Regulation of Gene Expression in E. coli

*E. coli* have another method to regulate the genes in the *trp* operon. This method is referred to as attenuation. In this method, when levels of tryptophan are high, RNA polymerase begins transcription but then stops when it reaches the leader section. In this case, will the enzymes for tryptophan synthesis be produced?

• Yes, the enzymes will be produced.

• No, the enzymes will not be produced.

• Only some enzymes will be produced.

• The production of enzymes is not affected by attenuation.

Identify the operator, RNA polymerase, and trp repressor gene on the diagram 1.

• Operator is labeled as A, RNA polymerase as B, and trp repressor gene as C.

• Operator is labeled as B, RNA polymerase as C, and trp repressor gene as A.

• Operator is labeled as C, RNA polymerase as A, and trp repressor gene as B.

• Operator is labeled as A, RNA polymerase as C, and trp repressor gene as B.

Structural genes control the activity of various metabolic activities within a cell by:

• Encoding enzymes that catalyze metabolic reactions

• Regulating the cell cycle

• Transporting molecules across cell membranes

• Providing structural support to the cell

Regulatory genes may activate or deactivate more than one structural gene or cluster of structural genes. Which of the following best describes this process?

• Regulatory genes bind to specific DNA sequences to control gene expression.

• Regulatory genes are involved in the replication of DNA.

• Regulatory genes are responsible for protein synthesis.

• Regulatory genes do not interact with structural genes.

The promoter region on a gene:

• is the area a repressor can bind to.

• is an area that RNA polymerase can bind to.

• is translated.

• binds to the operator to control gene expression.

State the main reason for gene regulation in organisms such as *E.coli*.

• To conserve energy by producing only necessary proteins

• To increase mutation rates

• To enhance genetic diversity

• To promote constant protein production

When tryptophan levels are high, how does the trp operon function?

• The trp operon is activated to produce more tryptophan.

• The trp operon is repressed to stop the production of tryptophan.

• The trp operon is unaffected by tryptophan levels.

• The trp operon increases the breakdown of tryptophan.

The next 2 questions refer to the following information relating to the trp operon. Structure 4 is:

• Trp genes

• Promotor

• Operator

• Repressor

Discuss evidence from the diagram that shows that the proteome has many more polypeptides than the genome has genes.

• The diagram shows alternative splicing of genes.

• The diagram indicates post-translational modifications.

• The diagram illustrates gene duplication events.

• The diagram highlights the presence of non-coding RNA.

When comparing the genome of a eukaryotic cell to the proteome of the same eukaryotic cell, it would be reasonable to state that the

• genome and the proteome are the same.

• genome would be the same for the life of the cell.

• proteome would be the same for the life of the cell.

• proteome provides the blueprint for the genome of the cell.