BSCI330 REVIEW EXAM 1Cells and virusesDynamics of BiomembranesList four different classes of eukaryotic cells.- Plant- Animal- Protists- Fungi What are some of the common features of eukaryotic cells? What about prokaryotic cells?- Eukaryotico Plasma membraneo Cytoplasmo Chromatino Membrane bound organelleso Multiple linear chromosomes with histoneso Nucleuso Nuclear envelopeo Larger in size- Prokaryotico Single circular chromosomes, no histoneso No nucleuso Smaller in sizeo CytoplasmDescribe the structure and composition of a retrovirus virus.- RNA-containing virus that replicates in a cell by first making an RNA-DNA intermediate and then a double stranded DNA molecule that becomes integrated into the cell’s DNA- The term retrovirus refers to the virus’ ability to reverse the usual flow of genetic info, which normally is from DNA to RNA- GP 120 coat protein- RNA- Reverse transcriptase- Capsid - Envelope- Lipid bilayer- Contain 2 RNA molecules- Glycoproteins- Assembled with structural proteinOutline the replication cycle of HIV1. Fusion of HIV to host cell by CD4 and CCR5 (service proteins that the virus recognizes and binds to before entering the cell)2. HIV RNA, reverse transcriptase, integrase, and other viral proteins enter the host cell3. Viral DNA is formed by reverse transcription.4. Viral DNA is transported across the nuclear envelope and integrates into the host DNA by integrase5. New RNA is used as genomic RNA to make viral proteins.6. New RNA and proteins move to cell surface and a new, immature, HIV virus forms.7. The virus matures by protease releasing individual HIV proteins.What are the major protein products encoded by the HIV genome and what are the functions of the proteins in the life cycle of the virus?- GAG- matrix capsid, nucleocapsid- POL- cleaved into 4 parts: protease, integrase, polymerase, reverse transcriptase, RNAase- ENV- cleaved into 2 parts that become part of the envelopeWith one sentence, indicate the contributions to cell biology by each of the following individuals:- Robert Hooke- 1663 focused light on an object, looked at a cork under a microscope, saw cells, and distinguished and named cells for the first time, helpedin plant cell wall- Anton Van Leeuwenhoek- created small microscope and observed lake water (discovered organisms in it), red blood cells, sperm, insects- Peyton Rous- found fibrosarcoma- Irving Langmuir- theorized that oils consisting of an aliphatic chain with a hydrophilic end group (perhaps an alcohol or acid) were oriented as a film one molecule thick (monolayer of oil) upon the surface of water, with the hydrophilic group down in the water and the hydrophobic chains clumped together on the surface. The thickness of the film could be easily determined from the known volume and area of the oil, as area becomes smaller, layer will exert pressure- Gorter and Grendel- the "founding fathers" of our current model of plasma membrane structure, predicted that if a plasma membrane were really a bilayer then its surface area should be half that occupied by all its amphipathic lipids spread out in a monolayero Hydrocarbon tails= 30Ao Polar ends= 15A- Davson and Danielli- The fluid mosaic model expanded on the Davson–Danielli model by including transmembrane proteins, and eliminated the previously-proposed flanking protein layers that were not well-supported by experimental evidence.- Singer and Nicolson- 1972, how proteins are positioned in membranes, lipid bilayer structures fluid mosaic model- Linus Pauling- found the alpha helical structureWhat is meant by a unit membrane? Give an illustration for how the membrane would look under the electron microscope. What about under the light microscope?- Approx. 60-80 angstrum (A) which is equivalent to 6-8 x 10 ^ -10 meters- All have a rail road like structure- All membranes have itWhat are the major constituents of biological membranes of eukaryotic cells?- Proteins50%- Carbohydrates10%- Lipids (mostly phospholipids=fatty acid, phosphate group, gylcerol)40%Give the structure and name of a saturated fatty acid. Show the structure of the fatty acid when it is unsaturated.cis double bond in center of unsaturated, causing it to kinkjust a carboxillic acid and a fatty acid chainWhat are the constituents of a phospholipid? Draw the structure and label the constituentsof a phospholipid.- Fatty acids, phosphate group, glycerol (kinks), R groupDefine each of the following terms- Amphipathic- contains both hydrophilic and hydrophobic- Hydrophobic- inside of a lipid bilayer, doesn’t like water, nonpolar- Hydrophilic- outer part of a lipid bilayer, likes water, polarDraw the structure of cholesterol and indicate why the molecule is amphipathic- Amphipathic because it has a polar head, steroid rings, and non polar hydrocarbonHow do we know that the plasma membranes of red blood cells consist of a bilayer of phospholipids? Briefly outline the history behind this conclusion (and/or how you would design an assay to confirm the conclusion).o Gortel and Grendel 1925- used acetone to extract lipids from RBCs. Knew surface area of RBCs. Placed extract on trough and measures monolayer surface area. Cell surface area showed double of monolayer demonstrating bilayer structureProvide a diagram and a brief description of the fluid mosaic model of the structure of biological membranes. What was the experimental basis for the original proposal?- The plasma membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. - The membrane is depicted as mosaic because like a mosaic that is made up of many different parts the plasma membrane is composed of different kinds of macromolecules, such as integral proteins, peripheral proteins, glycoproteins, phospholipids, glycolipids, and in some cases cholesterol, lipoproteins.- plasma membrane is a lipid bilayer (interspersed with proteins). It is so because ofits phospholipid component that can fold in itself creating a double layer - orbilayer - when placed in a polar surrounding, like water.- Original basis- the standard model for membrane structure, the Davson-Danielli-Roberston (DDR) model, was a bilayer of lipids between two monolayers of unfolded protein. Each protein layer faced an aqueous environment, cytoplasm or interstitial fluid, depending upon whether the membrane enclosed an organelle or the cell itself.o Singer and Nicholson
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