Solved by a verified expert:1.The structure of biological membranes is determined primarily by the lipid bilayer but thespecific functions of these membranes are carried out by proteins associated with themembrane. State whether you believe this statement is True or False and explain youranswer.2. Would you agree or disagree with the statement that differences in gene expressionpatterns can always be attributed to a difference in DNA sequence?3. The mitotic Cdk cycle is depicted in the figure below. How does the mitotic Cdk-cyclinbecome active, i.e. what chemical reaction(s) must take place to convert the inactivemitotic Cdk-cyclin to the active mitotic Cdk-cyclin complex? What do you think wouldhappen if the Anaphase-promoting complex were unable to function for some reason?Please explain your answers.4. You have cloned the gene for a transcription factor. You notice that the proteinencoded by the gene for the transcription factor can dimerize (2 copies of the proteincome together to form a complex) and form a leucine zipper motif. The sequenceadjacent to the leucine zipper motif is enriched in positively charged amino acids (see Page9 of11diagram below). Do you think the ability of your transcription factor to function as atranscription factor would be affected if you:i. a). change the hydrophobic leucine motifs in the “zipper” to more polaramino acids. Why or why not?ii. b. change the positively charged amino acids (shown in subunits 1 and 2)to non-charged amino acids. Why or why not?5. cAMP (cyclic AMP) is a secondary messenger (diffusible in the cytoplasm of the cell)involved in cell signaling processes. Describe in as much detail as possible how thissecondary messenger is generated in response to cell signals and how it functions tomodulate downstream events in cell signaling pathways-including changes in geneexpression. Start your discussion by describing the class of cell surface receptorassociated with increases in this second messenger and note in your response at leastone step in signal transduction process where the signal initiated at the cell surface isamplified.6. You have learned that the chemical nature of the side chains of amino acids (polar,nonpolar, charged) are important in determining overall protein structure. Given this, whydo you think that addition of phosphate groups to proteins (as occurs during signaltransduction) might affect protein structure/activity?
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