midterm question answers

midterm question answers - MCDB 100 Midterm...

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MCDB 100 Midterm Questions/Answers Winter Quarter Oct 4, 2007 O’Lague 1. What are two major pieces of molecular evidence that we all evolved from a common ancestor? Ans: We all use DNA and a universal triplet code. 2. What are the major differences between prokaryotic and eukaryotic cells? Ans: haploid circular DNA vs. diploid linear DNA, nucleus, organelles, cytoskeleton. 3. In an EM picture of a part of a eukaryotic cell, name the major structures. Ans: locate nucleus, Golgi, ER, mitochondria, cell membrane, lysosomes, peroxisomes, smooth ER. 4. What are the advantages, if any, in being multicellular? Ans: Cells can specialize by food storage and cell movement and cells feed each other in a complementary fashion. 5. What are three major functions of the cytoskeleton? Ans: cell movement, cell shape, and transport of molecules and organelles within cells. 6. What is the origin of mitochondria? Ans: Probably an Archaea bacteria eating a eubacteria. 7. Why are yeast model organisms for molecular studies? Ans: primitive and simplest Eukaryote with a haploid genome. 8. The majority of Chinese hamster ovary (CHO) cells grown in tissue culture in the presence of methotraxate die, a few survive that grow in its presence. What biological principle(s) is involved in this behavior? Ans: natural selection through the appearance of drug resistance maybe due to spontaneous mutation, but other explanations are possible like overexpression of pre-existing drug resistance in a minority of CHO cells. 9. What are the three major divisions of life? Ans: Archaea, Eubacteria, and Eukarytoa. 10. The amount of an organism chromosomal DNA increases with organism’s complexity? True or False? Explain. Ans: False, probably. Lowly organisms on an evolutionary scale have abundant amounts of DNA compared to more complex organisms.
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11. What is a covalent bond, ionic bond, polar bond, H-bond? Ans: Atoms share electrons, atoms donate and accept electrons, electron spends one time next to the more electronegative atom, and H bonds involve H atom or atoms. 12. Calculate the energy in kcal/mole of red light wavelength is 700nm. What type of bond energy is this equivalent to? Ans: Energy red light = N 0 h ν = N 0 h c/ λ , - Avogadro’s no., h = Planck’s constant, c = speed of light, λ = wavelength, so E = 56.7Kcal/mole. Covalent bond. 13. Condensation reactions in cells are involved in anabolism such as the polymerization of amino acids into proteins. Such reactions should not take place in the aqueous cytoplasm. Why? Ans: Condensation reactions give off water as a product. Water at 55M or so drives these types of reactions backwards. 14. Tertiary and quaternary structures of enzymes in eukaryotic cells are held together by weak, rather than covalent, bonds. Why? Ans: Most enzymes are regulated and must change shape or lose or gain subunits.
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midterm question answers - MCDB 100 Midterm...

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