1A) What biological molecule is present in all membranes of the cell? (1word) phospholipids 1B) What makes the membranes of a cell (e.g. the plasma membrane, the mitochondrial membranes, the golgi membranes, etc.) different from one another? (1 short phrase) they contain different proteins 1C) What two functions do all membranes in a cell have in common? (2 short sentences) 1. Membranes serve as barriers between one cellular space and another (or between the outside of the cell and the inside). 2. Membranes are selectively permeable. 2) Name 4 different things that proteins do in cells: enzymes motor proteins (chemical energy converted into movement) cytoskeletal proteins (act as structural elements) transport proteins or channels in membranes package DNA in chromosomes receive signals transduce signals more answers are possible 3) Explain the hydrophobic effect, i.e. the effect that prevents oil from mixing with water (a few sentences and maybe a diagram): Due to the strong electronegativity of oxygen, water is an extremely polar molecule (diagram). The unequal sharing of electrons in the water molecule results in individual water molecules being strongly attracted to one another through hydrogen bonding. Water molecules form a extensive hydrogen bonding network with each other ; this network excludes molecules that do not hydrogen bond or otherwise interact with water (this is the definition of a hydrophobic molecule), causing them to crowd together. 4) Explain how a non-spontaneous reaction can be made to occur inside a cell (one sentence): An enzyme can use the energy released from a spontaneous reaction (exergonic) to drive a non-spontaneous (endergonic) reaction. 5) What is the major energy transfer molecule of a cell? (one word) ATP6) This is the overall chemical equation for the oxidation of glucose, whether it occurs inside a cell or on a lab bench by burning glucose: C6H12O6 + 6O2 6CO2 + 6H2O However, when you burn something, you release a lot of heat and light. Why don’t cells burn up when oxidizing glucose – what happens to the energy released? (one sentence) Glucose is oxidized by a stepwise process in the cell, with each step releasing a small amount of energy that is trapped and eventually used to synthesize ATP. 7) These questions refer to the chemical structures drawn on the last page. 7A) Which structure(s) are sugars? #1, 4, 6, 12, 15 and I’ll take 14 as correct also. 7B) Which structure(s) are either fatty acids or contain fatty acids as part of a larger structure? #5, 9 7C) Which structure(s) contain amino groups? #2, 7, 8, 13 7D) Which amino acid structure can NOT form two enantiomers? #8 7E) Draw three possible isomeric forms (isomers) derived from structure #3: 8) TRUE or FALSE. More than 8 different elements are naturally found in the human body. True 9) If solution A has 5000 times as many hydrogen ions as solution B, by approximately how many pH units do they differ? Somewhere between 3 and 410) How is the DNA in a eukaryotic cell organized relative to DNA in a prokaryotic cell? (one sentence) DNA in a eukaryotic cell is contained in chromosomes, DNA in a prokaryotic cell is not. I will also accept the answer that DNA in a eukaryotic cell is enclosed in the nucleus, while DNA in a prokaryotic cell is not. 11) What is the function of cytoplasmic ribosomes? (one sentence) Cytoplasmic ribosomes make proteins that will stay in the cytoplasm and function there, such as the enzymes of glycolysis, microtubules, etc. 12) Draw a diagram of a mitochondrion, and label the various regions. Indicate the processes that generate energy in the mitochondrion, and give these processes their proper name and location. Also indicate what region of the mitochondrion has the lowest pH. The diagram should show an outer membrane, an inner membrane which is highly infolded, and the mitochondrial matrix. It should indicate that the Citric Acid cycle is in the matrix, the electron transport chain is in the inner membrane, and ATP synthetase uses a flow of hydrogen ions from the intermembrane space back to the matrix (or uses the term chemiosmosis in conjunction with showing the hydrogen ion flow). It should show that the intermembrane space has the lowest pH (highest concentration of hydrogen ions). 13) Why do electrons flow from one carrier molecule to the next carrier molecule in an electron transport chain? (one sentence) Each succeeding carrier molecule in an electron transport chain has a higher affinity for electrons than the carrier molecule that preceded it. 14) What molecule is the immediate source of the electrons that are fed into the electron transport chain? NADH (also FADH2, but it isn’t necessary to state this) 15) What is the source of the molecular oxygen that is released as waste during photosynthesis? (one sentence) O2 is liberated from water that has been split using light energy.16) You are studying the following series of enzymatic reactions: A B C D Enzyme X Enzyme Y Enzyme Z In words, substance “A” is converted to substance “B” by “Enzyme X”. Substance “B” is then converted to “C” by “Enzyme Y”, and finally “Enzyme Z” converts “C” to “D”. You have all of these enzymes and chemicals A, B, C and D in pure form. You have ways of analyzing which ones of these chemicals exist in the reaction mixture, and how much of each exists. Since many enzymatic cascades are inhibited by the final product, you hypothesize that chemical “D” feeds back on to “Enzyme X” and inhibits its activity. How could you test this hypothesis? (short paragraph, about 4 sentences) You could make two reaction mixtures: 1) has chemical “A” and “Enzyme X”……over time, you can measure the appearance of chemical “B” as it is generated. 2) is the same as 1) above, except that you also add a large amount of chemical “D” to the mixture. If chemical “D” inhibits “Enzyme X”, this second reaction should generate “B” much more slowly than the first reaction, or generate no “B” at all. 17) A protein kinase is a type of enzyme that acts in cell signaling. Like any enzyme, it has substrate(s) and product(s). What is/are the substrate(s) for protein kinases? ATP and a target protein What is/are the product(s)