Chapter 14 Smartbook

Sequence the steps that activator proteins take to promote the unraveling of compact chromatin at the site of gene transcription. Start with the first step at the top of the list.

1. Transcription activator binds to an open enhancer site 2. Activators recuit chromatin remodeling proteins 3. Compacted chromatin is loosened 4. Transcription occurs

What is an operon?

A cluster of genes under the transcriptional control of a single promoter

How do activators and repressors regulate the function of RNA polymerase in eukaryotes?

Activators and repressors interact with GTFs or mediator proteins.

How do activator proteins diminish the level of chromatin compaction at the site of the gene that is to be transcribed?

Activators bind to an enhancer site and then recruit other proteins to unravel and loosen the packed chromatin.

Which of the following is a form of gene regulation in which a eukaryotic pre-mRNA can be processed to produce more than one mature RNA?

Alternative splicing

The lac operon is also under positive control by an activator protein called what?

CAP

An activator protein recognizes the ______ of the lac operon.

CAP site

The enzyme responsible for covalently attaching methyl groups to DNA is _____ _______

DNA methylase

True or false: In multicellular organisms, genes are regulated in the same way to ensure that gene expression levels are constant regardless of cell type or developmental stage.

False

The functional product of genes arises from what process?

Gene expression

______ is the main protein that delivers oxygen to cells of a mammal's body.

Hemoglobin

How does allolactose affect the lac repressor protein?

It binds to the repressor protein and prevents it from binding to the operator site of the lac operon.

What is the effect of low levels of tryptophan on the transcription of the trp operon?

Low levels of tryptophan will result in high levels of transcription.

Which of the following is a common modification that affects the structure of DNA?

Methylation

How can gene regulation be specific? Multiple select question. Specific gene sequences are present in the DNA of different cell types. Specific genes are expressed at different developmental stages. Specific genes are expressed only in certain cells. Specific genes differ in expression levels from cell to cell.

Specific genes are expressed at different developmental stages. Specific genes are expressed only in certain cells. Specific genes differ in expression levels from cell to cell.

The two components that make up the core promoter are the _______ box and the transcriptional start _______

TATA site

What is the function of the genes that are expressed in the lac operon of E. coli?

The metabolism of lactose

What is cell differentiation?

The process by which cells become specialized in different types

What is the function of ATP-dependent chromatin-remodeling complexes?

They cause a change in the locations and/or compositions of nucleosomes.

A nucleosome-free region (NFR) is ______.

a site on a chromosome that is missing nucleosomes

The process whereby different transcripts are made from a single gene is called

alternative splicing

Cell ______ is the process by which cells become specialized into particular types.

differentiation

Polycistronic mRNA ______.

encodes more than one protein

Many eukaryotic genes are flanked by a site that is missing nucleosomes. This site is known as a nucleosome-

free region

In mammals, the protein which delivers oxygen to body cells is

hemoglobin

Covalent modifications of histones are a language directing interactions between histones and DNA. This statement is a summary of the _______ _______ hypothesis.

histone code

Transcription of the trp operon is ______ when levels of tryptophan are low in the cell.

increased

In mammals, when iron levels are high, iron binds to the iron regulatory protein. This results in ______.

increased translation of ferritin

In E. coli, the genes required to metabolize lactose are expressed ______.

only when lactose is present

In the lac operon, the _______ is the DNA sequence at which the lac repressor binds.

operator

The lacO of the lac operon is the site where the repressor protein binds. It is referred to as the

operator

A(n) ________ is a cluster of genes that are part of a single transcription unit that is under the control of a single promoter.

operon

Regulatory transcription factors influence the expression of genes by affecting the rate of transcription. They do so by binding directly to DNA at or near the ________ site.

promoter

Regulation of prokaryotic gene expression typically involves all of the following mechanisms EXCEPT: regulation of transcription modifications to proteins after translation regulation of RNA processing regulation of translation

regulation of RNA processing

What are regulatory transcription factors?

Proteins that bind to DNA and affect the transcription of one or more genes

Eukaryotic gene expression can be regulated at which levels? Multiple select question. RNA modification Translation Replication Transformation Transcription

RNA modification Translation Transcription

The lac repressor protein prevents the transcription of the lac operon genes by the enzyme

RNA polymerase

Match each protein or group of proteins with its role in transcription. Instructions

RNA polymerase -Synthesis of RNA from a DNA template General transcription factors - Required for binding to the core promoter and initiating transcription Activators - Binding to enhancer sequences and interaction with other proteins

Why are interactions between RNA polymerase II and GTFs important for transcription in eukaryotes?

RNA polymerase II and GTFs must interact for the polymerase to bind properly at the core promoter site of the DNA.

What molecules can influence transcription by binding to enhancers or silencers?

Repressors and activators

What are the two components of the core promoter? Multiple select question. GC box Translational start site TATA box Mediator site Transcriptional start site

TATA box Transcriptional start site

In order for transcription of protein coding genes in eukaryotes to begin, the promoter must have several key features. What are they?

TATA box, regulatory elements, transcriptional start site

What is chromatin?

The complex formed by DNA and its associated proteins

What is the role of the corepressor in the expression of the trp operon?

The corepressor binds to the repressor protein and causes a conformational change, which allows the repressor to bind to the operator site.

When are the genes involved in lactose metabolism in E. coli expressed and when are they turned off?

The genes for lactose metabolism are expressed when lactose is present but not when it is absent.

The binding of the corepressor to the trp repressor results in what?

The repressor binds to the operator and prevents transcription.

What is the role of the repressor protein in the transcription of the trp operon?

The repressor protein binds to the operator site and prevents the transcription of the trp operon.

What is the CAP site for the lac operon?

The sequence of nucleotides that is recognized by an activator protein

What is the function of the genes encoded by the trp operon?

The synthesis of the amino acid tryptophan

At what levels does gene regulation occur in prokaryotes? Multiple select question. Transcription Translation Replication mRNA processing Post-translation

Transcription Translation Post-translation

Both prokaryotes and eukaryotes use _______ proteins to regulate the process of transcription.

activator and repressor

Match the features of transcriptional regulation on the left to the organisms using them on the right. Instructions

activator and repressor proteins regulate genes - prokaryotes and eukaryotes genes organized individually - eukaryotes genes organized in operons - prokaryotes

A conformational change in the lac repressor protein occurs upon binding of the sugar _________ to it. This change in shape prevents the repressor from binding to the _________ site.

allolactose operator

DNA and its associated proteins form a compact structure called ______.

chromatin

Proteins that use energy from ATP hydrolysis to change the locations and compositions of nucleosomes are called ATP-dependent ______ - ________ complexes.

chromatin remodeling

The process in which the information in a gene is made into a functional gene product, such as an RNA molecule or a protein, is termed gene

expression

The genes found in the lac operon of E.coli are used for the metabolism of

lactose

An mRNA that encodes more than one protein is called _______ mRNA.

polycistronic

The catabolite activator protein (CAP) is involved in ______ control of the lac operon.

positive

Bacteria and eukaryotes can regulate genes at the level of transcription. In eukaryotes, gene expression is also commonly regulated at the levels of RNA ________ and translation.

processing/modification

The trp operon is regulated by a(n) ________ protein that is encoded by the trpR gene.

repressor

The transcription of the lac operon genes is inhibited when the lac repressor protein binds to ______.

the lac operator

According to the histone code hypothesis, proteins recognize histones based on ______.

their covalent modifications

In mammals, iron toxicity is prevented by regulating the ______ of ferritin.

translation

The genes in the trp operon encode enzymes that make the amino acid

tryptophan