1. a) Define gene regulation. (2pts) What are two ways gene regulation can be co

Question

1. a) Define gene regulation. (2pts)

What are two ways gene regulation can be controlled in a cell? (2pts)

Is gene regulation found in all organisms? Do you think gene regulation is necessary in organisms? Explain your answer. (2pts)

2. The blob operon produces enzymes that convert compound A into compound B. The operon is controlled by a regulatory gene S. Normally these enzymes are synthesized only in the absence of compound B. If gene S is mutated, the enzymes are synthesized in the presence of B and in the absence of B.

Does gene S produce an activator or a repressor of the blob operon? (2pts)

Is this operon inducible or repressible? (2pts)

3. Under which of the following conditions would the lac operon produce the greatest amount of b-galactosidase (gene Z in the lac operon)? The least? Explain your reasoning for each answer. (3pts)

.....................Lactose Present............................... Glucose present

Condition 1....... Yes........................................................ No

Condition 2........ No....................................................... Yes

Condition 3....... Yes...................................................... Yes

Condition 4....... No....................................................... No

Explanation / Answer

1) the gene is responsible for producing functional proteins. any mechanism by which the expression of gene upregulates or downregulate is called gene regulation.

basic two ways are either induce the gene expression or repress the gene expression.

gene regulation is found in all organisms. this is a way by which cells are saving energy by forming only those proteins which are necessary at the moment. protein synthesis is expensive in terms of energy consumption.

2) blob operon produces a regulatory protein S and in the absence of B, it is on. means protein S is produced as an inactive form and B acts as corepressor which when binds to S and stops the blob operon. this is a repressible operon.

3) we all know that lac operon is an inducible operon which means it is active in presence of lactose.

a)  when glucose is absent and lactose is present. lactose will bind to repressor and inactivate it. operon is on. and produces beta-gal protein.

b) when glucose is present and lactose is absent then repressor is bound with lac operator hence operon is off. no production of beta-gal protein.

c) when glucose and lactose both present . first it will utilize the glucose. at this time lac operon is off. when glucose is consumed then lac operon is on and it will produce beta-gal protein.

d) when both are absent . operon is off. no production of beta-gal.

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