BIOLOGY - MCAT

Self assembly of phospholipids

-Will self-assemble in the aqueous environment of the human body - Micelles- Liposomes- Plasma and organelle membranes

Viral pathway

1.) Virus enters via endocytosis 2.) Virus uncoated in phagolysosome 3.) Viral genomes replicate in the host nucleus 4.) Viral protein synthesis in ER and cytosol 5.) Viral glycoproteins trafficked to membrane 6.) Viral capsid is assembled 7.) Viral envelope acquired by budding - enveloped viruses acquire this while exiting the host cell

connective tissue

A body tissue that provides support for the body and connects all of its parts Support the body, and provide a framework for epithelial cells--In most cells, they form the stroma or support structures by secreting materials to form an extracellular matrix Osteoblasts and clasts Bone, cartilage, tendons, ligaments, adipose tissue, and blood are all connective tissues.

phospholipid bilayer

A double layer of phospholipids that makes up plasma and organelle membranes. Head is negatively charged - exterior tail is neutral/nonpolar/hydrophobic- on the interior inner leaflet head groups are the phospholipid components facing the cytosol- protons contribute positive charges to molecules- therefore when more functional grouops in a phospholipid head are deprotonated than protonated, the head group carries an overall negative charge and attracts positive molecules, facilitating binding

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement. functions to give the cell its shape, support cellular motility, and help organize intracellular components Three components of the Cytoskeleton: microfilaments (actin filaments), microtubules, and intermediate filaments

endomembrane system

A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles. The endomembrane system is the portion of the cells that is in charge of modifying proteins that will be secreted. Thus, it is most likely that insulin cleavage will occur in the endomembrane system. Nuclear envelope, endoplasmic reticulum, Golgi apparatus, vesicles, lysosomes, and vacuoles

motor proteins

A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell. myosin - a motor protein binds to actin to move around the cell myosin Va is a motor protein. Motor proteins such as myosin Va move along microfilaments through interaction with actin.

peptidoglycan

A protein-carbohydrate compound that makes the cell walls of bacteria rigid

cellulose

A substance (made of sugars) that is common in the cell walls of many organisms - primary component of the cell wall in plant cells - is not found in the membranes of animal cells

Bacteriophage

A virus that infects bacteria excusively infect bacteria but do not enter host cells to replicate their genetic matieral - instead they use their tail sheath - a structure that injects the phage genome into a bacterium - the remaining viral structures of the phage, such as the tail fibers, the capsidm and the tail sheath, ar eleft outisde the bacterium

Enveloped Viruses

All viruses contain a protective protein called the capsid - composed of individual capsomere subunits - viruses that have an additional phospholipid bilayer surrounding the capsid are considered enveloped viruses - this helps the virus evade the immune system and contain enveloped proteins required for cellular entry Enveloped viruses are more sensitive to heat, detergents, and changes in moisture that disrupt the lipid bilayer - more susceptible to changes in environmental conditions non-enveloped or naked viruses have only a capsid as a protective outer layer - more resistant to heat, detergents, and changes in moisture viruses with a capsid encased in a phospholipid membrane, known as enveloped viruses, can fuse their membranes with the cell membrane - no vesicle is formed, and the capsid is released directly into the cytosol

Plasma membrane (eukaryotes)

Amphipathic phospholipids that have a polar head and a non-polar tail- bilayer membrane- polar head face the intracellular and extracellular (aqueous) environments and the non-polar tails remain inside the membrane. mostly phospholipid with proteins and cholesterol The presence of cholesterol and lipid rafts within the plasma membrane help contribute to the fluidity of the membrane at lower temperatures and to its stability at higher temperatures. can add fluidity at low temperatures - allows the cell membrane to be stable at high temps The bilayer is permeable to very small uncharged molecules and to lipid-soluble molecules- which can freely diffuse through the cell membrane. The membrane is not permeable to larger, hydrophilic molecules such as glucose. Phospholipids are involved in cell signaling, second messengers Second messengers are small molecules and ions that relay signals received by cell-surface receptors to effector proteins.

Endoplasmic Reticulum (ER)

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions. Rough ER- protein formation/translation - ribosomes Smooth ER - Lipid synthesis- and the detoxification of certain drugs and poisons. - include cholesterol and cholesterol derived-molecules (steroid hormones) Is located near the nucleus and is present in all human cells except red blood cells and spermatozoa

Prokaryotes

Archaea and Bacteria- Archaea - extremophiles- live in harsh environments Bacteria - have many similar structures to eukaryotes Spherical-cocci, rod-shaped - bacilli, and spiral-shaped - spirilla - morphology Carry out the electron-transport chain using the cell membrane. ~ 1-5 um - micrometers DNA: Single circular chromosome, double-stranded, single Origin of Replication, Haploid, No telomeres, Located in cytoplasm Cellular respiration in cytoplasm aerobic and anaerobic - glycolysis occurs in the cytoplasm of both prokaryotic and eukaryotic cells - results in the synthesis of pyruvate Cell wall contains peptidoglycan in bacteria Prokaryotic ribosomes are smaller than eukaryotic ribosomes (30s and 50s) rather than 40S and 60S All prokaryotic cells contain ribosomes Binary fission lacks membrane-bound organelles such as the Golgi body and the smooth endoplasmic reticulum present in eukaryotes

Defects in biological pathways

Are likely to affect all cell types, tissues, and organs in which those pathways are involved

Three domains of life

Bacteria, Archaea, Eukarya

F+ cell

Bacterial cells that possess a plasmid called the F factor, which includes a gene for a sex pilus.

Pinocytosis

Cell drinking - nonspecific process (does not require receptor binding) that involves the continuous invagination of the cell membrane to take up extracellular fluid

Phagocytosis

Cell eating - when cells engulf external particles by extending portions of their membrane to reach around the particle rather than by the inward budding of the membrane

membrane lipid

Cholesterol stabolizes the membrane fluidity by both decreasing fluidity at higher temperatures and increasing fluidity at lower temepratures Able to accomplish this because its hydrophobic portion is made of four fused rings - this structure restricts the rotation of the bonds involved, imparting rigidity and decreasing fluidity at high temperatures It also impairs packing of the fatty acyl tails of the phospholipid component of the membrane, increasing fluidity at low temperatures esterification of cholesterol would replace the hydrophilic hydroxyl group with a much less polar ester bond connected to a large acyl group - this modification reduces the ability of cholesteryl esters to interact with water and destabilizes the localization of cholesteryl esters on the exterior-facing surface of membranes Hydrophobic interactions push the added acyl tail to the interior side of the phospohlipid monolayer, and the overall nonpolar chelesterl ester diffuses from the surface to the core of the lipoprotein particle

Golgi apparatus

Consists of stacked membrane bound sacs- packages and modifies

Retroviruses

Contain a single-stranded RNA genome, from which a complementary DNA strand is made using reverse transcriptase. The DNA strand can be integrated into the host cell genome, replicated, and transcribed as if it were the host cell's DNA. HIV is a retrovirus that utilizes this life cycle, which is why it is difficult to treat Like other retroviruses, HIV contains reverse transcriptase, an enzyme that converts the viral genome from RNA to DNA Are enveloped, positive-sense, single-stranded RNA viruses that convert their RNA genomes into double-stranded DNA using the enzyme enter the host cell through endocytosis - allowing the capsid and envelope to uncoat (disassemble). Uncoating releases the viral genetic material inside the host cell then convert their genomes from positive ssRNA into dsDNA - before integration into the host genome can occur using reverse transcriptase (RNA-dependent DNA polymerase) Once the dsDNA has been integrated the viral genome is replicated along with the host cells' own DNA as a lysogenic provirus dsDNA is integrated into the hosts DNA genome - not ssRNA

Peroxisomes

Contain hydrogen peroxide, one of the main functions is the breakdown of very long chain fatty acids via B-oxidation Participate in the synthesis of phospholipids and contain some of the enxymes involved in the PPP contain various oxidoreductase enzymes and function to help maintain the proper oxidation states within cells

Nucleus

Contains all the genetic mateoral necessary for replication of the cell. It is surrounded by the nuclear membrane or envelope, which is a double membrane that maintains a nuclear environment seperate and distinct from the cytoplasm. Nucler pores in the nuclear membrne allow selective two-way exchange of material between the cytoplasm and the nucleus. DNA contains coding regions - genes. Linear DNA is wound around organizing proteins known as histones, and is then further wound into linear strands called chromosomes Nucleolus - where ribosomal RNA - rRNA is produced- makes up about 25% of the nucleus

Epithelial tissue

Cover the body and line cavities, protecting against pathogen invasion and desiccation. Some epithelial cells absorb or secrete substances, or participate in sensation In most organs, they form the parenchyma or the functional part of the organ Cover the ovaries Can be classified by the number of layers Simple - 1 Stratified - many layers Pseudostratified - multiple layers due to differences in cell height but actually have only one layer epithelial cells are specialized cells for secretion and are present in the respiratory tract. secrete mucous are packed together tightly into sheets that make up the outer layer of the skin (the epidermis), the secretory cmponents of glands, and the lining of the inner cavities of the body (the lumen of hollow organs such as the GI tract) comprise the sin and the linings of the organs, so they udnergo rapid cell divisions in order to replace the damaged cells Lines surfaces, protection, absorption, filtration, and secretion Skin - lining of hllow organs (digestive tract, and trachea)

solubility of phospholipids

Depends on both the hydrophobic and hydrophilic regions of the molecule - charged head groups are more soluble than neutral groups because they more readily form hydrogen bonds wheras lipids with long hydrophobic chains have decreased solubility can be separated by thin-layer chromatography

Differentiating phospholipids

Each phospholipid has a unique mass,charge, and solubility due to distinct features in the backbone, poalr head groups, and fatty acid chains - they may be separated based on each of the following properties Composition of the head groups and the length of the tails create lipids with distinct charge,mass, and solubility

Endosomal pathway

Endocytosis -> Vesicle -> Early Endosome -> Late endosome -> Lysosome

endonuclease vs exonuclease

Endonuclease cleaves Phosphodiester bonds within the polymer, exonuclease cleaves phosphodiester bonds at the ends of the polymer

Yeast is.....

Eukaryotic - so multiple origins of repiclations

Centrioles

Found in a region of the cell called the centrosome, they are the organizing centers for microtubules and are structured as nine triplets of microtubules with a hollow center.

positive sense ssRNA virus

Genomer can directly serve as an mRNA molecule in the host cytoplasm - can be immediately translated by host ribosomes to frm viral proteins - these viruses heve there own viral RNA-dependent RNA plymerase - don not require host polymerase.

gram positive and gram negative

Gram positive- purple gram stain, and have a thick cell wall composed of peptidoglycan and lipothichoic acid Gram negative- turn pink during a gram stain, have a thin cell wall composed of peptidoglycan and an outer membrane containing phospholipids and lipopolysaccharides

membrane fludity

Is determined by the cocnentration of cholesterol and the tail length of fatty acids

charge on phospholipids

Is determined by the structure of the polar heads - the phosphate component of the head group may be linked to various chemical groups - positively charged groups such as choline or ethanolamine neutralize the negative charge of the phosphate whereas neutral groups such as serine allow the ehad to maintain a net negative charge The charges of phospholipids depend on the head groups attached to the phosphaet. Can be either neutral or negatively charged

Mass of phospholipids

Is established by the molecular weight of the backbone and the polar head groups - backbones can contain either a glycerol with two fatty acid tails or sphingosine with one fatty acid tail Glycerophospholipids tend to be larger than sphingophospholipids because thay have two fatty acid tails instead of one - polar head groups may be as small as a phosphate (phosphatidic acid) or as large as phosphatidylglycerol. They can be separated by size-exclusion chromatography

flagella

Is ocmposed of a basal body, a hook, and a hollow filament filled with flagellin. The hook connects the filament to the basal body, and the basal body serves as the motor that generates motion The compound that generates torque is the basal body, transmembrane unit that works as a molecular motor The hook is a flexible structure that connects the basal body and the filament. It transmits torque generated by the basal body but does not generate any rotation itself The filament responds to rotation and propel bacteria, but do not generate rotational motion - are the recipients of the rotation generated by the basal body

Bacteria movement

May have one, two, or many flagella that generate propulsions to move the abcterium toward food or away form immune cells. Bacterial flagella contain a filament composed of flagellin, a basal body, that anchors and rotates the flagellum, and a hook that connects the two Moving in response to chemical stimuli is called chemotaxis Bacteria respond to chemical stimuli in the extracellular environment by moving away from or toward increasing concentrations of signal molecules. This movement, known as chemotaxis, allows bacteria to adjust the direction of their movement toward target cells and is an important part of infection. Impairing the ability to detect or respond to chemical signals can reduce virulence

Glycolipids

Membrane carbohydrates that are covalently bonded to lipids. Glycolipids are lipids with a carbohydrate attached by a glycosidic (covalent) bond. Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the connections that allow cells to connect to one another to form tissues. Glycolipids are located on the surface of cell membranes and typically do not extend through the entire bilayer. Glycolipids act to provide energy and also serve as markers for cellular recognition. Glycolipids are glycoconjugates of lipids that are generally found on the extracellular face of eukaryotic cellular membranes, and function to maintain stability of the membrane and to facilitate cell-cell interactions.

Glycoproteins

Membrane carbohydrates that are covalently bonded to proteins. Glycoproteins perform vital biochemical and structural functions. They enable cells to recognize another cell as familiar or foreign, which is called cell-cell recognition. They also help cells attach to and bind to other cells, which is called cell adhesion. Glycoproteins are always found on the outside of the plasma membrane, with the sugar facing out. This is an image of the plasma membrane with glycoproteins labeled.

Muscle tissue

Mesoderm Voluntary movement (skeletal muscle) Involuntary movement - (cardiac and smooth muscle) Ex: Skeletal (attached to bone) Cardiac (heart) smooth muscle (hollow organs) Is under the control of the nervous system and allows for movement - although connective tissue comes into contact with muscle tissue, muscle is not considered to be a type of connective tissue

microfilaments and microtubules

Microfilaments - These are made up of solid polymerized rods of action. The actin filaments are organized into bundles and networks that are -resistant to compression and fracture, protecting the cell. It can also use ATP to generate force for movement by interacting with myosin, such as in muscle contraction - made of actin protein subnits organized into double-stranded rods. help determine the overall shape of a cell and assist in some cellular locomotion - also responsible for muscular contractions Also, plays a role in cytokinesis or the division of materials between daughter cells - cleavage furrow during cytokinesis

membrane bound organelles continued

Nucleus: contains DNA and a sub-organelle known as the nucleolus, which is responsible for ribosome assembly.- transcription occurs here in eukaryotic cells Mitochondria- are sometimes known as the powerhouse of the cell; they are self-replicating organelles with their own DNA that are the location of the citric acid cycle and oxidative phosphorylation in eukaryotes- ATP production Ribosomes- themselves are not membrane-bound organelles, and they are not unique to eukaryotes (although prokaryotic ribosomes have a different structure).- play an improtant part in protein translation Golgi apparatus- modifies proteins and packages them into membrane-bound vesicles that are then sent to the ultimate destination of the proteins.

Bacteria classified based on metabolic processes

Obligate earobes - require oxygen for metabolism Obligate anaerobes - cannot survive in oxygen-containing envrionments and can only carry out anaerobic metabolism Facultative anaerobes - can survive in envrioenments with or without oxygen-will toggle between based on the environment Aerotolerant anaerobes- cannot use oxygen for metabolism, but can survive in an oygen-containing environment

secretory pathway

Rough ER -> Golgi -> secretory vesicles -> cell exterior In the RER - some post-traslational modifications may occur - glycosylation,disulfide bond formation, phosphorylation, and protein cleavage Golgi packages proteins destied for the plasma membrane into secretory vesicles - which fuse with the plasma membrane other organelles, such as the nucleus, mitochondria, and eproxisome, are not involved in the secretory patheay

receptor-mediated endocytosis

The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.

Mitochondria

The powerhouse of the cell, organelle that is the site of ATP (energy) production The outer membrane serves as a barrier between the cytosol and the inner environment of the mitochondrion. The inner membrane, which is arranged into numerous infoldings called cristae, contains the molecules and enzymes of the ETC, they are highly convoluted structures that increase the surface area available for ETC enzymes. The space between the inner and outer membrane is called the intermembrane space, the space inside the inner membrane is called the mitochondrial matrix. The pumping of protons from the mitochondrial matrix to the intermembrane space, establishes the proton-motive force; ultimately these protons flow through ATP synthase to generate ATP during oxidative phosphorylation. They are semi-autonomous, contain their own genetic information- circular - self-replicating Can also start apoptosis, from the release of enzymes from the ETC

Exocytosis

The process by which a cell releases large amounts of material Out of cell - requires cellular energy - transports Macromolecules (like proteins) Requires energy like ATP

peripheral proteins

The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane. Peripheral proteins, or peripheral membrane proteins, are a group of biologically active molecules formed from amino acids which interact with the surface of the lipid bilayer of cell membranes. Unlike integral membrane proteins, peripheral proteins do not enter into the hydrophobic space within the cell membrane

Free radicals from ionizing radiation are highly unstable and have carcinogenic effects. These effects most likely result from damage to:

The question stem states that free radicals can cause cancer, which is a result of poorly regulated cell growth and division. Cancer is generally a product of mutations in DNA that disrupt these processes. Therefore, we must choose the answer that targets DNA.

Genetic recombination

The regrouping of genes in an offspring results in a genetic makeup that is different from that of the parents. Bacterial genetic recombination increases bacterial diversity Recombination occurs when genetic material is broken and recombined.

Intermediate filaments

Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments Are involved in cell-cell adhesion and maintenance of the integrity of the cytoskeleton, they help anchor organelles. - keratin and desmin Are composed of several protein types (keratin, lamin) Work with microfilaments to determine cellular shape Make up the nuclear lamina (inner lining of nuclear envelope) Assist in anchoring organeeles to specific comprtments within the cell Provide crucial support for the cell to be able to withstand mechanical forces (compression)

Transformation, conjugation, transduction, and transposons

Transformation - occurs when genetic material from the surroundings is taken up by a cell, which can incorporate this material into its genome- many gram-negative rods can carry this process out - transfers genetic material from the environment into bacteria Conjugation-The transfer of genetic material, plasmids, from,m one bacterium to another across a conjugation bridge- made of sex pili, a plasmid can be transferred from F+ cells to F- cells or a portion of the genome can be transferred from an Hfr cell to a recipient- exchange of nucleic acids between bacteria - direct contact - donor cell contains F (fertility) facto plasmid - circular piece of DNA containing genes that direct the formation of the sex pilus Transduction - The transfer of genetic material from one bacterium to another via a bacteriophage vector - a virus that carries genetic material from one bacterium to another Transposons - genetic elements that can insert or remove themselves from the genome

Archaea

Unicellular Absent: Nucleus, Organelles, cell wall with peptidoglycan Binary fission for cell division Circular Chromosome

RNA viruses

Usually single-stranded, may be double-stranded, may be segmented into separate RNA pieces RNA viruses require a type of transcriptase (reverse transcriptase) to replicate themselves. viruses don't actually alter the host polymerase to translate their RNA, viruses either carry positive sense RNA which can be directly translated by the host enzymes without modification, or negative sense as described above, or double stranded RNA which integrates itself into the host DNA and will wait to create viral progeny (lysogenic vs lytic cycle)

Hfr cell (high frequency of recombination)

a bacterial cell in which the F factor has become integrated into the chromosome

fluidity of cell membranes

affected by several factors, such as temperature and membrane composition - increasing the temperature increases the average kinetic energy of the membrane components - increasing fluidity vice versa with a decrease in temperature under prolonged exposure to an external stimulus that affect fluidity, cells may initiate a homeostatic response to counter this change - such as by changing their membrane composition So, for example: in a colder environment, since fluidity is decreased, to maintain homeostasis, the phospholipid would increase in unsaturated fatty acids - since they have a double bond and more pi bonds - they increase fluidity

LDL cholesterol

bad cholesterol, an increased amount of LDL cholesterol change the composition of the cell membrane, making it more rigid, which can impair the proper formation of trafficking vesicles

endosomes

carry and sort material brought into the cell (endocytosis) the entry of the virus into the host cell requires CatB and CatL proteases and involves endocytosis through the fusion of the viral membrane with the host cell membrane. Endosomes mediate the internalization of viral particles through endocytosis. Endosomes are formed to transport a substance from the outside of the cell, not inside the cell. The endosomal pathway begins at endocytosis where, following the internalization of extracellular materials into vesicles, the vesicles containing these materials mature into early endosomes, late endosomes, and finally lysosomes Some endosomes participate in alternative pathways such as trafficking through the Golgi apparatus - this pathway allows the cargo within the vesicles to enter the secretory pathway and be expelled from the cell by exocytosis (bypassing degradation by the lysosome) Endocytic argo that does not enter alternative pathways (entry into the secretory pathway) and fails to escape from endosomes will end up in the lysosome to be degraded

Virulence plasmids

carry instructions for structures, enzymes, or toxins that enable a bacterium to become pathogenic

Lysosomes

contain hydrolytic enzymes for digestion, and are capable of breaking down many substrates, including substances ingested by endocytosis and cellular waste products. Often function in conjunction with endosomes, which transport package, and sort cell material traveling to and from the membrane when a macrophage ingests foreign material, the material initially becomes trapped in a phagosome. The phagosome then fuses with a lysosome to form a phagolysosome. Inside the phagolysosome, enzymes digest the foreign object. Of the cell structures listed, the labeled carbohydrate is most likely to be microscopically visualized within a lysosome (phagolysosome) serves as the digestive system of the cell - it contains an acidic environment and various hydrolytic enzymes that facilitate the degradation of various biomolecules

nucleoid region of bacterial prokaryotic cells

dsDNA is condensed into a circular chromosome that has no telomeres or associated histones

membrane bound organelles

endoplasmic reticulum-a net-like organelle that extends out from the nuclear membrane. It is divided into the rough ER and the smooth ER. Rough ER- is rough because it is covered with ribosomes, which are the site of protein synthesis Smooth ER- does not have ribosomes, and is involved in lipid metabolism (both synthesis and breakdown), the production of steroid hormones, and detoxification. Lysosomes- are the garbage disposal system of the cell; material from outside the cell enters the lysosomes through endocytosis, while material from inside the cells enters through autophagy. They contain hydrolases that operate best at acidic pH levels, and the lysosomes are therefore kept at a pH of 4.5-5.0.- contain degradative enzymes Peroxisomes- play a major role in the metabolism of very-long-chain lipids by breaking them down to medium-chain lipids that are transported to the mitochondria for further processing and play a role in detoxification of substances such as ethanol.

Protease

enzyme that digests protein into smaller fragments

Phosphatidyl -

ethanolamine, choline - are neutrally charged serine, and inositol are all negatively charged phospholipids Same as Diphosphatidylglycerol

Disease causing pathogens

eukaryotic cells, prokaryotic cells, or viruses

glycerophospholipids vs triglycerides

glycerophospholipids have two fatty acid chainds and a phosphate group - triglyceride has 3 fatty acids and a glycerol group

Desmin

intermediate filament of muscle cells, forming the scaffold on which actin and myosin contract

Bacterial growth phases

lag - The bacteria adapt to new local conditions log- or exponential phase- growth then increases exponentially stationary,- As resources are reduced, growth levels are off death - As resources are depleted, bacteria undergo a death phase

Sphingolipids

long fatty acid chain polar head group backbone=amino alcohol (not glycerol) short unsaturated fatty acid tails increase membrane fluidity by preventing phospholipids fro clustering together, but longer saturated tails such as those typically found in sphingolipids induce lipid clustering and decrease fluidity

plasma membrane prokaryotes

mainly made of lipids and proteins. controls the movement of substances into and out of the cell E. coli membranes are roughly 75% protein and 25% phospholipid, by mass.

vaccines

mimic antigens - distinct parts of the disease - to allow the ummune system to ready a response in case of lter infection HIV's high mutation and proliferation rates mans that large numbers of highly variable forms of the disease attack the body the best target to creat a vaccine for HIV would be gp120 - an excellent candidate due to its relative strucutral stability, and because it is located on the outside of the virus, which is a lot easier for the vaccine to target

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane Composed largely of phopholipids Said to be fluid as its various non-phospohlipid components can migrate laterally (side to side) through the entire phospholipid-rich surface of the cell in any direction Other important comonents include cholesterol, glycoproteinsl, and glycolopids transmembrane proteins are other components that can move laterally

scaffold proteins

organize groups of intracellular signaling molecules into signaling complexes In biology, scaffold proteins are crucial regulators of many key signalling pathways. Although scaffolds are not strictly defined in function, they are known to interact and/or bind with multiple members of a signalling pathway, tethering them into complexes. In such pathways, they regulate signal transduction and help localize pathway components (organized in complexes) to specific areas of the cell such as the plasma membrane, the cytoplasm, the nucleus, the Golgi, endosomes, and the mitochondria.

integral proteins

penetrate the hydrophobic interior of the lipid bilayer trafficking or membrane transport is likely mediated by components that go through the entire membrane integral proteins affect membrane transport/trafficking and they are a membrane component that pass all the way through the cell membrane

Glycerophospholipids (phosphoglycerides)

phospholipids that contain a glycerol backbone bonded by ester linkages to two fatty acids and by a phosphodiester linkage to a highly polar head group most common type of phospholipid each of the bonds to the glycerol backbone can undergo hydrolysis, which breaks the bond as water is added - when all bonds are broken, glycerol is released, along with two fatty acids and the phosphate headgroup the initial concentration of glycerophospholipids was 20mM because one glycerol molecule is released per glycerophospholipid, the final concentration of glycerol approaches 20mM as the reaction proceeds because two fatty acids are initially attached to each glycerol molecule, the final concentration of fatty acids (40 mM) is twice that of glycerol

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane Surroundings are enveloped by a portion of the cell membrane - the portion subsequently pinches off from the rest of the membrane and becomes a vesicle inside the cell The vesicle then matures and merges with other membrane-bound compartments to become an endosome Cells can conduct endocytosis through three majore mechanisms; phagocytosis, pinocytosis, and receptor-mediated endocytosis

Proteosome

protein complexes that destroy the proteins bound to ubiquitin to get rid of deformed or proteins no longer needed Proteins are tagged for degradation in a process known as ubiquitination - causes the proteosome to recognize and degrade the marked protein via proteolysis 9peptide bond cleavage) System is responsible for degrading damaged or unnecessary protein/enzyme

tubulin

protein that makes up microtubules, has polarity a cytoskeletal protein

F- cell

recipient cell

Lipid rafts

regions of relatively high order (low entropy)- help localize distincy processes or pathways to specfic regions of the membrane by recruiting the proteins and other components involved and holding them in proximity to each other (rather than being allowed to drift freely) To maintain a more ordered state, lipid rafts tend to be rich in sterols (cholesterol in animals and similair molecules called phytosterols in plants) and are relatively poor in phospohlipids compared to other regions of the membrane High temperatures - provides rgidity and stabilizes the membrane Lowe temepratures - increase membrane dluifity by preventing phospohlipids from clustering together

viral progeny

released through cell death, lysis, or extrusion

Lysosomal storage disorders

result from the absence of specific lysosomal enzymes thus allowing undigested material to accumulate

transposons

segments of DNA that can move from one region of DNA to another

Autolysis

self-destruction of cells; decomposition of all tissues by enzymes of their formation without microbial assistance

Plasmids

small circular DNA molecules that replicate separately from the bacterial chromosome Extrachromosomal material can be carried on this may contain antibiotic-resistance genes or virulence factors plasmids that can integrate into the genome are called episomes

Viral Genome

ssDNA-Positive sense-genome may be directly translated by ribosomes of host Negative sense-RNA replicase-complementary strand needs to be made before translated

quorom sensing in bacteria

the regulation of gene expression in response to fluctuations in cell-population density\ CHanges in gene expressiona re dependent on the cellular density of bacteria that rpoduce and secrete the auto induve, a signaling molecule that influences the activity of specific genes in nearby cells

Viruses

tiny particles, smaller than bacteria and other pathogens, which must invade living cells in order to reproduce; when they invade, the cells are damaged or destroyed in the process releasing new particles to infect other cells Contain genetic material, a protein coat (capsid) and sometimes a lipid-containing envelope - are obligate intracellular parasites, that can't survive and replicate outside of a host cell, indivudal virus particles = virions Bacteriophages- viruses that target bacteria Viral genomes- may be composed of DNA or RNA, and may be single-or double-stranded Single - may be positive sense(that can be translated by the host cell) or negative sense - which requires a complementary strand to be synthesized by RNA replicase before translation A virus that requires transport to the nucleus in order to produce viral proteins likely requires use of nuclear RNA polymerase, therefore only DNA viruses need to be transported to the nucleus to produce viral proteins All viruses are obligate intracellular parasites because they cannot replicate independently outside of a host cell.

micelles

tiny spherical complexes of emulsified fat that arise during digestion; most contain bile salts and the products of lipid digestion, including fatty acids, monoglycerides, and cholesterol

Bacteriophage vectors

useful viral vectors for replicating large DNA fragments