Topic 6.5 Gene Regulation (Operons)

Why is it important for genes to be regulated?

• It is important for genes to be regulated to maintain proper cellular functions and responses.
• Gene regulation is only important in multicellular organisms.
• Regulated genes can lead to uncontrolled cell growth.
• Genes do not require regulation for cellular functions.

What is gene regulation?

• Gene regulation is the control of gene expression in cells.
• Gene regulation is the study of genetic mutations.
• Gene regulation refers to the physical structure of genes.
• Gene regulation is the process of DNA replication.

What types of organisms use operons to control gene expression?

• Prokaryotic organisms, such as bacteria.
• All eukaryotes

• Viruses that replicate within host cells.
• Eukaryotic organisms, such as plants.

What role does RNA polymerase play in gene expression?

• RNA polymerase synthesizes RNA from a DNA template during transcription, playing a crucial role in gene expression.
• RNA polymerase breaks down RNA during translation
• RNA polymerase transports proteins to the ribosome
• RNA polymerase is involved in DNA replication

Where does RNA polymerase bind to on DNA?

• Exon region of DNA
• Intronic region of DNA
• Promoter region of DNA
• Telomere region of DNA

What role does the operator and the repressor play in gene regulation?

• The operator enhances gene expression, while the repressor activates the gene.
• The operator is a protein that promotes transcription, while the repressor binds to RNA.
• The operator and repressor both facilitate gene expression by promoting transcription.
• The operator controls access to the gene, while the repressor inhibits gene expression when it binds to the operator.

What does the lacI gene do on the lac operon?

• The lacI gene promotes transcription of the lac operon.
• The lacI gene encodes the lac activator, which enhances transcription.
• The lacI gene encodes the lac repressor, which inhibits transcription of the lac operon.
• The lacI gene is involved in the metabolism of glucose.

Why is it important for the repressor to be bound to the opertor of the lac operon when there is no lactose in the environment?

• The repressor must be bound to enhance gene expression when lactose is absent.
• The repressor binds to the operator to allow for increased energy production.
• The repressor is needed to promote the uptake of lactose in the environment.
• It is important for the repressor to be bound to the operator to prevent unnecessary gene expression and conserve energy when lactose is not present.

When lactose enters the environment of the cell what happens to the repressor and the genes on the lac operon?

• The repressor is inactivated and the genes on the lac operon are expressed.
• The repressor is inactivated but the genes on the lac operon are not expressed.
• Lactose has no effect on the repressor or the lac operon genes.
• The repressor is activated and the genes on the lac operon are silenced.

Identify the components of the trp operon structure.

a

b

c

d

e

f

g

RNA Polymerase

Promoter

Tryptophan

Operator

Structural Genes

Repressor Protein

mRNA

Tags

NGSS.HS-LS1-1