BCH 369 EXAM 3 QUESTIONS WITH
ALL REVISED ANSWERS
Which of the following is(are) used to determine to which family a virus is categorized? -
Answer-Viruses can be categorized by:
whether its genome is composed of single-stranded DNA.
whether its genome is composed of double-stranded DNA.
whether it has a membrane envelope.
whether its genome is composed of single-stranded RNA.
Suppose you want to design a drug to fight a virus. Which of the following would be
good choices?
(Select all that apply.) - Answer-A molecule that attacks one of the specific protein
spikes on the virus.
An example of this could be an antibody that binds to the spike protein. Another choice
is a designer molecule that binds to the spike protein or the cell surface attachment site
and interferes with the spike protein-cell surface interaction.
A molecule that inhibits a key viral enzyme.
An example enzyme target is reverse transcriptase for retroviruses. Another example
target would be the enzymes involved in repackaging the virus.
Retroviruses have an RNA genome that must be reverse-transcribed in the host to DNA
by viral reverse transcriptase. The DNA copy of the RNA genome must recombine with
the host's DNA genome in order for the viral genes to be expressed. - Answer-.
T Cells and B cells - Answer-Acquired Immunity
Dendritic cells and Macrophages - Answer-Second line innate immunity
Tears and skin - Answer-First line innate immunity
Which of the following are components of the system for acquired immunity? - Answer-
Helper T cells and Killer T cells
Describe how the cells of the acquired-immunity system develop so that they do not
recognize self-antigens but do recognize foreign antigens. - Answer-B cells and T cells
express cell-surface receptors that are used to control the proliferation of these cells. If
they express receptors for self-antigens, the cells are targeted for removal and undergo
apoptosis. If they express receptors for no antigen, the cells will die by neglect. If, on the
other hand, they express receptors for foreign antigens, the cells will be activated for
proliferation and action against the source of the foreign antigens.
Which of the following are characteristics shown by cancer cells? - Answer-Cancer cells
are effectively immortal.
,Cancer cells can grow in the presence of "stop growing" signals.
They can be metastatic, with the ability to migrate within the body to establish new loci
of growth.
Cancer cells are unspecialized and do not develop into cells of a specific type.
How does HIV confound the human immune system? - Answer-The gp120 protein
undergoes a conformational change when it binds to a T cell.
The outer membrane of HIV contains sugars that are very similar to those found on
most of its host's cells.
HIV binds a cell protein that blocks the antiviral action of natural killer cells.
Which form of immunity is characteristic of vertebrates only? - Answer-adaptive
immunity
From the following, select different techniques that might restore p53 to a cell lacking it.
- Answer-through administering drugs that inhibit the transcription of molecules that
inhibit p53.
through neutralizing molecules that naturally inhibit p53.
through administering drugs that stimulate the transcription of p53.
Through gene therapy, giving the patient functional copies of the p53 gene.
1 Which of the following types of RNA undergo post-transcriptional modifications?
a. mRNA
b. rRNA
c. tRNA
d. All of the above
e. None of the above - Answer-d
2 Which of these terms does not describe the DNA strand used to direct RNA
synthesis?
a. Template strand
b. Coding strand
c. Antisense strand
d. Negative or "−" strand
e. All these terms describe the DNA strand used to direct RNA synthesis - Answer-b
3 RNA synthesis begins at the base in the DNA sequence designated by the following
number:
a. +1 (plus one)
b. 0 (zero)
c. −1 (minus one)
d. −10 region (minus ten)
e. It varies between genes. - Answer-a
,4 Initiation of RNA biosynthesis involves
a. recognition of the promoter region by the α subunit of RNA polymerase
b. conversion of the closed-promoter complex to the open-promoter complex
c. binding of one of the α subunits of RNA polymerase to each strand of DNA
d. incorporation of four pyrimidine nucleotides in succession - Answer-b
5 The majority of protein synthesis occurs in the
a. nucleus
b. mitochondrion
c. cytoplasm
d. nucleolus - Answer-c
6 At which position on the mRNA is the wobble base of the triplet codon?
a. first position (5' letter)
b. second position
c. third position (3' letter)
d. the wobble base can be at any position - Answer-c
, 7 An aminoacyl-adenylate contains
a. an ester bond
b. an acid anhydride bond
c. an amide bond
d. an ether bond - Answer-b
8 After peptide bond formation takes place, what step is necessary for continuation of
protein synthesis?
a. binding of uncharged tRNA to the ribosome
b. binding of EF−Tu
c. binding of EF−Ts
d. translocation of the ribosome - Answer-d
9 The application of gel electrophoresis (PAGE) in DNA sequencing
a. is nonexistent because DNA fragments differ widely in charge.
b. depends on separation of similar charge/mass ratio on the basis of size.
c. depends on separation of identical size on the basis of charge/mass ratio.
d. is nonexistent because DNA fragments have no net charge. - Answer-b
10 SyBr green and SyBr gold were developed because
a. ethidium bromide is not sensitive enough for modern research
b. they allow faster electrophoretic separations of DNA
c. they fluoresce with RNA as well as DNA, while ethidium bromide does not
d. ethidium bromide is carcinogenic - Answer-d
11 Antibiotic-resistance genes in vectors are often used as selectable markers.
a. True
b. False - Answer-a
12 What is the function of protein spikes on a virus?
a. They protect the genome.
b. They are involved with incorporation of the genome into that of host (lysogeny).
c. They transcribe the RNA genome into a DNA copy.
d. They help the virus attach to the host. - Answer-d
13 Antibodies are the most variable protein sequences in the human body.
a. True
b. False - Answer-a
14 The term antibody is essentially interchangeable with
a. immunoglobulin.
b. reverse transcriptase.
c. allergen.
d. vaccine. - Answer-a
15 Which type of interactions predominate for sequence-specific DNA-binding proteins?
ALL REVISED ANSWERS
Which of the following is(are) used to determine to which family a virus is categorized? -
Answer-Viruses can be categorized by:
whether its genome is composed of single-stranded DNA.
whether its genome is composed of double-stranded DNA.
whether it has a membrane envelope.
whether its genome is composed of single-stranded RNA.
Suppose you want to design a drug to fight a virus. Which of the following would be
good choices?
(Select all that apply.) - Answer-A molecule that attacks one of the specific protein
spikes on the virus.
An example of this could be an antibody that binds to the spike protein. Another choice
is a designer molecule that binds to the spike protein or the cell surface attachment site
and interferes with the spike protein-cell surface interaction.
A molecule that inhibits a key viral enzyme.
An example enzyme target is reverse transcriptase for retroviruses. Another example
target would be the enzymes involved in repackaging the virus.
Retroviruses have an RNA genome that must be reverse-transcribed in the host to DNA
by viral reverse transcriptase. The DNA copy of the RNA genome must recombine with
the host's DNA genome in order for the viral genes to be expressed. - Answer-.
T Cells and B cells - Answer-Acquired Immunity
Dendritic cells and Macrophages - Answer-Second line innate immunity
Tears and skin - Answer-First line innate immunity
Which of the following are components of the system for acquired immunity? - Answer-
Helper T cells and Killer T cells
Describe how the cells of the acquired-immunity system develop so that they do not
recognize self-antigens but do recognize foreign antigens. - Answer-B cells and T cells
express cell-surface receptors that are used to control the proliferation of these cells. If
they express receptors for self-antigens, the cells are targeted for removal and undergo
apoptosis. If they express receptors for no antigen, the cells will die by neglect. If, on the
other hand, they express receptors for foreign antigens, the cells will be activated for
proliferation and action against the source of the foreign antigens.
Which of the following are characteristics shown by cancer cells? - Answer-Cancer cells
are effectively immortal.
,Cancer cells can grow in the presence of "stop growing" signals.
They can be metastatic, with the ability to migrate within the body to establish new loci
of growth.
Cancer cells are unspecialized and do not develop into cells of a specific type.
How does HIV confound the human immune system? - Answer-The gp120 protein
undergoes a conformational change when it binds to a T cell.
The outer membrane of HIV contains sugars that are very similar to those found on
most of its host's cells.
HIV binds a cell protein that blocks the antiviral action of natural killer cells.
Which form of immunity is characteristic of vertebrates only? - Answer-adaptive
immunity
From the following, select different techniques that might restore p53 to a cell lacking it.
- Answer-through administering drugs that inhibit the transcription of molecules that
inhibit p53.
through neutralizing molecules that naturally inhibit p53.
through administering drugs that stimulate the transcription of p53.
Through gene therapy, giving the patient functional copies of the p53 gene.
1 Which of the following types of RNA undergo post-transcriptional modifications?
a. mRNA
b. rRNA
c. tRNA
d. All of the above
e. None of the above - Answer-d
2 Which of these terms does not describe the DNA strand used to direct RNA
synthesis?
a. Template strand
b. Coding strand
c. Antisense strand
d. Negative or "−" strand
e. All these terms describe the DNA strand used to direct RNA synthesis - Answer-b
3 RNA synthesis begins at the base in the DNA sequence designated by the following
number:
a. +1 (plus one)
b. 0 (zero)
c. −1 (minus one)
d. −10 region (minus ten)
e. It varies between genes. - Answer-a
,4 Initiation of RNA biosynthesis involves
a. recognition of the promoter region by the α subunit of RNA polymerase
b. conversion of the closed-promoter complex to the open-promoter complex
c. binding of one of the α subunits of RNA polymerase to each strand of DNA
d. incorporation of four pyrimidine nucleotides in succession - Answer-b
5 The majority of protein synthesis occurs in the
a. nucleus
b. mitochondrion
c. cytoplasm
d. nucleolus - Answer-c
6 At which position on the mRNA is the wobble base of the triplet codon?
a. first position (5' letter)
b. second position
c. third position (3' letter)
d. the wobble base can be at any position - Answer-c
, 7 An aminoacyl-adenylate contains
a. an ester bond
b. an acid anhydride bond
c. an amide bond
d. an ether bond - Answer-b
8 After peptide bond formation takes place, what step is necessary for continuation of
protein synthesis?
a. binding of uncharged tRNA to the ribosome
b. binding of EF−Tu
c. binding of EF−Ts
d. translocation of the ribosome - Answer-d
9 The application of gel electrophoresis (PAGE) in DNA sequencing
a. is nonexistent because DNA fragments differ widely in charge.
b. depends on separation of similar charge/mass ratio on the basis of size.
c. depends on separation of identical size on the basis of charge/mass ratio.
d. is nonexistent because DNA fragments have no net charge. - Answer-b
10 SyBr green and SyBr gold were developed because
a. ethidium bromide is not sensitive enough for modern research
b. they allow faster electrophoretic separations of DNA
c. they fluoresce with RNA as well as DNA, while ethidium bromide does not
d. ethidium bromide is carcinogenic - Answer-d
11 Antibiotic-resistance genes in vectors are often used as selectable markers.
a. True
b. False - Answer-a
12 What is the function of protein spikes on a virus?
a. They protect the genome.
b. They are involved with incorporation of the genome into that of host (lysogeny).
c. They transcribe the RNA genome into a DNA copy.
d. They help the virus attach to the host. - Answer-d
13 Antibodies are the most variable protein sequences in the human body.
a. True
b. False - Answer-a
14 The term antibody is essentially interchangeable with
a. immunoglobulin.
b. reverse transcriptase.
c. allergen.
d. vaccine. - Answer-a
15 Which type of interactions predominate for sequence-specific DNA-binding proteins?
