Biology chapter 16

Within its core a nucleosome contains ____ histones.

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What is the difference between a gene that is derepressed and one that is induced?

A gene that is derepressed is turned on because a repressor protein is not bound without its cofactor. By comparison, a gene that is induced is turned on because an inducer molecule prevents binding of the repressor.

A protein that initiates gene transcription and allows for non-glucose molecules to be used is

CAP.

You are studying the effects of specific transcription factors on the activation of gene expression. You notice that one particular transcription factor binds far away from the promoter of its target gene. What can explain this?

DNA looping brings the transcription factor closer to the promoter and initiates gene transcription.

Regulatory proteins can identify specific sequences on the DNA double helix without unwinding the helix. This is accomplished by inserting

DNA-binding motifs into the major groove of the double helix where the edges of the nitrogen bases protrude.

Your research project involves the characterization of a recently identified transcription factor. As part of your project, you want to determine if this transcription factor binds directly to any of the general transcription factors. Unfortunately, you are having trouble expressing the full-length protein. What approach may help achieve your research goal?

Express and purify only the activation domain, and test for binding.

In your research, you have discovered that Protein X is often ubiquitinated in people with a certain disease. What would you predict about levels of Protein X in these patients?

Levels of Protein X will be low due to degradation in the proteasome.

The gene encoding apolipoprotein B exists in two isoforms, APOB100 and APOB48. These two forms are produced as a result of

RNA editing.

In order for transcription to be initiated

RNA polymerase must have access to the DNA double helix and must also be capable of binding to the gene's promoter.

The TFIID complex is formed by

TATA-binding protein TBP and TAFs.

The binding of TFIID is followed by the binding of a number of other general transcription factors. The correct order of binding of these factors would be

TFIIB-TFIIA, TFIIF, TFIIE, TFIIH, TFIIJ

Many factors bind around the core promoter to form the eukaryotic initation complex, but the most important one is ______, which directly binds the TATA box.

TFIID

If a strain of bacteria had a mutation that blocked expression of the lac repressor, what would you expect as a result?

The mutant strain would waste energy producing enzymes in the absence of lactose.

You are studying regulation of a prokaryotic operon. Experiments show that expression of the operon is increased when levels of biosynthetic product from that pathway are low. Based on this information, what is a likely mode of regulation?

The product binds a repressor, allowing it to bind the operator.

When E. coli cells produce the amino acid tryptophan, a cluster of five genes is transcribed together. This cluster of genes is referred to as the

When E. coli cells produce the amino acid tryptophan, a cluster of five genes is transcribed together. This cluster of genes is referred to as thetrp operon.

In eukaryotes, specific transcription factors have two distinct domains:

a DNA-binding domain and an activation domain.

The primary transcripts in eukaryotes are most accurately described as

a faithful copy of the entire gene including exons and introns.

Elucidation of the histone code might

allow us to turn specific genes on or off.

If you were able to look very closely at a portion of DNA and find methylated histones, you would

be looking at a region of inactive chromatin.

The progesterone receptor (PR) is a steroid hormone receptor and transcription factor. The protein SRC-1, which does not bind DNA by itself, can bind to PR and increase expression of genes regulated by PR. Based on this information, SRC-1 is best described as a(n)

coactivator.

DNA methylation is the only known natural modification of DNA. It affects

cytosine bases.

Although the specific mechanism of RNA interference has not been fully defined, it involves

double stranded RNA interference with mRNA.

Transcriptional control-proteins increase the rate of transcription by binding to

enhancer sequences within the DNA.

Through control of gene expression, a bacterial cell responds to changing __________ conditions.

environmental

A defining characteristic of eukaryotic organisms is that they

have their transcription occurring in the nucleus and translation in the cytoplasm.

The most common DNA-binding motif is the

helix-turn-helix.

One of the DNA-binding motifs in many eukaryotic organisms that contains a nearly identical sequence of 60 amino acids is known as the

homeodomain.

The maintenance of a constant environment in a cell is called __________.

homeostasis

The main form of glucose repression in the lac operon is

inducer exclusion.

The enzyme beta-galactosidase acts on lactose to form galactose. In turn, the presence of galactose leads to expression of the enzymes responsible for the metabolism of galactose. In this case, lactose is serving as a carbon source and as a(n)

inducer.

The lactose analog isopropyl-beta-D-thio-galactoside (IPTG) is often used to regulate gene expression systems in bacteria. IPTG does not act as a substrate for beta-galactosidase, but can bind to, and inactivate, the repressor. In this case, IPTG serves as a(n)

inducer.

If you were given a bacterial strain with a mutation in the promoter region of the trp operon the most likely effect would be

interference with RNA polymerase binding.

The proteins necessary for the use of lactose in E. coli are collectively called the

lac operon.

Small RNAs can regulate gene expression. One type, called micro RNA (miRNA), acts by binding directly to

mRNA to prevent translation.

The hallmark of multicellular organisms is their ability to

maintain homeostasis.

You have been asked to design a synthetic DNA motif, able to bind transcriptional regulatory proteins. The location on this motif that you will design for protein binding is the

major groove of the DNA double helix.

Vertebrate cells possess a protein that binds to clusters of 5-methylcytosine and ensures the gene will stay in the "off" position. This control of gene regulation is a result of

methylation.

The enzyme dicer chops dsRNA molecules into small pieces of

miRNA and siRNA.

In some organisms, the primary function of a gene in a cell is to participate in regulating the body as a whole rather than responding to the cell's immediate environment. These organisms would be

multicellular.

Histones that are tightly wound by DNA and are the basic unit of chromatin are called

nucleosomes.

In vertebrates, DNA methylation - the addition of a methyl group to DNA nucleotides - ensures that

once a gene is turned off, it will remain off.

A site of negative genetic regulation where binding by repressor blocks transcription is the

operator.

A cluster of functionally-related genes that are regulated together and encoded into a single mRNA molecule is called a(n)

operon.

You are working to identify enhancer regions of a particular gene. The best place to look is

primarily upstream of the promoter, possibly some distance away.

A site at the 5' end of a gene where RNA polymerase attaches to initiate transcription is called a(n).

promoter.

In multicellular organisms, the mechanism most directly responsible for directing development and maintaining homeostasis is gene

regulation.

The basic tool of genetic regulation is the ability of certain proteins to bind to specific

regulatory DNA sequences.

The p300/CBP (CREB-binding protein) proteins are histone acetyltransferases that help regulate the transcription of many genes. Based on this information you can conclude that these proteins

remodel chromatin.

A protein that regulates transcription by binding to the operator is known as the

repressor.

Enhancers are the binding sites for the

specific transcription factors.

Eukaryotic cell mRNA transcripts can remain in the cell for hours because they are

stable

The DNA-binding proteins of almost all regulatory proteins use one of a small set of shapes that enable them to fit into the DNA major groove. These shapes are called

structural motifs.

Certain proteins can bind to specific DNA regulatory sequences by entering

the major groove of the DNA and reading the nucleotide base pairs.

As a microbiologist you have been asked to investigate the regulation of a novel gene in a bacterial species. Given what is known about bacteria, the logical place to begin your investigation is

transcriptional regulation.

Production of the iron-storing protein ferritin is regulated by aconitase, which binds to a 30-nucleotide sequence at the beginning of the ferritin mRNA and interferes with ribosome binding. Aconitase must be a

translation repressor protein.

You work for a pharmaceutical company that designs small RNAs, used to control expression of disease genes . The primary focus area of your research should be

translational repression.

You lead a research team challenged with the task of creating a regulatory protein able to shut off transcription of a particular gene. You focus your design around a binding site called an operator that is associated with the promotor. The physical location of the operator most likely to affect transcription would be

upstream of the gene promoter. B. downstream of the gene promoter.

You are studying the function of a recently identified gene in C. elegans. You perform genetic screens for several months in an attempt to isolate loss-of-function gene mutations, but your efforts are unsuccessful. Your advisor suggests you try another approach to eliminate gene function. The best technique to accomplish this goal would be

use RNA interference to prevent mRNA translation.