INTRODUCTION TO MOLECCULAR CELL BIOLOGY TEST
BANK CHAPTER6 EDITION QUESTIONS AND ANSWERS
WITH RATIONALISED ANSWERS GRADED A+
The process of DNA replication requires that each of the parental DNA strands be
used as a ____________ to produce a duplicate of the opposing strand.
(a) catalyst
(b) competitor
(c) template
(d) copy - ANSWER-(c) template
DNA replication is considered semiconservative because
__________________________________.
(a) after many rounds of DNA replication, the original DNA double helix is still intact.
(b) each daughter DNA molecule consists of two new strands copied form the parent
(c) each daughter DNA molecule consists of one strand from the parent DNA
molecule and one new strand. - ANSWER-(c) each daughter DNA molecule consists
of one strand from the parent DNA molecule and one new strand
The classic experiment conducted by Meselson and Stahl demonstrated that DNA
replication is accomplished by employing a ______________ mechanism. -
ANSWER-semiconservative
Initiator proteins bind to replication origins and disrupt hydrogen bonds between the
two DNA strands being copied. Which of the factors below does not contribute to the
relative ease of strand separation by initiator proteins?
(a) replication origins are rich in A-T base pairs
(b) the reaction can occur at room temperature
(c) they only separate a few base pairs at a time
(d) once opened, other portions of the DNA replication machinery bind to the origin -
ANSWER-(b) the reaction can occur at room temperature
If the genome of the bacterium E. coli requires about 20 minutes to replicate itself,
how can the genome of a fruit fly be replicated in only 3 minutes?
(a) The fruit fly genome is smaller than E coli
(b) Eukaryotic DNA polymerase synthesizes DNA at a much faster rate than
prokaryotic
(c) The nuclear membrane keeps the fruit fly DNA concentrated in one place in the
cell, which increases the rate of polymerization
(d) Fruit fly DNA contains more origins of replication than E coli DNA. - ANSWER-(d)
Fruit fly DNA contains more origins of replication than E coli DNA
True or false?
, When DNA is being replicated inside a cell, local heating occurs, allowing the two
strands to separate. - ANSWER-False. This is accomplished by initiated proteins
binding at the origin of replication.
True or false?
DNA replication origins are typically rich in G-C base pairs. - ANSWER-They are rich
in A-T base pairs which makes it easier for them to separate the strands because
they are only held together by two hydrogen bonds
True or false?
Meselson and Stahl ruled out the dispersive model for DNA replication. - ANSWER-
true
True or false?
DNA replication is a bidirectional process that is initiated at multiple locations among
chromosomes in eukaryotic cells. - ANSWER-True
How many replication forks are formed when an origin of replication is opened? -
ANSWER-2
How does the total number of replication origins in bacterial cells compare with the
number of origins in human cells? - ANSWER-1 versus 10,000
Which of the following statement correctly explains what it means for DNA replication
to be bidirectional?
(a) The replication forks formed at the origin moved in opposite directions.
(b) the DNA replication machinery can move in either direction on the template
strand
(c) The replication fork can either open or close depending on the condition
(d) Replication form movement can switch directions when the fork converges on
another replication fork. - ANSWER-(a) The replication forks formed at the origin
move in opposite directions.
The chromatin structure in eukaryotic cells is much more complicated than that
observed in prokaryotic cells. This is thought to be the reason that DNA replication
occurs much faster in prokaryotes. How much faster is it?
(a) 2x
(b) 5x
(c) 10x - ANSWER-(c) 10x
DNA polymerase catalyzes the joining of a nucleotide to a growing DNA strands.
What prevents this enzyme from catalyzing the reverse reaction?
(a) hydrolysis of pyrophosphate (PPi) to inorganic phosphate (Pi)+Pi
(b) release of PPi from the nucleotide
(c) hybridization of the new strand to the template
(d) loss of ATP - ANSWER-(a) hydrolysis of pyrophosphate (PPi) to inorganic
phosphate (Pi)+Pi
Which of the following statements is true with respect to this in virto replication
system?
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