation correct answer is B

parathyroid hormone

increases blood calcium levels by increase osteoclast activity - more bone resorption

Transduction

involves DNA transfer from one bacterial cell to another by a bacteriophage (a virus that infects bacteria)

Western blot

laboratory technique that first separates proteins by size (gel electrophoresis) and then transfers them to a blotting membrane - band intensity (thickness) = level of expression of the targeted protein - protein with the shortest (lightest) amino acid sequences have lowest molecular weight -> will migrate quickly and travel far - protein with large concentration -> will have intense band travel distance = how heavy the protein intensity of the band = concentration of protein

clotting factors are form in which organ

liver

Northern Blot

mRNA expression

In a neuron, mitochondrial biogenesis is believed to occur primarily in the cell body, but mitochondria are often positioned at the presynaptic terminal, a distal site with high metabolic demand. Given this information, which molecular mechanism is most likely responsible for mitochondrial transport from the cell body to the presynaptic terminal? A. Kinesin motors transport mitochondria along microtubules B. Kinesin motors transport mitochondria along microfilaments C. Dynein motors transport mitochondria along microfilaments D. Dynein motors transport mitochondria along microtubules

microtubules - composed by tubulin subunits - serving as tracks for intracellular transport of organelles and vesicles -> the movement is maintained by 2 motor proteins: 1. kinesin: anterograde axonal transport (ie, away from the nucleus and toward distal sites) 2. dynesin: retrograde axonal transport of intracellular cargo (ie, from distal sites toward the nucleus) B and C are wrong - Movement along actin microfilaments occur via myosin motors (not kinesin or dynein). - The primary functions of myosin movement along microfilaments are cellular locomotion, cellular division, and muscle contractions correct answer is A

sarcoplasmic reticulum (SR)

muscle fiber organelle that tightly regulates intracellular calcium (Ca2+) concentration. The release of calcium from the SR promotes muscle fiber contraction whereas the transport of calcium into the SR promotes and maintains muscle fiber relaxation. - during relaxation, Ca ions are sequester, and during contraction, Ca ions are Ca ions are released

genetic drift

natural variations in allele frequencies of a population due to random genetic changes that are not related to natural selection (eg, sampling error, chance event). - effect are more significant in small population d/t reduced size gene pool - it increases the probability of allele being fixed in the population

Researchers are studying the last two phases of mitosis, anaphase and telophase, in actively dividing cancer cells. Different fluorescent probes are used to label various cellular components in these cells. Under the microscope, fluorescently labeled DNA appears blue, the nuclear envelope appears green, and the mitotic spindle appears red. Given this, green fluorescence would be most intense during: A.anaphase only B.telophase only. C.both anaphase and telophase. D.neither anaphase nor telophase.

nuclear envelope reform during telophase, so green envelope will be intense in telophase mitosis: prophase -> metaphse -> anaphase -> telephase correct answer is B

what hormones do posterior pituitary secrete

oxytocin and vasopressin - they are direct hormone that act on target directly

what hormones do pancreas secrete and their function

pancreas secrete insulin and glucagon to regulate blood glucose level - insulin: convert glucose to glycogen in liver while glucose level is high - glucagon: stimulate gluconeogenesis and break down of glycogen while glucose level is low

The diagram below shows the results of a northern blot analysis that tested for the expression of four peptide hormones in two endocrine tissues. *** diagram on #2 in word document The endocrine glands that most likely correspond to tissues A and B are the: A.pituitary gland and pancreas, respectively. B.pancreas and pituitary gland, respectively C.adrenal glands and hypothalamus, respectively. D.hypothalamus and adrenal glands, respectively.

pancreas secrete insulin and glucagon to regulate blood glucose level -> tissue A on Northern blot Anterior pituitary secrete GH, TSH, LH, FSH, ACTH, prolactin (posterior pituitary secretes oxytocin and vasopressin) -> tissue B on Northern blot correct answer is B

Viroids

pathogenic, circular, single-stranded RNA molecules lacking protein coats and primarily affect plants. They typically silence the expression of specific genes and inhibit protein synthesis by binding RNA sequences. Viroids enter cells by hiding inside viruses or through damaged tissue; they do not use the mechanisms described in the question.

cell wall

plant: cellulose (plolysaccharides) bacteria cell (prokaryote): peptidoglycan archaea (prokaryote) and animal cell: no cell wall

Transcription factors

proteins that can alter gene expression by binding DNA near gene promoter regions to either increase or decrease the transcription of a target gene. - have nuclear localization sequences that facilitate their entry into the nucleus, where they regulate the expression of target genes.

Telomeres

regions of repetitive nucleotide sequences at the ends of eukaryotic chromosomes that shorten with each round of cell division - protect these ends from deteriorating - does not present in prokaryotes

Positive-sense ssRNA viruses

replicate their genomes by encoding their own viral RNA-dependent RNA polymerase.

Growth Hormone

secreted by the anterior lobe of the pituitary gland; stimulates growth of bones and soft tissues - increase osteoblast activity to increase bone matrix deposition

Which of the following mRNA strands contains the longest open reading frame? A.5′-CCACGAUGCGUUGAGCGC-3′ B.5′-CAAUGGUAAAGUCUUAGU-3′ C.5′-GACGAUGUAACUUGCACU-3′ D.5′-AGAAUGGUAUCCUGAGCC-3′

start codon: AUG stop codon: UAA, UAG, UGA open reading frame is portion of a reading frame that can be translated by ribosomes because it contains both a start codon (AUG) and a stop codon (UAA, UAG, or UGA) within the same reading frame. choice A: 3 nucleotides bwt stop and start => 3 codons choice B: 9 nucleotides => 5 codons choice C: 0 nucleotides => 2 codons choice D: 6 nucleotides => 4 codons correct answer is B

the wobble 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

Glucocorticoids

stimulate the synthesis of glucose from other molecules (ie, gluconeogenesis) and the breakdown of fats into fatty acids (ie, lipolysis). -> stimulate energy in cells

loop of Henle

the active transport of NaCl from the ascending limb maintains the high salt concentration in the kidney's medulla, facilitating the reabsorption of water from the descending limb. - longer loop of henle extending down to medulla enhance water reabsoprtion

Fibrous cartilage

very tough form of cartilage found in the intervertebral disks of the spine and at the junctions where tendons attach to bone - Limits movement - Resists compression forces & stretch - Prevents direct contact between bones (eg, between vertebrae of the spine)

DNA sequencing

the process of determining the precise order of nucleotides within a DNA molecule

Adaptive radiation

the process of diversifying characteristics (eg, claw and teeth size) to better fill an ecological niche. - can lead to speciation

Electrical synapses

transfer information from one cell to another via passive ionic current flow through gap junctions ( cluster of channels that connects the cytoplasms of adjacent cells) - b/c the gap junction, the current past instantaneously from one neuron to the other - signal flow bidirectionary across synapse

chemical synapses

use neurotransmitters to transfer information, which is a slower process. - information transfer is unidirectional

double-stranded DNA viruses

utilize host machinery and resources to transcribe positive-sense mRNA from viral DNA

Based on the sequence that telomerase adds to the ends of chromosomes, the template portion of TR most likely contains which of the following sequences? * from the passage: Using a portion of TR as a template, telomerase extends telomeres by continuously adding the sequence 5′-TTAGGG-3′ to the ends of chromosomes. A.5′-UUAGGG-3′ B.3′-AAUCCC-5′ C.5′-CCCTAA-3′ D.3′-CCCUAA-5′

we need to find the template sequence for 5'-TTAGGG-3' correct answer is B