CELL BIO: Please answer as many as you can. I need them to be them 100% correct.
ID: 3166584 • Letter: C
Question
CELL BIO: Please answer as many as you can. I need them to be them 100% correct. if you are at all unsure, please skip it. i dont need an explanation. thank you
48. lac operon, lactose is acting as a In the a. Repressor b. Corepressor c. Inducer d. operator 49. Describe the repressible tryp operon in the absence of tryptophan a. The repressor protein is inactive and transcription is turned on b. The repressor protein is active and transcription is turned of c. The repressor protein is inactive and transcription is turned off d. The repressor protein is active and transcription is turned on 50. Which of the following is not true regarding Epigenetics? a. Epigenetics includes histone modification b. Epigenetics describes the inheritance of genes c. Epigenetics describes the inheritance of patterns chromatin folding d. Epigenetics requires the action of chromatin remodeling complexes 51. Which of the following describes a potential function of cellular membranes? a. Cell communication b. Cell movement c. Selective transport of materials in and out of the cell d, Compartmentalization within the cell e. All of the above 52. What are phospholipids made of? Phosphate head, glycerol backbone, three fatty acid tails a. b. c. d. Phosphate head, glycerol backbone, two fatty acid tails Fatty acid head, glycerol backbone, two phosphate tails Fatty acid head, glycerol backbone, three phosphate tails 53. Which of the following factorís) would decrease membrane fluidity? Longer fatty acid tails in the phospholipids small amounts of cholesterol in the membrane Highly unsaturated fatty acid tails Higher temperatures a. b. d. 54. What is the driving force behind the formation of the phospholipid bilayer? The repelling nature of the hydrophilic tails of the phospholipids and the aqueous environment in a out of the ce# The repelling nature of the hydrophobic tails of the phospholipids and the aqueous environment in and out of the cell The attraction between the hydrophobic heads of the phospholipids and the aqueous environment in and out of the cell The attraction between the hydrophilic heads of the phospholipids and the aqueous environment in and out of the cell nd a. b. c. d. 55. Flippases a. catalyze the movement of phospholipids across the layers of the phospholipid bilayer b. are found on the surface of the ER membrane c. ensure that membranes grow evenlyExplanation / Answer
48. C. Inducer.
49. A. The repressive protein is inactive and transcription is turned on.
When tryptophan levels are low, RNA polymerase binds to the promoter and transcribes the five structural genes into a single mRNA, which is then translated into enzymes that convert chorismate into tryptophan.
51. E. All of the above.
Cell membranes help in transportation of substances, cell communication and compartmentalization of cell.
52.B. Phosphate head, glycerol backbone and two fatty acid tails.
53. Longer fatty acid tails in phospholipids.
The fluidity of a lipid bilayer depends on both its composition and its temperature. The membrane remains fluid and becomes more difficult to freeze if the hydrocarbon chains are short or have double bonds. A shorter chain length reduces the tendency of the hydrocarbon tails to interact with one another, and double bonds produce kinks in the hydrocarbon chains that make them more difficult to pack together, so that the membrane remains fluid at lower temperatures.
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