QUESTION 5 Which of the following genes is LEAST likely to be expressed in all b

Question

QUESTION 5 Which of the following genes is LEAST likely to be expressed in all bacteria at all times?

a. RNA polymerase

b. The ribosomal

c. RNA genes tRNA genes

d. The lac operon

e. The sigma factor

QUESTION 6 What role does the lac operator play in regulating gene expression?

a. The operator contains the genes needed to synthesize the lactase enzyme

b. The operator is a protein that binds to DNA in the presence of lactose

c. The operator is a transcriptional activator that turns on lactase synthesis

d. The operator is the DNA sequence bound by the lac repressor

QUESTION 7 If a bacterium does not have glucose available, where will the lac activator be located?

a. It will be released from the lac operon

b. It will bind within the protein-coding genes of the lac operon

c. It will be bound to DNA upstream from the lac operon genes

d. It will bind to the lac repressor

QUESTION 8 In human cells, how can scientists turn specialized cells from an adult into stem cells?

a. Use somatic cell nuclear transfer to transfer stem-cell DNA nuclei into adult cells

b. Express transcription regulators that are normally found in stem cells in the differentiated cells

c. Use chromatin remodeling enzymes to condense the chromatin of the adult cell until it resembles a stem cell

d. Fuse the stem cell with the adult cell to perform somatic cell nuclear transfer

QUESTION 9 What is the role of cyclic AMP in the regulation of the lac operon?

a. cAMP is the activator that turns on gene expression

b. cAMP binds to the lac repressor when lactose is present

c. cAMP provides the energy to remove the repressor from the lac operon

d. cAMP binds to the lac activator when glucose is unavailable

QUESTION 10 What type of molecule triggers RNA interference (RNAi)?

a. single-stranded DNA

b. double-stranded DNA

c. double-stranded RNA

d. a DNA:RNA hybrid helix

Explanation / Answer

Which of the following genes is LEAST likely to be expressed in all bacteria at all times?

Lac operon: The lac operon expresses only when there is a lack of glucose in cell. Lac operon break down lactose into glucose.

What role does the lac operator play in regulating gene expression?

The operator is the DNA sequence bound by the lac repressor: When lactose is absent, lac repressor binds to operator and suppress the genes expression responsible for synthesis for glucose but when lactose is present, lactose binds with the lac repressor leaving the operator free for expression.

If a bacterium does not have glucose available, where will the lac activator be located?

It will bind within the protein-coding genes of the lac operon: The lac activator here refers to the catabolic gene activator protein (CAP). CAP with cAMP binds in the operator and facilitate gene expression.

In human cells, how can scientists turn specialized cells from an adult into stem cells?

Express transcription regulators that are normally found in stem cells in the differentiated cells: Oct4 and Nanog are transcriptional regulator associated with maintaining the stem cells in an undifferentiated state, capable of self- renewal. Adult cell can be converted to stem cell by stimulating these transcriptional regulators.

What is the role of cyclic AMP in the regulation of the lac operon?

cAMP is the activator that turns on gene expression: CAP with cAMP binds in the operator and facilitate gene expression.

What type of molecule triggers RNA interference (RNAi)?

double-stranded RNA: RNAi are processed dsRNA molecules.

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