BSCI330 REVIEW QUESTIONS SET 1 List 4 different classes of eukaryotic cells animal plant fungi protist Common features of eukaryotic cells nucleus nuclear envelope chromatin multiple linear chromosomes with histones membrane bound organelles cell division by mitosis or meiosis larger in size cytoplasm plasma membrane different types of organelles Common features of prokaryotic cells single circular chromosome no histones no nucleus smaller in size cytoplasm Structure and Composition of retrovirus Definition a retrovirus is an 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 a cell s DNA gp 120 coat protein contains 2 RNA enveloped in lipid bilayer reverse transcriptase glycoproteins assembled with structural proteins Outline the replication cycle of HIV 1 Fusion of HIV to host cell by CD4 and CCR5 co receptor proteins 2 HIV RNA reverse transcriptase integrase and other viral proteins enter the host cell 3 Viral polymerase makes RNA DNA by the enzyme reverse transcription 4 Viral DNA binds to integrase and integrase brings DNA across nuclear envelope and inserts DNA into chromosome DNA of host cell 5 New viral RNA is used as genomic RNA and to make viral proteins 6 New viral 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 gp120 an HIV glycoprotein that protrudes from the outer surface of the virion binds to a CD4 receptor on a T cell to facilitate entry of viral nucleic acid and proteins into the cell GAG all structural to help make it fold matrix lines envelope capsid protects core nuclear capsid protects genome POL integrase integrates DNA into chromosome of host cell protease cleavage of GAG protein to help virus maturation viral polymerase reverse transcriptase RNA DNA RNase degrades RNA ENV cleaved into 2 pieces that become part of viral envelope Individual contributions to cell biology Robert Hooke looked at cork under microscope and found celluli and separately found mucoi a type of fungus Anton Van Leeuwenhoek created a small microscope observed lake water red blood cells sperm and Peyton Rous injected fibrosarcoma into healthy chickens viruses genome was RNA which encoded insects In lake water he found microorganisms into host DNA and caused cancer two RNA molecule enveloped in lipid bilayer Irving Langmuir studied films with monolayer of oil and found that hydrophobic ends stick together area decrease pressure increase Gorter and Grendel surface area of lipid bilayer hydrocarbon tails are 30 angstrom and polar ends are Davson and Danielli there model of cell membrane had lipid bilayer with a layer of protein coating on 15 angstrom top and bottom Singer and Nicolson fluid mosaic model integral proteins embedded into lipid bilayer and peripheral proteins Linus Pauling found alpha helix structure of proteins Unit Membrane 60 80 angstrom 6 8 x 10 10 m all have a railroad like structure concluded that all membranes must have same underlying structures What are the major constituents of biological membranes of eukaryotic cells 50 proteins 40 lipids mostly phospholipids made of fatty acids phosphate groups and glycerols 10 carbohydrates Saturated fatty acid Unsaturated fatty acid KNOW STRUCTURES CHART What are the constituents of a phospholipid fatty acids phosphate group glycerol Define the following terms amphipathic has hydrophobic and hydrophilic constituents hydrophobic non polar doesn t go near water hydrophilic polar goes near water Draw structure of cholesterol amphipathic because it has polar hydrophilic and non polar hydrophobic end How 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 RBC don t have a nucleus or membrane bound organelles so any lipids found would have to be in the plasma membrane extract lipids with acetone used Langmuir trough to determine area lipids could cover could measure surface area of RBC so they could calculate total surface area covered by membrane lipid extracted could cover twice the area needed to enclose cells so double layer of lipids Fluid Mosaic Model Singer and Nicolson developed this model because they didn t agree with the original model from Davison and Danielli which stated that there was a protein coat on outside of lipid bilayer Outline the freeze fracture freeze etch method used to examine structure of biomembranes and contrast this with older EM method of examining membranes in sections stained with osmium tetraoxide Freeze fracture freeze fracture vacuum sublimate platinum carbon replicate of exposed surface is made dissolve cells EM in liquid nitrogen cells freeze but if you bring the temperature up slowly then not all cells will die more cell preservation more ragged surface when sliced Osmium tetraoxide stain tissue add aldehyde which causes tissues to create bonds add OsO4 osmium tetraoxide stain embed tissues in plastic like epoxy resin slice in thin sections bombard with electrons flourescent screen under microscope glows when hit with electrons Describe the various ways by which proteins are anchored to biological membranes and what is meant by peripheral membrane proteins versus integral membrane proteins proteins bind to lipid bilayer by covalently linked fatty acids proteins on plasma membrane are glycosylated Peripheral membrane proteins penetrate into the membrane Integral membrane proteins side chains transmembrane segment contains amino acids with hydrophobic associated with molecules on membrane surface but do not How are proteins anchored to a membrane via a fatty acid Show the orientation of the fatty acid and the rest of the protein in relation to the lipid bilayer protein links to the cytosolic surface of the plasma membrane via covalently attached fatty acid protein binds to membrane via a covalently attached lipid anchor What is meant by a glycoprotein How are the elements of membrane glycoproteins oriented in plasma membranes What about the case of membrane glycolipids proteins that contain oligosaccharide chains covalently attached to polypeptide side chains glycoproteins are in carbohydrate layer of the non
View Full Document
Unlocking...