Chapter 16 & 17

Which organism has the simplest transcription regulation? A plant, such as A. thaliana A bacterium, such as E. coli A nematode, such as C. elegans A mammal, such as H. sapiens

A bacterium, such as E. coli

One of the first miRNA that was discovered by scientists involves the lin-4 gene of C. elegans. The product of the lin-4 gene is which of the following? A miRNA that acts as a ribozyme and degrades the lin-14 mRNA A miRNA that inhibits the translation of the lin-14 gene because it is complementary to lin-14 mRNA A small protein that inhibits the mRNA production from the lin-14 gene.

A miRNA that inhibits the translation of the lin-14 gene because it is complementary to lin-14 mRNA

________ is the inducer of the lac operon.

Allolactose

Calcitonin and CGRP are two hormones produced from the same transcript due to which of the following? RNA editing RNA interference Nuclear export Alternative splicing

Alternative splicing

The production of different mature mRNAs from the same primary transcript is called which of the following? Intron editing Alternative splicing Alternative maturation RNA editing

Alternative splicing

How can proteins interact with DNA and recognize DNA sequences without unwinding the DNA double helix? By interacting with the major groove of the double helix By reading the pattern of methylation in DNA By interacting with histone proteins By reading the histone code By interacting with the minor groove of the double helix

By interacting with the major groove of the double helix

How can enhancers stimulate transcription despite being located far away from the genes they regulate? The enhancer can interact with promoter through long chains of chromatin proteins. DNA can bend and form a loop bringing the enhancer close to the promoter. Activators bind enhancers and then slide along DNA until they reach the promoter.

DNA can bend and form a loop bringing the enhancer close to the promoter.

As lactose levels fall in E. coli, what happens to the concentrations of allolactose? Decrease Remain the same Increase

Decrease

As lactose levels fall in E. coli, what happens to the concentrations of allolactose? Increase Remain the same Decrease

Decrease

siRNAs arise from which of the following structures? Double-stranded RNA Double-stranded DNA Single-stranded RNA Single-stranded DNA

Double-stranded RNA

Which of the following describes the control of the initiation of transcription? Either positive or negative Always negative Always positive

Either positive or negative

DNA sequences that are necessary for high levels of transcription and can act independently of position or orientation are called which of the following? Mediators Enhancers Promoters Activators

Enhancers

Chromatin undergoes an _______ alteration when the alteration persists in the absence of a stimulus and is passed to daughter cells during cell division.

Epigenetic

Which of the following statements about mRNAs in prokaryotes and eukaryotes is true? Eukaryotic mRNAs are typically much more stable than prokaryotic mRNAs. Prokaryotic mRNAs are typically much more stable than eukaryotic mRNAs. Most eukaryotic and prokaryotic mRNAs have similar half-lives.

Eukaryotic mRNAs are typically much more stable than prokaryotic mRNAs.

Regulatory proteins stimulate transcription by which of the following methods? Degrading and removing proteins that are attached to DNA and are in the way of RNA polymerase Facilitating the binding of RNA polymerase to the promoter Increasing the rate of RNA synthesis by RNA polymerase several orders of magnitude

Facilitating the binding of RNA polymerase to the promoter

Transcription factors that are necessary for the assembly of a transcription apparatus and recruitment of RNA polymerase II to a promoter are called which of the following? Specific transcription factors General transcription factors Nonspecific transcription factors

General transcription factors

Which of the following is a mechanism by which glucose represses the expression of the lac operon? Glucose binds to the lac operon and enhances its ability to block expression of the lac operon. Glucose binds to CAP, which enables it to prevent transcription of the lac operon. Glucose binds directly to the DNA and prevents the binding of RNA polymerase. Glucose inhibits the production of cAMP, thereby preventing the activation of the lac operon.

Glucose inhibits the production of cAMP, thereby preventing the activation of the lac operon.

All of the following are examples of post-transcriptional regulation in eukaryotes, except which of the following? Histone modification RNA interference RNA editing Alternative splicing

Histone modification

In eukaryotes, gene regulation is geared toward maintaining which of the following? Homeostasis Constant levels of all necessary enzyme throughout the life of a cell Reason: The levels of enzymes in eukaryotic cells are constantly adjusted - this is what allows the cell to participate in the maintenance of overall homeostasis. The function of the nucleus Constant levels of oxygen

Homeostasis

Which of the following are reasons why eukaryotes have a more complex gene regulation than prokaryotes? Prokaryotic chromosomes are circular, while eukaryotic chromosomes are linear. In eukaryotes, transcription occurs in the nucleus, while translation occurs in the cytoplasm. Eukaryotic DNA is organized into chromatin. Eukaryotes generally have longer DNA molecules than prokaryotes.

In eukaryotes, transcription occurs in the nucleus, while translation occurs in the cytoplasm. Eukaryotic DNA is organized into chromatin.

Which of the following statements about the different kinds of mRNAs in eukaryotic cells is true? In general, mRNAs for regulatory proteins have much longer half-lives. Virtually all mRNAs in a eukaryotic cells have a similar half-life and are very stable. In general, mRNAs for regulatory proteins have much shorter half-lives.

In general, mRNAs for regulatory proteins have much shorter half-lives.

High levels of DNA methylation correlate with which of the following? Multiple select question. Areas of significant mutations Inactive genes Active genes Allele-specific gene expression seen in genomic imprinting

Inactive genes Allele-specific gene expression seen in genomic imprinting

Which of the following are modifications that have been documented during RNA editing? Insertion of uracil residues Excision of several codons from the mRNA Replacement of uracil residues with thymine residues Chemical modification of bases that change their base-pairing properties

Insertion of uracil residues Chemical modification of bases that change their base-pairing properties

n the absence of tryptophan, which of the following describes the trp repressor? It cannot bind its operator. It can bind its operator.

It cannot bind its operator.

Select ways in which the loss of the poly-A tail of an mRNA promotes its quick degradation. Loss of the tail leads to degradation by 3' to 5' RNA exonucleases. Loss of the tail stimulates ubiquitination of the mRNA which tags it for degradation. Loss of the tail stimulates cap removal, which leads to degradation by 5' to 3' RNA exonucleases. Loss of the tail leads to degradation by RNA endonucleases.

Loss of the tail leads to degradation by 3' to 5' RNA exonucleases. Loss of the tail stimulates cap removal, which leads to degradation by 5' to 3' RNA exonucleases.

In the following list, choose all that are components of the eukaryotic transcription complex. Mediators and co-activators Specific transcription factors RNA polymerase II mRNA transcript Histones General transcription factors

Mediators and co-activators Specific transcription factors RNA polymerase II General transcription factors

Regulatory proteins are proteins that do which of the following? Modulate the rate at which RNA polymerase is adding nucleotides to the growing RNA molecule Modulate the ability of RNA polymerase to bind to the promoter Modulate the ability of RNA polymerase to unwind the DNA double helix

Modulate the ability of RNA polymerase to bind to the promoter

Where is the trp repressor gene located? Between the promoter and the operator Immediately before the genes for tryptophan synthesis Outside the trp operon Immediately following the genes for tryptophan synthesis.

Outside the trp operon

The RNA interference pathway in this type of organism is much more complex than that of animals. Plants Yeasts Protists Bacteria

Plants

Repressors are which type of molecules? Phospholipids Proteins Lipids Nucleic acids Carbohydrates

Proteins

The serotonin (5-HT) receptor in the human brain has 12 different isoforms produced by which of the following? Gene re-arrangement Alternative splicing Post-translational editing RNA editing

RNA editing

Which of the following are forms of post-transcriptional regulation in eukaryotes? RNA interference mRNA degradation rate Histone acetylation RNA editing Alternative splicing DNA methylation

RNA interference mRNA degradation rate RNA editing Alternative splicing

Activators enhance the the binding of which of the following enzymes to the promoter region of the DNA? DNA polymerase Ligase Helicase RNA polymerase

RNA polymerase

vWhen the lac repressor is bound to the operator region of DNA which of the following enzymes is prevented from binding to the promoter region? Helicase RNA polymerase DNA polymerase Catalase

RNA polymerase

Which of the following are the requirements for gene transcription to be initiated in prokaryotic and eukaryotic cells? RNA polymerase must be capable of binding the promoter. The DNA double helix has to be partially unwound by special enzymes, so that RNA synthesis can begin A transcription stimulating complex involving RNA polymerase and many other proteins must form. RNA polymerase must have access to the DNA double helix.

RNA polymerase must be capable of binding the promoter. RNA polymerase must have access to the DNA double helix.

In order for a gene to be transcribed, _________ polymerase must have access to the DNA double helix and be able to bind the gene's ________.

RNA; promoter

Which of the following are considered parts of the lac operon? Enhancer gene located downstream from the operon Regulatory regions of the operon (promoter and operator) Repressor gene (lacI) Genes required for utilization of lactose The gene encoding the CAP protein

Regulatory regions of the operon (promoter and operator) Repressor gene (lacI) Genes required for utilization of lactose

Which type of eukaryotic transcription factors can increase the level of transcription in certain cells in response to signals? Signaling transcription factors Specific transcription factors General transcription factors Response transcription factors

Specific transcription factors

Which of the following describes the regulation of the lac and trp operons in bacteria? Only the lac operon is negatively controlled by a repressor protein. The lac and trp operons are negatively controlled by a repressor protein. The lac and trp operons are positively controlled by a repressor protein. Only the trp operon is negatively controlled by a repressor protein.

The lac and trp operons are negatively controlled by a repressor protein.

Choose all ways in which glucose represses the utilization of lactose in glucose repression. Glucose binds to the repressor instead of allolactose. The presence of glucose leads to low level of cAMP. The presence of glucose inhibits the transport of lactose in the cell (inducer exclusion). Glucose directly binds to the operator affecting how strongly RNA polymerase binds to the promoter.

The presence of glucose leads to low level of cAMP. The presence of glucose inhibits the transport of lactose in the cell (inducer exclusion).

An operon is derepressed when which of the following occurs? The repressor and corepressor are bound to the operator An inducer is bound to the repressor The repressor alone cannot bind to the operator The repressor alone is bound to the operator

The repressor alone cannot bind to the operator

What is the function of the genes that are expressed in the lac operon of E. coli? The repression of lactose The utilization of lactose The synthesis of lactose

The utilization of lactose

What is the function of a promoter in eukaryotic cells? They are directly recognized by RNA polymerase II. They are binding sites for general transcription factors which recruit RNA polymerase in order to initiate transcription. They are binding sites for specific transcription factors which recruit RNA polymerase in order to initiate transcription.

They are binding sites for general transcription factors which recruit RNA polymerase in order to initiate transcription.

Which of the following describes miRNAs and siRNAs? They are small RNA molecules that are involved in posttranscriptional gene expression control. They are small RNA molecules that act as specific transcription factors. They are small RNA molecules that are act as mediators during transcription. They are small RNA molecules that are involved in transcriptional gene expression control.

They are small RNA molecules that are involved in posttranscriptional gene expression control.

How do mediators and co-activators act? They first bind a transcription factor and then bind another part of the transcription apparatus. They bind an enhancer and recruit specific transcription factors to that enhancer. They bind a specific transcription factor altering its conformation so that it can now bind an enhancer.

They first bind a transcription factor and then bind another part of the transcription apparatus.

What effect does the presence of general transcription factors have on the basal rate of transcription? They decrease the basal rate of transcription. They increase the basal rate of transcription. They have no effect on the basal rate of transcription.

They have no effect on the basal rate of transcription.

Small RNAs may have evolved for which of the following functions? To protect the genome To assist in translational modification To help mRNA leave the nucleus

To protect the genome

In all cells, gene regulation most commonly happens at which level? mRNA maturation Transcription termination Transcription initiation Translation initiation

Transcription initiation

MicroRNAs and short-interfering RNAs regulate gene expression at what level? Transcription Post-translational regulation of protein function Translation RNA processing

Translation

Select ways in which the initiation of translation can be regulated. Translation factors can be modified. tRNAs can be targeted for degradation Translation repressor proteins can block translation initiation. Ribosome degrading proteins can prevent ribosomes from assembling.

Translation factors can be modified. Translation repressor proteins can block translation initiation.

True or false: Even though we have little evidence, it is believed that the transport of mRNAs out of the nucleus is a potential site of gene regulation.

True

The trp operon in E. coli contains information for the making of proteins responsible for the synthesis of _________

Tryptophan

Where does a cell get the double-stranded RNA needed to produce siRNAs. Viral infection From the cell itself Bacterial infection

Viral infection From the cell itself

Which of the following statements accurately describes glucose repression in bacteria. When both glucose and lactose are present, the lac operon is induced, but bacteria will only use the glucose. When both glucose and lactose are present, the lac operon is induced and bacteria will not use the glucose. When both glucose and lactose are present, the lac operon is not induced and bacteria will only use the glucose.

When both glucose and lactose are present, the lac operon is not induced and bacteria will only use the glucose.

Chromatin can be altered in a number of ways, such as histone modification and DNA methylation. When are such alterations considered to be epigenetic (choose all that apply)? When they persist in the absence of the initiation stimulus When they only affect one chromosome (paternal or maternal) When they are inherited through cell division When they lead to inactivation of DNA

When they persist in the absence of the initiation stimulus When they are inherited through cell division

Select the true statements about the control of the trp operon. When tryptophan levels are low, the repressor is inactive and the trp operon is transcribed. When tryptophan levels are low, the corepressor (tryptophan) binds to the repressor and transcription of the trp operon is blocked. When tryptophan levels are high, the corepressor (tryptophan) binds to the repressor and transcription of the trp operon is blocked. When tryptophan levels are high, the repressor is inactive and the trp operon is transcribed.

When tryptophan levels are low, the repressor is inactive and the trp operon is transcribed. When tryptophan levels are high, the corepressor (tryptophan) binds to the repressor and transcription of the trp operon is blocked.

When is the trp operon derepressed? When the expression of the trpI gene is inhibited When tryptophan levels fall and the repressor can no longer bind the operator When tryptophan levels are high and the repressor is activated by its co-repressor When tryptophan levels are high and the repressor is inactivated

When tryptophan levels fall and the repressor can no longer bind the operator

__________ (use the acronym) is the gene that initiates the inactivation process of one X-chromosome in mammalian females.

Xist

What is the order of the lac genes following the operator? Y, A, Z Z, A, Y A, Y, Z Z, Y, A

Z, Y, A

The lac repressor binds to the lac operon when lactose is (present/absent) and the trp repressor binds to the trp operon when tryptophan is (present/absent). absent; present absent; absent present; present present; absent

absent; present

_________ are allosteric proteins that can bind to DNA and stimulate the initiation of transcription.

activators

The CAP protein, which plays an important role in the function of the lac operon, can bind which small molecule? Lactose Allolactose cAMP ATP

cAMP

In eukaryotes, DNA is organized into ____ , which considerably complicates DNA-protein interactions during gene regulation.

chromatin

The production of a functional miRNA begins in the _______ nucleus and ends in the of the cell.

cytoplasm

The production of a functional miRNA begins in the nucleus and ends in the _____ of the cell.

cytoplasm

When an operon is expressed because the repressor protein alone can't bind to the operator, the operon is said to be ________ . In contrast, an operon can be _______ when an effector molecule inactivates the repressor.

depressed; induced

Chemical modification of bases in the RNA to change their base-pairing properties (deamination of cytosine to uracil and deamination of adenine to inosine) are examples of RNA ____

editing

THe 5-HT serotonin receptor in humans can exist in 12 isoforms. These isoforms are produced through RNA ________

editing

Prokaryotic gene regulation is geared toward responding to changes in the ________ ; in multicellular eukaryotes, gene regulation is critical for directing ________ and maintaining ________

environment, development, homeostasis

Gene regulation allows bacteria to survive in response to __________ changes, such as the availability of specific nutrients.

environmental

Changes in gene expression in prokaryotes are tightly linked to changes in the environment. For that reason almost all of the changes are temporary, i.e., the changes are reversed after a certain period of time, regardless of the environmental conditions irreversible fully reversible, depending on environmental conditions

fully reversible, depending on environmental conditions

Most multicellular organisms execute complex developmental programs that ensure the production of functioning organisms; these developmental programs are heavily dependent on coordinated changes in ____ _______

gene expression

Eukaryotic promoters are binding sites for ______ transcription factors.

general

Eukaryotic promoters are binding sites for ________ transcription factors.

general

In fission yeast, plants and Drosophila, small RNAs and the RNA silencing pathways have been implicated in the formation of ______

heterochromatin

In E. coli, the lac operon is (induced/repressed) in the presence of lactose, and the trp operon is (induced/repressed) in the presence of tryptophan. induced; repressed repressed; induced repressed; repressed induced; induced

induced; repressed

In bacteria ________ occurs when certain enzymes for a certain pathway are produced in response to a substrate.

induction

Proteins can recognize specific base pair sequences in DNA without unwinding the double helix by interacting with the _________ _______ of the helix.

major groove

Co-activators and ___________ act by binding transcription factors and then binding another part of the transcription apparatus.

mediators

DNA _____ was the first modification of chromosome structure shown to act epigenetically.

methylation

Which of the following tend to repress genes different from their origin?

miRNA

Which of the following tend to repress genes different from their origin? siRNA miRNA tRNA mRNA

miRNA

Which of the following RNA molecules act in post-transcriptional gene regulation? tRNA miRNA RISC siRNA rRNA

miRNA siRNA

miRNAs were first discovered in a group of organisms called ______

nematodes

The repressor of the lac operon binds to the region called the ______

operator

Repressors are proteins that bind to regulatory sites on DNA called ________. These prevent transcription.

operators

A(n) _______ is a cluster of genes that are part of a single transcription unit that is under the control of a single promoter. Listen to the complete question

operons

In __________ cells regulation allows rapid response to changes in the environment; in ___________ cells, gene regulation is critical for maintaining homeostasis.

prokaryotic; eukaryotic

When glucose levels are high, the level of cAMP in E. coli cells is ________

reduced

Glucose _______ occurs when bacterial cells are grown in the presence of glucose and lactose. In the presence of both sugars, bacteria will preferentially use the glucose before using the lactose.

repression

In bacteria _______occurs when the organisms capable of making biosynthetic enzymes do not produce them.

repression

Which of the following are used experimentally to turn off the expression of genes?

siRNAs

In Drosophila, sex determination involves a series of alternative ______ events, which differ in males and females.

splicing

In both prokaryotes and eukaryotes, gene regulation most commonly occurs at the level of _________ initiation.

transcription

RNA polymerase II, together with all of the general and specific transcription factors and associated mediators and co-activators, form the _______ eukaryotic complex.

transcription

In some cases, the initiation of translation is regulated when _______ ________ proteins bind to the beginning of an mRNA so that the mRNA cannot attach to the ribosome.

translation repressor

miRNAs were discovered during studies of the lin-4 gene in C. elegans; this gene encodes for which of the following? A short polypeptide (22 amino acids) Two small RNAs (22 and 61 nucleotides, respectively) A small RNA (61 nucleotides) and a small polypeptide (22 amino acids) Two short poplypeptides (22 and 61 amino acids, respectively)

two small rnas (22 and 61 nucleotides, respectively)