Bio - Gene regulation

Where is bicoid mRNA translated? Sperm cells Nurse cells Follicle cells Fertilized egg

Fertilized egg

The tryptophan operon is a repressible operon that is turned off only when glucose is present in the growth medium. permanently turned on. turned on only when glucose is present in the growth medium. turned off whenever tryptophan is added to the growth medium. turned on only when tryptophan is present in the growth medium.

turned off whenever tryptophan is added to the growth medium.

Which statement(s) about repressible operons is/are correct? Select all that apply. A repressible operon is on unless a corepressor is present. In a repressible operon, the repressor is synthesized in an active form. Repressible enzymes generally function in anabolic pathways.

A repressible operon is on unless a corepressor is present. Repressible enzymes generally function in anabolic pathways.

Which body part develops in regions with a low concentration of Bicoid protein? Thorax Head

Abdomen

Which of the following regulatory elements is not composed of DNA sequences? Promoter-proximal elements Enhancers Activators Silencers

Activators

_____ bind(s) to DNA enhancer regions. RNA polymerase Promoters Introns Activators Exons

Activators

Which of the following enzymes converts ATP to cAMP? b-galactosidase Galactoside permease Adenylyl cyclase ATP synthase

Adenylyl cyclase

Which of the following statements best defines the term operon? An operon is a region of DNA that consists of a single gene regulated by more than one promoter. An operon is a region of DNA that codes for sugar-metabolizing enzymes. An operon is a region of RNA that consists of the coding regions of more than one gene. An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter.

An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter.

Which of the following is not a body segment of the fruit fly embryo? Thorax Abdomen Head Antenna

Antenna

Which of the following regulatory DNA sequences might be located thousands of nucleotides away from the transcription start site of a gene? TATA box Promoter Promoter-proximal element Enhancer

Enhancer

True or false? One possible way to alter chromatin structure such that genes could be transcribed would be to make histone proteins more positively charged. True False

False

True or false? Regulatory and basal transcription factors regulate transcription by binding to the promoter. True False

False

True or false? The mechanism by which glucose inhibits expression of the lac structural genes is known as catabolite stimulation, whereas the mechanism by which lactose stimulates expression of the lac structural genes is known as allosteric regulation. True False

False

What is allosteric regulation? In allosteric regulation, genes are expressed constitutively. In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity. In allosteric regulation, a gene is turned on by an activator protein. In allosteric regulation, a gene is turned off by a repressor protein.

In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity.

Which of the following statements about the DNA in one of your brain cells is true? It is the same as the DNA in one of your heart cells. Many genes are grouped into operon-like clusters. Most of the DNA codes for protein. Each gene lies immediately adjacent to an enhancer. The majority of genes are likely to be transcribed.

It is the same as the DNA in one of your heart cells.

The operon model of the regulation of gene expression in bacteria was proposed by _____. Watson and Crick Franklin Darwin Jacob and Monod Mendel

Jacob and Monod

Under which conditions are the lac structural genes expressed most efficiently? High glucose, no lactose No glucose, no lactose No glucose, high lactose High glucose, high lactose

No glucose, high lactose

Which of the following terms describes the DNA-protein complexes that look like beads on a string? Nucleosome 30-nanometer fiber Chromatin Histones

Nucleosome

Which of the following statements about a gene that shows maternal effect inheritance is true? Offspring will have a mutant phenotype if the father has a mutant genotype. Offspring will show a mutant phenotype if the mother has a mutant genotype. Embryonic cells transcribe the gene. Offspring will always show a mutant phenotype if they have a mutant genotype.

Offspring will show a mutant phenotype if the mother has a mutant genotype.

All your cells contain proto-oncogenes, which can change into cancer-causing genes. Why do cells possess such potential time bombs? Proto-oncogenes are genetic junk that has not yet been eliminated by natural selection. Proto-oncogenes protect cells from infection by cancer-causing viruses. Cells produce proto-oncogenes as a by-product of mitosis. Proto-oncogenes are unavoidable environmental carcinogens. Proto-oncogenes are necessary for the normal control of cell growth and division.

Proto-oncogenes are necessary for the normal control of cell growth and division.

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells? Proto-oncogenes are genetic "junk." Cells produce proto-oncogenes as they age. Proto-oncogenes are mutant versions of normal genes. Proto-oncogenes normally help regulate cell division. Proto-oncogenes first arose from viral infections.

Proto-oncogenes normally help regulate cell division.

What molecule binds to promoters in bacteria and transcribes the coding regions of the genes? DNA ligase A nucleotide RNA polymerase DNA polymerase

RNA polymerase

Which of the following events in transcription initiation likely occurs last? RNA polymerase binds to the promoter of the gene. Basal transcription factors form a basal transcription complex. Regulatory transcription factors bind to enhancers. TBP is recruited to the promoter.

RNA polymerase binds to the promoter of the gene.

Which of the following statements about the Bicoid protein is true? The Bicoid protein is diffused evenly throughout the fertilized egg. The Bicoid protein is a regulatory transcription factor. The Bicoid protein establishes the dorsal-ventral body axis. The Bicoid protein is a cytoplasmic determinant.

The Bicoid protein is a regulatory transcription factor.

If bicoid mRNA is injected at the anterior end of an egg from a bicoid mutant mother, what would the phenotype of the resulting larva be? The larva would have a head at each pole of its body. The larva would be normal with one head at the anterior pole. The larva would have two heads, one at the anterior pole and one in the middle of its body. The larva would be normal with one head at the posterior pole.

The larva would be normal with one head at the anterior pole.

What happens to the expression of the lacI gene if lactose is not available in the cell? There is no change—the lacI gene is constitutively expressed. The lacI gene turns on. The lacI gene turns off. The lacI gene increases its rate of transcription.

There is no change—the lacI gene is constitutively expressed.

What is the function of the lacZ gene? This gene encodes an enzyme, galactoside permease, which transports lactose into the cell. This gene encodes an enzyme, b-galactosidase, that cleaves lactose into two glucose molecules. This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose. This gene encodes the repressor of the lac operon.

This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose.

True or False? Pattern formation refers to events that organize embryonic cells in space True False

True

Why is the lac operon said to be an inducible operon? When activated, the lac operon induces the production of lactose-digesting enzymes. When allolactose is present, it induces the inactivation of the lac repressor. When allolactose is present, it induces repression of gene expression. When allolactose is present, it induces the activation of the lac repressor. When activated, the lac operon induces repression of gene expression.

When allolactose is present, it induces the inactivation of the lac repressor.

Which of the following would be most likely to lead to cancer? hyperactivity of both a proto-oncogene and a tumor-suppressor gene hyperactivity of a proto-oncogene and activation of a tumor-suppressor gene failure of a proto-oncogene to produce a protein and amplification of a tumor-suppressor gene amplification of a proto-oncogene and inactivation of a tumor-suppressor gene failure of both a proto-oncogene and a tumor-suppressor gene to produce proteins

amplification of a proto-oncogene and inactivation of a tumor-suppressor gene

The role of a metabolite that controls a repressible operon is to bind to the repressor protein and activate it. bind to the repressor protein and inactivate it. bind to the operator region and block the attachment of RNA polymerase to the promoter. bind to the promoter region and decrease the affinity of RNA polymerase for the promoter. increase the production of inactive repressor proteins.

bind to the repressor protein and activate it.

What is the event that IMMEDIATELY follows the last event of this animation? unbending of the DNA and the release of RNA polymerase from the promoter binding of the activators to enhancers transcription binding of mRNA to the smaller ribosomal subunit binding of RNA polymerase to the promoter

binding of RNA polymerase to the promoter

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator? overproduction of catabolite activator protein (CAP) buildup of a substrate for the pathway controlled by the operon continuous transcription of the operon's genes irreversible binding of the repressor to the promoter reduced transcription of the operon's genes

continuous transcription of the operon's genes

A lack of which molecule would result in the cell's inability to "turn off" genes? inducer ubiquitin corepressor promoter operon

corepressor

Muscle cells differ from nerve cells mainly because they use different genetic codes. have different chromosomes. have unique ribosomes. contain different genes. express different genes.

express different genes.

DNA methylation is a mechanism used by eukaryotes to do what? inactivate genes terminate transcription cause apoptosis facilitate the binding of DNA to intermediate filaments increase the rate of transcription

inactivate genes

Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator? promoter repressor inducer ubiquitin corepressor

inducer

Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene is transcribed in the early embryo. normally leads to formation of head structures. normally leads to formation of tail structures. leads to programmed cell death. is a protein present in all head structures.

normally leads to formation of head structures.

In the presence of a regulatory protein the lac operon is _____. transcribed not transcribed transcribed at a faster than usual rate is turned on either transcribed or not transcribed

not transcribed

Which of these is NOT a component of the lac operon? lactose-utilization genes only promoter only regulatory gene only operator only promoter and operator

regulatory gene only

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then the repressor is active in the absence of the amino acid. the enzymes produced are called inducible enzymes. the amino acid acts as a corepressor. the amino acid turns on transcription of the operon. the amino acid inactivates the repressor.

the amino acid acts as a corepressor.

The lactose operon is likely to be transcribed when the cyclic AMP levels are low. there is glucose but no lactose in the cell. the cAMP level is high and the lactose level is low. there is more glucose in the cell than lactose. the cyclic AMP and lactose levels are both high within the cell.

the cyclic AMP and lactose levels are both high within the cell.

Regulatory proteins bind to _____. the operator the lactose-utilization genes the regulatory gene RNA polymerase transcription factors

the operator

Cell differentiation always involves the movement of cells. the selective loss of certain genes from the genome. the cell's sensitivity to environmental cues, such as light or heat. the transcription of the myoD gene. the production of tissue-specific proteins, such as muscle actin.

the production of tissue-specific proteins, such as muscle actin.

Which of the following is an example of post-transcriptional control of gene expression? the addition of methyl groups to cytosine bases of DNA the binding of transcription factors to a promoter the folding of DNA to form heterochromatin gene amplification contributing to cancer the removal of introns and alternative splicing of exons

the removal of introns and alternative splicing of exons

The functioning of enhancers is an example of a post-transcriptional mechanism to regulate mRNA. transcriptional control of gene expression. post-translational control that activates certain proteins. the stimulation of translation by initiation factors. a eukaryotic equivalent of prokaryotic promoter functioning.

transcriptional control of gene expression.