BIO 101 - Organic Macro-Molecules and Membranes Assignment PDF

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Assignment Questions: 1. What is the most familiar way that atoms and molecules are held together? (1 mark) The most familiar way by which atoms and molecules are held together is, the covalent bonds. 2. How does the energy of a covalent bond compare to the thermal energy at body temperature? (2 marks) The energy of the covalent bond is very high at roughly 80 kilocalories per mole, as opposed to the thermal energy at body temperature at about 0.6 kilocalories per mole. 3. What is the significance of the energy level of covalent bonds for organisms? (1 mark) The energy level of covalent bonds is significant for organisms because the high energy level allows molecules to survive over long periods of time as well as, live under very difficult conditions. 4. Is the delta charge on a polar molecule a full electronic charge? (1 mark) Due to unequal distribution, the delta charge on a polar molecule is not a full electronic charge, but instead it is only a fraction. 5. What is the importance of polar molecules for biochemistry? (1 mark) Polar molecules are important in biochemistry due to their ability to dissolve certain compounds. 6. What molecules have important consequences for biological membranes? (1 mark) Non-polar molecules have important consequences for biological membranes. 7. Why are these molecules important for biological membranes? (1 mark) This is because, non-polar molecules have large arrays of carbon-carbon bonds, which are relatively insoluble in water. 8. Is a hydrogen bond more or less energetic than a covalent bond? (1 mark) A hydrogen bond is less energetic than a covalent bond. 9. In real life ( which diagrams cannot really show), what are the hydrogen atoms in water doing in relation to the oxygen atoms? (1 mark) What actually happens in real life is, that hydrogen atoms might be bouncing back and forth between water and oxygen atoms. 10. Why does water not vaporize (become a gas) at room temperature? (1 mark) Because the water molecules have a strong affinity for one another, it is unable to vaporize at room temperature. 11. When water boils, what effect does this level of thermal energy have on the hydrogen bonds? (1 mark) When water boils, the thermal energy is high enough to rip these associations apart. 12. Will a non-polar molecule, like pentane, form any hydrogen bonds with water molecules? (1 mark) A nonpolar molecule, such as pentane, will not form any hydrogen bonds with water molecules. 13. If pentane is added to water, what happens? Because of the deficiency of electronegativity (or positivity) of pentane, it will not be able to form hydrogen bonds, due to the lack of bonding. Also, if you were to put this in a solution of water, this will cause the molecules to line-up, almost quasicrystal around the aliphatic molecule. 14. Is entropy increased or decreased when pentane is added to water? Entropy is decreased when pentane is added to water, due to the aliphatic molecules (of the pentane) not forming any hydrogen bonds with the water molecules.

15. What are the two reasons that an aliphatic molecule like pentane does not ‘like' to be in water? (2 marks) Firstly, an aliphatic molecule like pentane does not like to be in water because it’s unable to form hydrogen bonds with the solvent. Secondly, there is a decrease in the entropy when this molecule directly interacts with water. 16. Is a molecule with a carboxyl group on it hydrophobic or hydrophilic? Molecules that have carboxyl group on it would be called hydrophilic. 17. Do hydrophobic and hydrophilic tendencies have an affect on the overall behaviour of molecules? These hydrophobic and hydrophilic tendencies typically have great effects on the overall behaviour of molecules. 18. Is it possible for one molecule to have a hydrophobic end or area and a hydrophilic end or area? Yes, it is possible. 19. What happen s if thousands or millions of molecules, each having two long hydrophobic tails on one hydrophilic head, are put into water? When thousands or even millions of molecules, each having two long hydrophobic tails on one hydrophilic head are put into water, the head will be attracted to the water molecules and be compelled to immerse itself in the water. Whereas, the hydrophobic tails will attempt to flee the water and associate with one another. 20. What is the structure formed, in water, by molecules with hydrophobic tails and hydrophilic head, for example, by soap molecules in water? The structure formed, in water, by molecules with hydrophobic tails and hydrophilic head by soap molecules in water are called, micelle. 21. Biological membranes separate what? Biological membranes separate two hydrophilic or two aqueous spaces, 22. In eukaryotic cells, there is an enormous premium placed on what? In eukaryotic cells, there is an enormous premium placed on separating and segregating different aqueous compartments. 23. The membrane of cells and cell vesicles are how many layers thick? and are called what? The membrane of cells and cell vesicles are three layers thick, and are called 24. Are there ever mono- layers (single layer, like a soap bubble) of lipids in living cells? Why or why not? (2 marks) No, there are never mono-layers of lipids in living cells. Instead, it’s actually a lipid bilayer with an aqueous inside and on the outside. 25. Much of the thermodynamic stability that allows cells and cell vesicles to remain intact, rather than diffuse apart, is maintained by what? Much of the thermodynamic stability that allows cells and cell vesicles to remain intact, rather than diffuse apart, is maintained by hydrophilic and hydrophobic forces which tie such molecules together or will rip them apart. 26. Pulling out one net molecule of water does what to two small molecules? A covalent bond is created between the two.

27. To create a triglyceride, what two functional groups are acted upon by esterification? Hydroxyl and carboxyl groups are acted upon by esterification to create triglyceride. 28. What is a triglyceride made up of? A triglyceride is made up of glycerol and is esterified. 29. If the third fatty acid is replaced by a phosphate group, this results in an extremely potent hydrophilic or hydrophobic head? If the third fatty acid is replaced by a phosphate group, this results in an extremely potent hydrophilic entity. 30. What important ability do phospholipid bi-layers give to cell membranes? Phospholipid bi-layers give cell membranes the ability to segregate content on one of the other side of whatever lipid bilayer it happens to have constructed. 31. What does permeability refer to? Permeability refers to the ability of this membrane to obstruct or to allow the migration of molecules from one side to the other. 32. Are ions hydrophobic or hydrophilic? why? Ions are highly hydrophilic by virtue of their change. 33. Put the following ions and molecules into this chart: water, ions (Na + , Cl - , K + , Ca 2+ , etc.), amino acids, ATP, glucose (5 marks) Can passively diffuse across cell membrane

Cannot passively diffuse across cell membrane

water

ions amino acids ATP glucose

34. What is the advantage is given to a cell by substances that cannot passively diffuse across the cell membrane? The advantage given is that it can create great gradients in the concentrations of different kinds of ions. 35. Virtually all the energy that is expended in our brain, and more than half of our metabolic burden every day, is expended to do what? Virtually all the energy that is expended in our brain, and more than half our metabolic burden everyday is expended just keeping the ions segregated on the outside and inside of cells. 36. Describe cell membrane channels. Cell membrane channels are little doughnut shaped objects which are placed, inserted into lipid bilayers in plasma membranes. 37. What do channels do? Channels allow for the passive diffusion of an ion through them. 38. What may cells use to control channels? Cells may use a gating mechanism in order to open or close channels.

39. Carbohydrates are made up of what ratio of carbon, hydrogen, and oxygen atoms? Carbohydrates have one carbon atom for every water molecule. 40. How many carbon does a glucose molecule have? Glucose has six carbon atoms. 41. The stereochemistry of a molecule is dictated by what? The stereochemistry of a molecule is dictated by the flexibility with which participating atoms can form bonds. 42. One of the six points on the cyclic structure of glucose is not a carbon atom but a ______atom. Oxygen 43. What is the same and what is not the same in fructose and galactose? There is exactly the same number of carbon atoms, hydrogen atoms and oxygen atoms. However, they are hooked up slightly differently. 44. Do molecules with different stereochemistry function the same way? No, molecules with different stereochemistry function differently from each other. 45. The catalysts that we call enzymes ensure what, in regard to glucose and galactose? Enzymes ensure that one can convert one of these hexoses through an enzyme. 46. What is the name of milk sugar? The name of milk sugar is lactose. 47. What is the name of the enzyme that catalyzes the breakdown of milk sugar into two monosacharides? The name of the enzyme that catalyze the breakdown of milk sugar into two monosaccharides is called, lactase. 48. Compare the number of bacteria in the human gut with the number of cells in the human body. There are more bacteria in the human gut than the cells in the rest of our body. 49. Can the enzyme sucrase break down lactose? Why or why not? No, it cannot break down lactose. This is due to the stereochemical differences. 50. Very long linear aggregates of monosaccharides ,end-to-end or with side branches, are called what? They are known as, polymers....