Molecular Biology Exam questions
and answers graded A+
If a DNA fragment contains 210 base pairs, which of the following is true?
a. The DNA length is about 99A
b. The DNA fragment has about 420 H bonds
c. The diameter of the DNA helix is 22A
d. The DNA fragment has about 20 helix turns - ANS✅✅d. The DNA fragment has about 20 helix
turns
In a piece of DNA, which of the following is true?
a. The ratio of A, T, C, and G is equal
b. The ratio of T must be different from C
c. The ratio of G is always equal to C
d. All of the above are true - ANS✅✅c. The ratio of G is always equal to C
Which of the following statements is false?
a. The two strands of a DNA helix are identical in base number
b. The two strands of a DNA helix are identical in length
c. The two strands of a DNA helix are identical in hydrogen bond numbers
d. The two strands of a DNA helix are identical in direction - ANS✅✅d. The two strands of a DNA
helix are identical in direction
The following proportions exist in DNA: C+A = T+G
a. Yes, this is always true for regular DNA molecules
b. Nope, its actually A=G, C=T
c. Untrue, you lying varmint! C>G, A>T
d. None of the above - ANS✅✅a. Yes, this is always true for regular DNA molecules
The minor groove of a DNA double helix
a. Presents a wide variety of chemical groups to other proteins
,b. Is not much different from the major groove
c. Is distinctive in prokaryotes but not in eukaryotes
d. Is the site of histone/DNA interactions - ANS✅✅d. Is the site of histone/DNA interactions
In a nucleotide, such as dATP the phosphate is attached to the ___ carbon of deoxyribose
a. 5'
b. 3'
c. 2'
d. 1' - ANS✅✅a. 5'
The chemical bond that links the nucleotides one by one in a single DNA string is
a. H bond
b. Peptide bond
c. Phosphodiester bond 5' with 3' phosphate
d. Phosphodiester bond 3' with 5' phosphate - ANS✅✅c. Phosphodiester bond 5' with 3'
phosphate
Core histones
a. Contain n-terminal tails that can be chemically modified
b. Are small and rich in R and L
c. Are very similar in amino acid sequence among different organisms from humans to plants
d. All - ANS✅✅c. Are very similar in amino acid sequence among different organisms from humans
to plants
The histones are
a. Highly conserved that they are identical among all organisms
b. All over 50 kDa in size
c. Highly conserved that there are only a few amino acid differences between plants and humans
d. Composed of different aa in addition to the 20 common aa - ANS✅✅c. Highly conserved that
there are only a few amino acid differences between plants and humans
Which of the following is true?
,a. DNA is usually in A form
b. DNA is usually in the B form
c. DNA is usually in the Z form
d. DNA can take any of the three forms in the cell - ANS✅✅b. DNA is usually in the B form
DNA denature and re-nature (annealing) is not important for
a. Southern blot
b. Northern blot
c. Western blot
d. All of the above - ANS✅✅c. Western blot
When DNA fragments with identical sequence form different helices, which of the follow is true?
a. The A form is the longest
b. The Z form is a right handed helix
c. The A form is thicker than the B form
d. The B form is thicker than the A form - ANS✅✅c. The A form is thicker than the B form
Which of the following statements is false?
a. RNA has U
b. RNA has ribose
c. RNA has more diversified secondary structure
d. RNA cannot form double helix structure at all - ANS✅✅d. RNA cannot form double helix
structure at all
Which of the following characteristics of RNA does not contribute to RNA's unique feature?
a. RNA contains U instead of T
b. RNA has an extra -OH group
c. RNA can allow triple base pairing
d. RNA contains phosphate group - ANS✅✅d. RNA contains phosphate group
The H2A and H2B
, a. Bind with linker DNA
b. Form tetramers
c. Form dimers
d. Are the same protein in two different forms - ANS✅✅c. Form dimers
The DNA fragment wrapping around the histone core of a nucleosome
a. Is about 50 bp
b. Is about 147 bp
c. Varies in length in different cells
d. Varies in length substantially among different species - ANS✅✅b. Is about 147 bp
Which of the following is false?
a. The number of H2A and H2B are always the same in regular nucleosome
b. The number of H3 and H4 are always the same in the regular nucleosome
c. The number of H3 is always more than H2A in regular nucleosome
d. The number of H3 is always the same as H2A in a regular nucleosome - ANS✅✅c. The number of
H3 is always more than H2A in regular nucleosome
If not associated with nucleosome, H2A and H2B are presented as __ in the cell.
a. Dimers
b. Monomers
c. Trimers
d. Tetramers - ANS✅✅a. Dimers
Which of the following is true?
a. Restriction cut the DNA from either 5' or 3' ends
b. Restriction that recognize 4 bp cut the DNA less frequently than those that recognize 6 bp
c. Restriction cut all the DNA with the right recognition sites
d. Restriction always generate sticky ends - ANS✅✅c. Restriction cut all the DNA with the right
recognition sites
Some of the DNA ends are called sticky ends because
and answers graded A+
If a DNA fragment contains 210 base pairs, which of the following is true?
a. The DNA length is about 99A
b. The DNA fragment has about 420 H bonds
c. The diameter of the DNA helix is 22A
d. The DNA fragment has about 20 helix turns - ANS✅✅d. The DNA fragment has about 20 helix
turns
In a piece of DNA, which of the following is true?
a. The ratio of A, T, C, and G is equal
b. The ratio of T must be different from C
c. The ratio of G is always equal to C
d. All of the above are true - ANS✅✅c. The ratio of G is always equal to C
Which of the following statements is false?
a. The two strands of a DNA helix are identical in base number
b. The two strands of a DNA helix are identical in length
c. The two strands of a DNA helix are identical in hydrogen bond numbers
d. The two strands of a DNA helix are identical in direction - ANS✅✅d. The two strands of a DNA
helix are identical in direction
The following proportions exist in DNA: C+A = T+G
a. Yes, this is always true for regular DNA molecules
b. Nope, its actually A=G, C=T
c. Untrue, you lying varmint! C>G, A>T
d. None of the above - ANS✅✅a. Yes, this is always true for regular DNA molecules
The minor groove of a DNA double helix
a. Presents a wide variety of chemical groups to other proteins
,b. Is not much different from the major groove
c. Is distinctive in prokaryotes but not in eukaryotes
d. Is the site of histone/DNA interactions - ANS✅✅d. Is the site of histone/DNA interactions
In a nucleotide, such as dATP the phosphate is attached to the ___ carbon of deoxyribose
a. 5'
b. 3'
c. 2'
d. 1' - ANS✅✅a. 5'
The chemical bond that links the nucleotides one by one in a single DNA string is
a. H bond
b. Peptide bond
c. Phosphodiester bond 5' with 3' phosphate
d. Phosphodiester bond 3' with 5' phosphate - ANS✅✅c. Phosphodiester bond 5' with 3'
phosphate
Core histones
a. Contain n-terminal tails that can be chemically modified
b. Are small and rich in R and L
c. Are very similar in amino acid sequence among different organisms from humans to plants
d. All - ANS✅✅c. Are very similar in amino acid sequence among different organisms from humans
to plants
The histones are
a. Highly conserved that they are identical among all organisms
b. All over 50 kDa in size
c. Highly conserved that there are only a few amino acid differences between plants and humans
d. Composed of different aa in addition to the 20 common aa - ANS✅✅c. Highly conserved that
there are only a few amino acid differences between plants and humans
Which of the following is true?
,a. DNA is usually in A form
b. DNA is usually in the B form
c. DNA is usually in the Z form
d. DNA can take any of the three forms in the cell - ANS✅✅b. DNA is usually in the B form
DNA denature and re-nature (annealing) is not important for
a. Southern blot
b. Northern blot
c. Western blot
d. All of the above - ANS✅✅c. Western blot
When DNA fragments with identical sequence form different helices, which of the follow is true?
a. The A form is the longest
b. The Z form is a right handed helix
c. The A form is thicker than the B form
d. The B form is thicker than the A form - ANS✅✅c. The A form is thicker than the B form
Which of the following statements is false?
a. RNA has U
b. RNA has ribose
c. RNA has more diversified secondary structure
d. RNA cannot form double helix structure at all - ANS✅✅d. RNA cannot form double helix
structure at all
Which of the following characteristics of RNA does not contribute to RNA's unique feature?
a. RNA contains U instead of T
b. RNA has an extra -OH group
c. RNA can allow triple base pairing
d. RNA contains phosphate group - ANS✅✅d. RNA contains phosphate group
The H2A and H2B
, a. Bind with linker DNA
b. Form tetramers
c. Form dimers
d. Are the same protein in two different forms - ANS✅✅c. Form dimers
The DNA fragment wrapping around the histone core of a nucleosome
a. Is about 50 bp
b. Is about 147 bp
c. Varies in length in different cells
d. Varies in length substantially among different species - ANS✅✅b. Is about 147 bp
Which of the following is false?
a. The number of H2A and H2B are always the same in regular nucleosome
b. The number of H3 and H4 are always the same in the regular nucleosome
c. The number of H3 is always more than H2A in regular nucleosome
d. The number of H3 is always the same as H2A in a regular nucleosome - ANS✅✅c. The number of
H3 is always more than H2A in regular nucleosome
If not associated with nucleosome, H2A and H2B are presented as __ in the cell.
a. Dimers
b. Monomers
c. Trimers
d. Tetramers - ANS✅✅a. Dimers
Which of the following is true?
a. Restriction cut the DNA from either 5' or 3' ends
b. Restriction that recognize 4 bp cut the DNA less frequently than those that recognize 6 bp
c. Restriction cut all the DNA with the right recognition sites
d. Restriction always generate sticky ends - ANS✅✅c. Restriction cut all the DNA with the right
recognition sites
Some of the DNA ends are called sticky ends because
