BIOL 11000 Exam Review: Biomolecules, Cells, Metabolism, DNA and Evolution

Terms in this set (30)

1. Why is water a good solvent and why does ice float?Water is polar and forms hydrogen bonds, so it dissolves ions and polar molecules. Ice forms an open hydrogen-bonded lattice that is less dense than liquid water.
2. Four major classes of biological macromolecules and their monomersCarbohydrates (monosaccharides), proteins (amino acids), nucleic acids (nucleotides) and lipids (not true polymers; fats are built from glycerol and fatty acids).
3. Dehydration synthesis vs hydrolysisDehydration synthesis joins monomers by removing a water molecule. Hydrolysis breaks polymers apart by adding water.
4. Four levels of protein structurePrimary: amino acid sequence. Secondary: alpha helices and beta sheets from backbone hydrogen bonds. Tertiary: overall 3-D fold from side-chain interactions. Quaternary: multiple polypeptides together.
5. Saturated vs unsaturated fatty acidsSaturated fatty acids have no C=C double bonds, pack tightly and are solid at room temperature. Unsaturated ones have one or more cis double bonds that create kinks, so they are usually liquid.
6. How do enzymes speed up reactions?They lower the activation energy by binding substrates at the active site. They do not change the overall free energy change of the reaction and are not used up.
7. Competitive vs noncompetitive inhibitionA competitive inhibitor binds the active site and can be overcome by more substrate. A noncompetitive inhibitor binds elsewhere and changes the enzyme's shape, lowering activity even at high substrate.
8. Prokaryotic vs eukaryotic cellsProkaryotes (bacteria, archaea) lack a nucleus and membrane-bound organelles. Eukaryotes have a nucleus and organelles such as mitochondria and ER. Both have ribosomes, DNA and a plasma membrane.
9. Rough ER, smooth ER and Golgi apparatus functionsRough ER: ribosomes make secreted and membrane proteins. Smooth ER: lipid synthesis and detoxification. Golgi: modifies, sorts and packages proteins for transport.
10. Evidence for the endosymbiotic theoryMitochondria and chloroplasts have their own circular DNA, bacterial-like ribosomes, double membranes and divide by binary fission, suggesting they came from engulfed prokaryotes.
11. Fluid mosaic model of the plasma membraneA phospholipid bilayer with hydrophobic tails inside, in which proteins, cholesterol and glycolipids move laterally.
12. Diffusion vs facilitated diffusion vs active transportDiffusion: down the gradient through the bilayer, no energy. Facilitated diffusion: down the gradient through channel or carrier proteins, no energy. Active transport: against the gradient using ATP (e.g. Na+/K+ pump).
13. What happens to an animal cell in a hypotonic solution?Water enters by osmosis and the cell swells and may burst (lyse). In a hypertonic solution it loses water and shrivels.
14. Overall equation for cellular respirationC6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy (ATP and heat).
15. Stages of aerobic respiration and where they occurGlycolysis in the cytoplasm, pyruvate oxidation and the citric acid (Krebs) cycle in the mitochondrial matrix, and the electron transport chain and oxidative phosphorylation on the inner mitochondrial membrane.
16. What is the role of oxygen in cellular respiration?Oxygen is the final electron acceptor at the end of the electron transport chain, combining with electrons and H+ to form water.
17. How does chemiosmosis make ATP?The electron transport chain pumps H+ across a membrane, building a gradient. H+ flows back through ATP synthase, which uses that energy to make ATP.
18. Fermentation: purpose and productsWithout oxygen, fermentation regenerates NAD+ so glycolysis can continue making 2 ATP per glucose. Products are lactate (muscle) or ethanol and CO2 (yeast).
19. Light reactions vs Calvin cycleLight reactions (thylakoid membranes) split water, release O2 and make ATP and NADPH. The Calvin cycle (stroma) uses that ATP and NADPH to fix CO2 into sugar.
20. What does the enzyme rubisco do?It catalyzes carbon fixation in the Calvin cycle, attaching CO2 to RuBP. It is thought to be the most abundant protein on Earth.
21. Structure of DNAA double helix of two antiparallel strands with a sugar-phosphate backbone. Bases pair by hydrogen bonds: A with T (2 bonds) and G with C (3 bonds).
22. What did the Meselson-Stahl experiment show?Using heavy and light nitrogen isotopes, it showed DNA replication is semiconservative: each new double helix keeps one old strand and one new strand.
23. Leading vs lagging strand in replicationDNA polymerase only adds nucleotides 5' to 3'. The leading strand is made continuously; the lagging strand is made in short Okazaki fragments joined by DNA ligase.
24. Key enzymes of DNA replicationHelicase unwinds the helix, primase lays down RNA primers, DNA polymerase extends and proofreads, and ligase seals gaps between fragments.
25. Mitosis vs meiosisMitosis gives two genetically identical diploid cells for growth and repair. Meiosis gives four genetically different haploid gametes, with crossing over and independent assortment.
26. Natural selection: the necessary conditionsHeritable variation exists, more offspring are produced than survive, and individuals with certain traits survive and reproduce more, so those traits become more common over generations.
27. Homologous vs analogous structuresHomologous structures share common ancestry but may differ in function (human arm, bat wing). Analogous structures have similar function from convergent evolution but different ancestry (bird and insect wings).
28. Hardy-Weinberg equations and conditionsp + q = 1 and p^2 + 2pq + q^2 = 1. Holds with no mutation, random mating, no selection, a very large population and no gene flow.
29. Genetic drift vs gene flowGenetic drift is random change in allele frequencies, strongest in small populations (bottleneck and founder effects). Gene flow is movement of alleles between populations through migration.
30. Biological species conceptA species is a group of populations whose members can interbreed in nature and produce fertile offspring, and that are reproductively isolated from other groups.