Deck 14: Control of Gene Expression

Question 1

Which of the following is not true? Organisms turn genes on and off

A) depending on the function of the cell.
B) in response to environmental changes.
C) to cause certain developmental changes.
D) to switch from prokaryotic to eukaryotic status.

Answer 1

D

Question 2

All cells in an organism contain a full copy of that organism's DNA. Your ears do not produce digestive enzymes because

A) stomach cells have extra DNA.
B) ear cells have nonfunctional DNA.
C) some DNA is deleted from cells where it isn't needed.
D) different genes are expressed in different parts of an organism.

Answer 2

D

Question 3

Which of the following does not correctly state a difference between prokaryotic and eukaryotic DNA organization?

A) Prokaryotic DNA groups genes with related functions together whereas eukaryotic DNA does not.
B) Prokaryotic DNA has few noncoding regions, unlike eukaryotic DNA.
C) Eukaryotic DNA is usually arranged more simply than prokaryotic DNA.
D) Eukaryotic DNA contains more spacer regions than prokaryotic DNA.

Answer 3

C

Question 4

Would you expect the presence of spacer DNA to increase or decrease the frequency of linkage between genes?

A) decrease it, because the spacer DNA is removed from the genome before transcription
B) decrease it, because the spacer DNA increases the probability of crossing-over between genes
C) increase it, because the spacer DNA is tightly connected to the genes on both sides
D) increase it, because the spacer DNA encourages the insertion of transposons into the DNA

Question 5

The genes that act as the "master switches" for gene cascades are

A) housekeeping genes.
B) homeotic genes.
C) genes in introns.
D) spacer genes.

Question 6

How can a cell contain DNA molecules that are much longer than the cell?

A) The cell expands to fit the DNA inside.
B) DNA not used by that cell is deleted.
C) DNA is very narrow and tightly packed.
D) RNA copies allow DNA to dissolve.

Question 7

Housekeeping genes

A) prevent operators from expressing genes.
B) prevent repressors from binding.
C) are expressed by most cells in the body.
D) break down a cell's DNA.

Question 8

Which is not true of homeotic genes?

A) They are similar in very different organisms.
B) They control the expression of other genes.
C) They cause every cell in an organism to behave identically.
D) They are evolutionarily old.

Question 9

Noncoding DNA

A) codes for RNA but not proteins.
B) codes for introns and spacer DNA.
C) includes spacer DNA and transposons.
D) includes spacer DNA and introns.

Question 10

During an organism's development, sets of gene products interact with each other in a process known as

A) a gene cascade.
B) a homeotic cascade.
C) a DNA chip.
D) housekeeping.

Question 11

One level of DNA packing involves the DNA being wound around

A) histone proteins.
B) an RNA molecule.
C) cytoplasmic organelles.
D) translation enzymes.

Question 12

Development is controlled by

A) spacer sequences.
B) different homeotic genes in different organisms.
C) similar homeotic genes in different animals.
D) repressor proteins.

Question 13

Why might it not be surprising to learn that human DNA contains bacterial genes?

A) Eukaryotes were formed when ancient prokaryotic cells engulfed each other.
B) Bacterial genes are present in the nuclei of all known organisms.
C) Bacteria insert their genomes into host cells in order to reproduce.
D) Human cells engulf bacteria as a source of raw material for DNA synthesis.

Question 14

Why do organisms have the ability to change gene expression?

A) Being able to change gene expression prevents an organism from wasting energy and resources on protein production.
B) The environment is constantly changing and an organism must be able to react to that change.
C) Changing gene expression ensures that exactly the right proteins are available when they are needed.
D) all of the above

Question 15

In plants, transposons are often the cause of variegation (the formation of white stripes of cells on a green leaf). Which of the following explains why a transposon might have this effect?

A) The white cells are dead cells. When a transposon moves from one chromosome to another, it kills its host cell.
B) When a bacterium infects a plant cell, the plant cell begins producing bacterial proteins rather than plant proteins.
C) When a transposon "jumps" into the gene involved in the production of the green pigment in a plant, the gene no longer functions so the cells are all white.
D) When a transposon enters a cell, it inhibits the translation of all proteins.

Question 16

In condensed chromosomes, histone spools

A) lie between introns in the DNA molecule.
B) contain most of the spacer genes in a cell.
C) have DNA wrapped around them.
D) are sites where active transcription takes place.

Question 17

Most of a human's DNA is

A) single-stranded.
B) noncoding.
C) regulatory sequences.
D) prokaryotic.

Question 18

Which of the following statements is not true of eukaryotic DNA?

A) It is located in each cell's cytoplasm.
B) It contains transposons.
C) It has more genes than prokaryotic DNA has.
D) It contains many noncoding sequences.

Question 19

Which of the following choices might cause an intron to be read as part of a coding gene?

A) a frameshift mutation
B) the binding of the mRNA codon to the tRNA anticodon
C) a change in the coils of the DNA packing system
D) a rapid breakdown of mRNA molecules

Question 20

In interphase, each chromosome in a cell consists of

A) four DNA molecules.
B) a paired DNA/RNA molecule.
C) one DNA molecule.
D) an RNA/enzyme complex.

Question 21

The enzymes involved in ATP synthesis in the mitochondria are likely to be encoded by _________ genes.

A) regulatory
B) homeotic
C) housekeeping
D) transposon

Question 22

An operator is a sequence of DNA whose function it is to

A) bind to the chromosome to prevent replication.
B) bind to the chromosome to prevent gene expression.
C) control the transcription of a gene or group of genes.
D) control the translation of a gene or group of genes.

Question 23

In this figure, are the genes that encode the enzymes needed to make tryptophan on or off?

A) The genes are on because the genes involved in tryptophan production are housekeeping genes
B) The genes are on because the complex of tryptophan and repressor protein allow RNA polymerase to bind to the promoter.
C) The genes are off because the complex of tryptophan and repressor protein prevent RNA polymerase from interacting with regulatory DNA.
D) The genes are off because when tryptophan is plentiful in the environment, RNA polymerase is not made.

Question 24

RNA interference has been proposed as a treatment for cancer. Which of the following accurately explains how this treatment could work?

A) RNA injected into cancerous cells would prevent transcription of cancer-causing genes.
B) Normal (not mutated) mRNA for DNA polymerase would be inserted into the genome of tumor cells.
C) Tumors would be injected with small pieces of double stranded RNAs that recognize the mRNA of genes that promote cell division.
D) RNAi would bind to tubulin, preventing the formation of the spindle apparatus.

Question 25

The most common way for cells to control gene expression is by controlling

A) translation.
B) transcription.
C) spacer DNA frequency.
D) mutation.

Question 26

The DNA sequences of human beings and chimpanzees are approximately 99 percent alike. What might explain the seemingly large differences that exist between these two closely related organisms?

A) Chimpanzees use RNA as the heritable genetic material, so DNA sequences are not important.
B) Chimpanzee DNA does not have the introns found in human DNA.
C) Humans are eukaryotic and chimpanzees are prokaryotic.
D) Different patterns of gene expression regulate the two organisms' genomes.

Question 27

During interphase, the genes that are most tightly packed

A) are being expressed more rapidly than loosely packed genes.
B) are not being expressed, because the proteins needed for transcription can't reach them.
C) are more responsive to proteins necessary for transcription.
D) have greater access to the promoters that are packed with them.

Question 28

The figure below illustrates two levels of DNA packing in a eukaryotic cell.
In which level is transcription most likely to occur?

A) Conformation A, because the tight coiling brings regulatory DNA sequences closer together.
B) Conformation A, because tight coiling only occurs during cell division which is when transcription occurs.
C) Conformation B, because RNA polymerase can only access regulatory DNA when chromosomes are not condensed.
D) Conformation B, because in this conformation, the DNA is completely separated from histones that bind to regulatory DNA sequences preventing transcription.

Question 29

A cell has a repressor protein for substance A. If substance A is present in sufficient quantities,

A) the repressor protein will be bound to RNA polymerase.
B) the repressor protein will be bound to substance A.
C) substance A will be bound to the operator.
D) a repressor protein-substance A complex will be bound to RNA polymerase.

Question 30

Which of the following features of DNA is important to the function of a gene chip?

A) DNA contains both introns and exons.
B) The bases in DNA are complementary to the bases in RNA.
C) Eukaryotic DNA contains mostly noncoding sequences.
D) DNA can be labeled with fluorescent dyes.

Question 31

This table shows which of these four genes are on or off in three different cell types.
Why is the expression of the rRNA gene so different from the expression of the other genes in the table?

A) rRNA is required for the proper functioning of all cells, but the products of the other genes are only essential to the function of one cell type.
B) rRNA is easier to produce than the products of the other genes.
C) The rRNA gene is found in the genomes of all three cell types, but the other genes are only found in the genomes of their specific cell type.
D) rRNA is needed at all stages of the cell cycle, but the products of the other genes are only needed during cell division.

Question 32

Which of the following are removed from mRNA after transcription?

A) introns
B) transposons
C) spacer DNA
D) exons

Question 33

DNA chips are

A) expressed in every cell of an organism.
B) excised from RNA molecules.
C) unneeded bits of DNA.
D) useful for monitoring gene expression.

Question 34

In E. coli when tryptophan is present in the environment,

A) the tryptophan operator will break down tryptophan.
B) the tryptophan-repressor protein will be unable to bind to the tryptophan operator.
C) tryptophan will bind to a repressor protein.
D) the tryptophan-repressor protein will be unable to bind to tryptophan.

Question 35

A repressor protein

A) prevents DNA replication.
B) prevents the expression of certain genes.
C) is the same as an operator sequence.
D) helps RNA begin transcription.

Question 36

Which is not a way that cells can control gene expression?

A) Tightly packed DNA is not expressed.
B) Cells break down DNA that codes for unexpressed proteins.
C) Cells regulate the breakdown of mRNA.
D) Cells can inhibit translation.

Question 37

Which of the following is directly involved in the regulation of transcription?

A) RNA polymerase
B) tRNA
C) DNA polymerase
D) repressor protein

Question 38

Proteins found in the blood respond to blood vessel damage by clumping together forming a clot that physically blocks the hole in the vessel and preventing further blood loss. If clotting proteins were active all the time, they would create clots throughout your circulatory system. Which of the following would be the most efficient way for the body to regulate the expression of the proteins involved in clotting?

A) Produce and store the clotting protein in an inactive form. When the protein is needed, use another protein to activate the clotting protein.
B) Use a repressor protein to keep clotting genes turned off until they are needed.
C) Tightly package the genes for clotting proteins so that they cannot be accessed by RNA polymerase unless needed.
D) Constantly make the clotting proteins, but then break them down instantly after translation if they are not needed.

Question 39

Which of the following can be described as housekeeper genes?

A) genes that code for processing arabinose in E. coli
B) genes that code for producing chemicals that transmit nerve signals
C) genes that code for making muscle proteins
D) genes that code for making rRNA

Question 40

The fact that the DNA sequences of most homeotic genes are very similar in a wide variety of animals suggests that

A) homeotic genes are in a location of the genome that rarely undergoes mutation.
B) homeotic genes probably evolved millions of years ago in the first animals.
C) mutations in homeotic genes have little impact on an organism.
D) homeotic genes play a minor role in the process of development.

Question 41

A repressor protein binds to the operator of a group of genes to turn ______ [on or off?] their gene expression.

Question 42

A _______ is a DNA sequence that is capable of moving from one position to another.

Question 43

Regulatory proteins bind to regulatory ___ sequences.

Question 44

In eukaryotes, some genes with related functions are found on different chromosomes.

Question 45

At any given time, most of the genes in the genome of an organism are actively undergoing gene expression.

Question 46

The genome of a prokaryote rarely contains ______________ DNA sequences that do not encode genes or undergo transcription.

Question 47

DNA is tightly packed around protein spools known as ______________.

Question 48

The amount of DNA in a prokaryotic cell is _______ than the amount of DNA in a eukaryotic cell.

Question 49

The _______ of eukaryotes vary greatly in size from 12 million base pairs in some to more than a trillion base pairs in other.

Question 50

Eukaryotic genes do not contain transposons.

Question 51

Gene _______ is the synthesis of a gene's protein or RNA product.

Question 52

A change in an organism's environment generally results in a change in ________ ________, leading to the production of different types of proteins.

Question 53

Transposons can move both within a chromosome and from one chromosome to another.

Question 54

Specific types of proteins can attach to long-lived mRNA molecules to prevent their ___________ when the cell does not need their protein product.

Question 55

_______ DNA consists of stretches of nucleotides that separate genes.

Question 56

If an ear develops where an eye should be, the cause is most likely a mutation in a ________ gene.

Question 57

Organisms control when, where, and how much of each gene product is made.

Question 58

_______ genes are master switches that control the expression of other genes.

Question 59

DNA is _______ [more or less?] tightly packaged during interphase when most gene expression occurs.

Question 60

The benefit of putting a group of related genes under the control of a single _____________ is that the activation of this single regulatory sequence can lead to the production of all the proteins needed to respond to an environmental change.

Question 61

One method eukaryotes use to control gene expression is to break down a gene's protein product.

Question 62

The 220 different cell types in the human body each contain all of the same DNA found in every other cell type.

Question 63

Why is regulating transcription the main way the cells control gene expression?

Question 64

Once a gene has been translated, no further regulation of gene expression is possible.

Question 65

If the gene of a repressor protein were to be mutated such that its protein no longer functioned, the genes it regulated would not be transcribed.

Question 66

Once a gene is turned on, it cannot be turned off.