BS-GI SYSTEM II

BS -GI SYSTEM II 1. What is the difference in the bonding between alpha-helix and beta sheets? - ANSWER Hydrogen bonding occurs between the amides of adjacent chains in the sheets instead of between the amides in different parts of the helices. 2. Organic molecules have a carbon backbone and _____ such as -OH and NH2 that can form hydrogen bonds - ANSWER functional groups 3. Phospholipids are made up of: - ANSWER a phosphate, two fatty acids and a glycerol. 4. Proteins are polymers formed of structural units called: - ANSWER amino acids. 5. Proteins are created with: - ANSWER peptide bonds. 6. The covalent bonds connecting monomer units in sugars can be formed by the removal of a water molecule. This reaction is referred to as: - ANSWER a dehydration reaction. 7. Common lipids for energy storage are: - ANSWER triglycerides. 8. A DNA strand contains 20 purines and 26 pyrimidines. How many purines will the complementary strand contain? - ANSWER 26 9. α - glucose is present in potatoes and β - glucose is present in wood. Both are glucose molecules but one can be used by humans to synthesize ATP and one cannot. Based on this information, what is the best explanation on why humans can only digest one of the glucose types? - ANSWER α - glucose and β - glucose are stereoisomers with OH groups oriented differently. 10. Egg whites consist primarily of water and the protein albumin. When you fry an egg, why does the egg white turn from clear to white? - ANSWER The protein becomes denatured. 11. Which chemical group forms hydrogen bonds with water and is most likely to explain why sugars dissolve well in water? - ANSWER -O-H 12. Atoms of a single element that possess different numbers of neutrons are called: - ANSWER isotopes. 13. An atom has 20 electrons and 20 neutrons. What is the mass of this atom? - ANSWER 40 14. The reaction (H2 + F2 → 2HF) is an example of a redox reaction. In reality, two half reactions are occurring. The half reaction (H2 → 2H+ + 2e-) is a(n): - ANSWER oxidation reaction 15. In the crystal matrix of ordinary salt, the sodium and chlorine are held together by: - ANSWER ionic bonds. 16. Water molecules are attracted to each other due to the opposite charges created by partial charge separations within the molecules. These attractions are called: - ANSWER hydrogen bonds. 17. The negative logarithm of the hydrogen ion concentration in the solution is referred to as: - ANSWER pH 18. A chemist adds a chemical to pure water and there is a 100 fold increase in the concentration of hydrogen ions. What is the best approximation of the new pH value? - ANSWER 5 19. Water is most dense and thus heaviest at 4oC. At 0oC, ice forms and can float on liquid water. Suppose ice were most dense at 0oC. What would happen in a lake? - ANSWER The ice would cover the bottom of the aquatic system and would build up in layers over time. 20. The accumulation of amino acids and sugars in animal cells can occur through - ANSWER coupled transport. 21. Incubation of cells at 20°C blocks the release of proteins from the trans Golgi. Under such conditions, you would expect to see - ANSWER a decrease in exocytosis. 22. The organelle that can collect, package, modify, and transport molecules is called the: - ANSWER Golgi apparatus. 23. Given what is known about the minimal essential functions of cellular life, if you could create an artificial cell, what cellular structures must you include? - ANSWER ribosomes 24. The evolutionary process that created chloroplasts and mitochondria is: - ANSWER endosymbiosis. 25. A cuboidal shaped cell with six sides is 1mm X 1mm X 1mm. What is the volume and the surface area of the cell? - ANSWER 1mm3 : 6mm2 26. (SA = 6a^2, V =a^3 ) 27. If you added a drug to a suspension of bacteria that inhibited their flagella they would not be able to _____ - ANSWER move. 28. As a plant cell grows a new cell wall the secondary wall forms: - ANSWER between the primary cell wall and plasma membrane. 29. The nucleolus is the site of: - ANSWER ribosome assembly. 30. You have identified an enzyme that appears to be involved in the addition of palmityl group (a fatty acid) to certain proteins. Knowing that palmitoylated proteins are usually targeted for delivery to the plasma membrane, in which organelles might this enzyme be expressed? - ANSWER Golgi apparatus and ER 31. As ATP moves from the matrix of the mitochondrion to the cytoplasm of a cell, how many membranes will it pass? - ANSWER 2 32. When a vesicle moves along microtubules toward the center of the cell, the molecular motor(s) _____ are used? - ANSWER dynein 33. On the outer surface of the plasma membrane there are marker molecules that identify the cell type. Often these molecules are - ANSWER carbohydrate chains. 34. While water continually orients phospholipids into a lipid bilayer, it does not fix the lipids permanently into position. Thus, the bilayer is considered to be _______. - ANSWER fluid 35. The net movement of substances to regions of lower concentration is called - ANSWER diffusion. 36. Osmosis occurs as water can cross the lipid bilayer through specialized channels for water movement called _________. - ANSWER aquaporins 37. A mixed solution of water and ions is exposed to a cell membrane and allowed to interact for an hour. Which would diffuse across a phospholipid bilayer fastest? - ANSWER NH3 38. While eating lobster for dinner one night your friend asks what you think might happen if this marine invertebrate, which is normally isosmotic with respect to the surrounding seawater, were to be moved to a bay with a slightly lower salt concentration instead of being caught. You reply that, in order for the lobster to be isosmotic with respect to new environment, it - ANSWER regulates its internal concentration of solutes to match that of its new environment.