Biology Chapter 18 MCQ

If a mutation alters a maternal effect gene in a female Drosophila zygote, which of the following is most likely to occur?

All of her offspring will show the mutant phenotype, regardless of their genotype

If a researcher moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following results would be most likely?

Beta galactosidase will not be produced

The cAMP receptor protein (CRP) is said to be responsible for positive regulation of the lac operon because

CRP bound to the CRP-binding site stimulates the transcription of the lac operon

Much of the human genome does not code for proteins. Which of the following types of DNA are found in these regions of the genome?

DNA that is transcribed into several kinds of small RNAs with biological function

Which of the following conclusions is consistent with the fact that plants can be cloned from somatic cells?

Differentiated cells retain all the genes of the zygote

Which of the following best explains why a neuron and a pancreatic cell isolated from the same individual contain different sets of proteins?

Each cell type contains different regulatory proteins and, therefore, they express different proteins

Which of the following statements correctly describes the primary difference between enhancers and proximal control elements?

Enhancers are located considerable distances from the promoter; proximal control elements are close to the promoter

Which of the following mechanisms is commonly used to coordinate the expression of multiple, related genes in eukaryotic cells?

Groups of genes that are expressed together have specific combinations of control elements

Which of the following processes is the best way to determine whether alternative splicing of a given gene occurs?

Isolate mRNA from the given gene and compare the sequences

A mutation in E. coli results in a molecule known as a "super-repressor" because the operon is permanently repressed. Which of the following describes the most likely effect of the mutation on the repressor protein?

It cannot bind to the inducer

Which of the following describes the normal function of the p53 gene product?

It inhibits the cell cycle

Under which condition do high levels of transcription of structural genes occur in an inducible operon?

It starts when the pathway's substrate is present

Which of the following explains why introducing the MyoD protein into a fat cell causes that cell to become a muscle cell but adding it to a neuron will have no effect?

Muscle-specific gene expression requires a protein that neurons do not make

Which of the following processes destroys RNA molecules if they have a sequence complementary to an introduced double-stranded RNA?

RNA interference

For a repressible operon to be transcribed, which of the following conditions must occur?

RNA polymerase must bind to the promoter, and the repressor must be inactive

Which of the following conditions is most likely to result in transcription of the lac operon?

The cAMP and lactose levels are both high within the cell

A cell is considered to be differentiated if it has which of the following characteristics?

The cell produces proteins specific to a particular cell type

Which of the following predictions about the survival of a lactose intolerant E. coli cell is most likely correct?

The cell will survive if the environment has sufficient glucose

In wildtype Drosophila embryos, the bicoid mRNA is localized to the anterior end of the embryo. If bicoid mRNA was injected into the embryo's posterior end as well, which of the following developmental events would occur?

The embryo would show anterior structures at both ends of the embryo

If a researcher moves the operator to the far end of the operon, which of the following processes would likely occur when the cell is exposed to lactose?

The genes of the lac operon will be transcribed continuously

If a researcher moves the repressor gene (lacI) and its promoter, to a position at some several thousand base pairs away from its normal position, which of the following describes the most likely effect on the lac operon?

The lac operon will function normally

According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon?

The lac operon would be transcribed continuously

Which of the following is the most likely phenotypes of a yeast mutant that contains histones that are resistant to acetylation?

The mutant will show decreased levels of gene expression

A researcher introduced many copies of a double-stranded RNA into a culture of mammalian cells and used a fluorescent probe to follow it. Later she finds that the introduced strands separate into single-stranded RNAs and she hypothesizes that the molecules is acting as an miRNA. Which of the following pieces of evidence would support her claim?

The rate of accumulation of the polypeptide encoded by the target mRNA is reduced

Which of the following characterizes BRCA1 and BRCA2 as tumor-suppressor genes?

Their normal products participate in repair of DNA damage

Cytoplasmic determinants are best described as having which of the following characteristics?

They are maternal substances in the egg that influence the course of early development

Which of the following describes how steroid hormones regulate gene expression?

They bind to intracellular receptors and alter transcription of specific genes

Which of the following functions are characteristic of general transcription factors in eukaryotes?

They bind to other proteins or to the TATA box

Which of the following statements correctly describes a characteristic of tumor-suppressor genes?

They encode proteins that help prevent uncontrolled cell growth

Which of the following describes the role typical proto-oncogenes have when they are expressed in cells that are not cancerous?

They stimulate normal cell growth & division

Which of the following changes in conditions results in an increase in cAMP receptor protein (CRP) mediated initiation of transcription?

a decrease in glucose and an increase in cAMP

Which of the following statements best describes the characteristics of siRNA?

a double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

Which of the following types of mutation would convert a proto-oncogene into an oncogene?

a mutation that greatly increases the amount of the proto-oncogene protein

Prokaryote's ability to regulate patterns of gene expression most likely promotes the organism's survival by

allowing an organism to adjust to changes in environmental conditions

Assays analyzing transcriptional control of gene expression focus on which of the following characteristics?

amount of the mRNA generated

A researcher introduced many copies of a double-stranded RNA into a culture of mammalian cells and used a fluorescent probe to follow it. She found that the introduced strands separated; one strand degraded and the other single-stranded RNA remained. The remaining strand is able to do which of the following?

bind to complementary regions of target mRNAs

How does breakdown of glucose inhibit transcription of the lac operon?

by reducing the levels of intracellular cAMP

A rise in extracellular glucose results in which of the following changes at the lac operon?

cAMP receptor protein (CRP) detaches from the lac promoter

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?

colorectal only

If a mutation deactivated a regulatory gene of a repressible operon in an E. coli cell which of the following describes the most likely outcome?

continuous transcription of the structural gene controlled by that regulator

Which of the following methods are used by eukaryotes to control gene expression but are not used by bacteria?

control of both RNA splicing and chromatin remodeling

Which of the following is a molecule that helps to "turn off" the expression of genes in a cell?

corepressor

Which of the following results is most likely to occur if acetylation of histone tails in the chromatin of embryonic cells is increased?

decreased chromatin condensation

DNA methylation and histone acetylation are examples of which of the following processes?

epigenetic phenomena

Forms of the Ras protein found in tumors usually cause which of the following events to occur?

excessive cell division

In colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated?

genes involved in control of the cell cycle

Mutations in which of the following genes result in transformations in the identity of entire body parts?

homeotic genes

If the DNA of a mammalian promoter region experiences increased methylation on cytosine (C) which of the following results is most likely to occur?

inactivation of the gene

When taken up by a cell, which of the following molecules binds to a repressor so that the repressor no longer binds to an operator?

inducer

Which of the following molecules binds with a repressor to alter its conformation and therefore affect its function?

inducer

Which of the following characteristics of gene expression allows bacteria to quickly change protein synthesis patterns in response to environmental changes?

mRNAs that are produced are short-lived and degraded within a few minutes of being synthesized

The product of the bicoid gene in Drosophila is responsible for determining which of the following embryonic features or structures during development?

orientation of the anterior-posterior axis

Which of the following types of RNA is responsible for helping to reestablish methylation patterns during gamete formation?

piRNA

Which of the following molecules is a protein produced by a regulatory gene?

repressor

Gene expression is often assayed by measuring the level of mRNA produced from a gene. Which of the following levels of the control of gene expression can by analyzed by this type of assay?

transcriptional control

Under what conditions does the trp repressor block transcription of the trp operon?

when the repressor binds to tryptophan