Each page contains a chemical signal or nutrient. For this assignment, you will
ID: 93673 • Letter: E
Question
Each page contains a chemical signal or nutrient. For this assignment, you will hypothesize how a hypothetical bacterium might use that signal or nutrient to control gene expression. Refer to the lac and trp operons in the textbook for ideas. Consider the following while deciding how the cell will respond: 1) how will the cell know the signal nutrient is present, 2) how will the presence of the signal/nutrient be used to alter gene expression, and 3) what types of gene (or gene function) would the cell be altering. Signal Alanine: The cell has found itself in the presence of alanine. How might this amino acid control gene expression? Nutrient Maltose: The cell has found itself in the presence of maltose. How might this sugar control gene expression? Signal Heme: The cell has found itself in the presence of heme (found in blood). How might this molecule control gene expression?Explanation / Answer
Answer:-The amino acid alanine will control the gene expression for the gene that is transcribed and that codes for the components for production of alanine. The gene is regulated so that when alanine is present in the environment, the genes for alanine synthesis will not be expressed. It will follow repressible negative regulation of gene expression.
Similar to trp operon regulation, alanine gene regulation will occur. In presence of alanine, alanine repressor will bind to alanine. This will change the repressor conformation an will allow the repressor to bind to the operator. This will prevent RNA polymerase from binding to and transcribing the operon, so alanine will not be produced. When alanine is not present, the repressor will remain in its inactive conformation and will not bind the operator region, so transcription will not be inhibited by the repressor.
Answer:- Maltose is a nutrient which cells need to take up. Thus availability of maltose will stimulate the gene expression for enzymes which can digest maltose and aid in uptake of maltose by the cell. Specific control of the gene will depend on the availability of the substrate maltose to the cell. The type of regulation that will undergo is negative inducible, meaning that the gene will be turned off by the regulatory factor (repressor) unless maltose is added. It will be waste of enzymes, if maltose is not present for the uptake. Thus absence of maltose stimulates production of repressor which in turn stops production of enzymes needed for uptake of maltose. The functioning will be similar to lac operon.
Heme is the product of hemoglobin degradation. Heme is a pro-oxidant that influences a variety of cellular processes. An iron- and reactive oxygen species (ROS)-independent signalling is induced by heme. This comprised genes related to redox metabolism. Heme possibly acts as a danger signaling molecule. Heme-mediated effects on gene expression are thought to be related to oxidative stress.
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