BIO282 Block 2 Gene Regulation

A lac operon of genotype lacl- lacP+ lacO+ lacZ+ lacY+ will produce b-galactosidase and permease when:

Regardless whether lactose is absent.

A lac operon of genotype lacl+ lacP+ lacO+ lacZ- lacY+ will not produce b-galactosidase but will produce permease when:

Lactose is present and glucose is absent.

In the presence of both lactose and glucose, which occurs with E.coli lac operon:

cAMP CAP complex is not available to bind near the lac promoter.

In the presence of lactose and absence of glucose, which occurs with E.coli lac operon:

lacZ and lacY genes are fully expressed

Which of the following histone modifications is commonly associated with active chromatin?

Acetylation of histone H3 and H4

Which enzyme is responsible for adding acetyl groups to histones?

HAT

Which of the following DNA modifications is associated with transcriptional silencing?

DNA Methylation

What is the role histone deacetylases (HDACs)?

Remove histone groups, leading to chromatin condensation

Which transcription factor binds to TRE elements?

AP1

Azacytidine cause gene activation because:

It cannot be methylated, preventing gene silencing

What are enhancers?

Regulatory DNA sequences that enhance gene expression, they can function thousands of base pairs away from the gene.

What are insulators?

Regulatory DNA sequences that block the effects of enhancers.

What is the role of basal transcription apparatus?

Bind near TATA box to start transcription

What is a mediator complex responsible for?

Connecting activators to RNA polymerase

Transferrin receptor mRNA is protected from degradation when

IRE binding protein is bound to IRE

What is the role of HCI in translation regulation?

Inhibits translation in absence of heme

Which translation initiation factor is inactivated by phosphorylation?

eIF2

Which process leads to reduced mRNA stability?

Deadenylation

GRE (Glucoidal Response Element) is activated by

Steroid-receptor proteins

Which of the following allows differential gene expression in different tissues?

Unique regulatory transcription factors

In ferratin mRNA, the Iron Response Element (IRE) is located:

Upstream of the start codon

Which motif is commonly found in the DNA binding domains?

Zinc Finger and Helix-Turn-Helix motifs

Which motif is commonly found in the Protein interaction domains?

Leucine Zipper and Helix-Loop-Helix

What allows translation of trpD immediately after trpE in polycistronic mRNA?

Coupled Translation

The function of Iron Response Elements (IRE) in ferratin mRNA is to

Block translation initiation factor under low iron

What happens wheniron binds to the IRE-binding proteins in ferratin mRNA?

It loses affinity to the IRE, allowing translation

What effect do rare codons have on translation?

Slows it down due to limited tRNA’s