Chapter 18 Part 5

Front 1

Given the damage caused by UV, the kind of gene affected in those with XP is one whose product is involved with
A) mending of double-strand breaks in the DNA backbone.
B) breakage of cross-strand covalent bonds.
C) the ability to excise single-strand damage and replace it.
D) the removal of double-strand damaged areas.
E) causing affected skin cells to undergo apoptosis.

Back 1

the ability to excise single-strand damage and replace it.

Front 2

Two children are born from the same parents. Child one inherits a predisposition to retinoblastoma (one of the mutations) and child two does not. However, both children develop the retinoblastoma. Which of the following would you expect?
A) an earlier age of onset in child one
B) a history of exposure to mutagens in child one but not in child two
C) a more severe cancer in child one
D) increased levels of apoptosis in both children
E) decreased levels of DNA repair in child one

Back 2

an earlier age of onset in child one

Front 3

In colorectal cancer, several genes must be mutated in order to make a cell a cancer cell, supporting Knudsen's hypothesis. Which of the following kinds of genes would you expect to be mutated?
A) genes coding for enzymes that act in the colon
B) genes involved in control of the cell cycle
C) genes that are especially susceptible to mutation
D) the same genes that Knudsen identified as associated with retinoblastoma
E) the genes of the bacteria that are abundant in the colon

Back 3

genes involved in control of the cell cycle

Front 4

Knudsen and colleagues also noted that persons with hereditary retinoblastoma that had been treated successfully lived on but then had a higher frequency of developing osteosarcomas (bone cancers) later in life. This provided further evidence of their theory because
A) osteosarcoma cells express the same genes as retinal cells.
B) p53 gene mutations are common to both tumors.
C) both kinds of cancer involve overproliferation of cells.
D) one of the mutations involved in retinoblastoma is also one of the changes involved in osteosarcoma.
E) retinoblastoma is a prerequisite for the formation of osteosarcoma later in life.

Back 4

one of the mutations involved in retinoblastoma is also one of the changes involved in osteosarcoma.

Front 5

One of the human leukemias, called CML (chronic myelogenous leukemia), is associated with a chromosomal translocation between chromosomes 9 and 22 in somatic cells of bone marrow. Which of the following allows CML to provide further evidence of this multistep nature of cancer?
A) CML usually occurs in more elderly persons (late age of onset).
B) The resulting chromosome 22 is abnormally short; it is then known as the Philadelphia chromosome.
C) The translocation requires breaks in both chromosomes 9 and 22, followed by fusion between the reciprocal pieces.
D) CML involves a proto-oncogene known as abl.
E) CML can usually be treated by chemotherapy.

Back 5

The translocation requires breaks in both chromosomes 9 and 22, followed by fusion between the reciprocal pieces.

Front 6

In areas of the world in which malaria is endemic, notably in sub-Saharan Africa, EBV can cause Burkitt's lymphoma in children, which is usually associated with large tumors of the jaw. Which of the following is consistent with these findings?
A) EBV infection makes the malarial parasite able to produce lymphoma.
B) Malaria's strain on the immune system makes EBV infection worse.
C) Malaria occurs more frequently in those infected with EBV.
D) Malarial response of the immune system prevents an individual from making EBV antibodies.
E) A cell infected with the malarial parasite is more resistant to the virus.

Back 6

Malarial response of the immune system prevents an individual from making EBV antibodies.

Front 7

In a different part of the world, namely in parts of southeast Asia, the same virus is associated with a different kind of cancer of the throat. Which of the following is most probable?
A) Viral infection is correlated with a different immunological reaction.
B) The virus infects the people via different routes.
C) The virus only infects the elderly.
D) The virus mutates more frequently in the Asian population.
E) Malaria is also found in this region.

Back 7

Viral infection is correlated with a different immunological reaction.

Front 8

A very rare human allele of a gene called XLP, or X-linked lymphoproliferative syndrome, causes a small number of people from many different parts of the world to get cancer following even childhood exposure to EBV. Given the previous information, what might be going on?
A) The people must have previously had malaria.
B) Their ancestors must be from sub-Saharan Africa or southeast Asia.
C) They must be unable to mount an immune response to EBV.
D) They must have severe combined immune deficiency (SCID).
E) Their whole immune system must be overreplicating.

Back 8

They must be unable to mount an immune response to EBV.

Front 9

What must characterize the XLP population?
A) They must have severe immunological problems starting at birth.
B) They must all be males with affected male relatives.
C) They must all be males with affected female relatives.
D) They must all inherit this syndrome from their fathers.
E) They must live in sub-Saharan Africa.

Back 9

They must all be males with affected female relatives.

Front 10

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

Back 10

the amino acid acts as a corepressor.

Front 11

Muscle cells differ from nerve cells mainly because they
A) express different genes.
B) contain different genes.
C) use different genetic codes.
D) have unique ribosomes.
E) have different chromosomes.

Back 11

express different genes.

Front 12

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

Back 12

transcriptional control of gene expression.

Front 13

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

Back 13

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

Front 14

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

Back 14

the removal of introns and alternative splicing of exons

Front 15

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

Back 15

continuous transcription of the operon's genes

Front 16

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
A) is transcribed in the early embryo.
B) normally leads to formation of tail structures.
C) normally leads to formation of head structures.
D) is a protein present in all head structures.
E) leads to programmed cell death.

Back 16

normally leads to formation of head structures.

Front 17

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

Back 17

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