MICR 271 - MODULE 4 Test Questions
Fully Solved.
What type of chromosomes do bacteria contain? - Answer Circular
What direction do circular chromosomes replicate in? - Answer Bi-directional!
What is the oriC? - Answer The origin, where DNA replication begins. This site is AT-rich and
thus is separated easier than G-C regions.
What happens once the DNA strands are separated? - Answer The replication forks will
proceed in opposite directions. This is driven by the replisome, before the two forks meet at the
termination site.
What is the replisome? - Answer Complex of multiple proteins involved in replication.
How are multiple copies of chromosomes created? - Answer When additional rounds of
replication begin at the oriC before the prior rounds reach the termination site.
What are catenated daughter chromosomes? - Answer Chromosomes that are interlocked.
This is the result of circular chromosomes replicating.
What is topoisomerase? - Answer A group of enzymes responsible for managing DNA tangling,
unwinding, and winding. They especially help in the decatenation of catenated daughter
chromosomes.
Name one advantage of having circular chromosomes. - Answer The chromosomes will not
have to worry about free end, or loss of DNA material after each replication round.
What is a helicase? - Answer Appears like a whirling molecular machine, that spins the DNA as
fast as a jet engine, and unwinds the double helix into 2 strands.
How are strands copied? - Answer One strand is copied continously, whereas the other strand
is copied backwards. The other strand will be drawn out repeatedly in loops and copied one
section at a time.
Explain the bacterial replication process: - Answer 1. The helicase will unwind DNA. The
lagging strand will be coated with single stranded DNA binding proteins (SSB) proteins. The
primase will produce a RNA primer.
, 2. DNA Pol III holoenzyme will be attached to DNA through a B-clamp. The t clamp loader will
load the DNA Pol III into the complex.
3. A core enzyme of Pol III will carry out the replication of the leading strand.
4. Two additional Pol III enzymes will carry out the replication of the lagging strand, and create
Okazaki fragments.
5. The core enzymes reach the completed region, and will be released as Okazaki fragments are
bound together. DNA Pol I will remove the RNA primer, fill gaps between DNA, and DNA ligase
will join all strands.
What do single stranded DNA binding proteins do? - Answer It has protective functions!
What is a holoenzyme? - Answer Apoenzyme + cofactor (coenzyme), in active form.
What is a core enzyme? - Answer Subunits of an enzyme that are required for catalytic activity.
Explain the eukaryotic replication process: - Answer 1. To activate the helicase and the
unwinding of the DNA, the helicase is complexed with additional proteins. Single stranded DNA
will be protected by the replication protein A.
2. Helicase will associate indirectly with primase (Pol ∞) to synthesize RNA primer.
3. Polymerase (Pol Ɛ) will be responsible for the creation of the leading strand. Pol 8 will be
responsible for the creation of the lagging strand. Proliferating cell nuclear antigen (PCNA) load
these polymerases into the DNA, and a replication factor C will carry this to DNA.
4. Okazaki fragments are shorter in eukaryotes. RNA primer will be removed by strand
displacement, filled in by Pol 8, and DNA ligase will repair gaps in strands.
Do replication forks work faster in humans or prokaryotes? - Answer Prokaryotes! This may be
because eukaryotes did not have selective pressures to adapt + create faster replication forks.
What 2 factors slowing down replication forks in prokaryotes? - Answer 1. Subject to cell cycle-
dependent regulation of replication initiation and termination + must deal with displacing
nucleosomes during replication.
Fully Solved.
What type of chromosomes do bacteria contain? - Answer Circular
What direction do circular chromosomes replicate in? - Answer Bi-directional!
What is the oriC? - Answer The origin, where DNA replication begins. This site is AT-rich and
thus is separated easier than G-C regions.
What happens once the DNA strands are separated? - Answer The replication forks will
proceed in opposite directions. This is driven by the replisome, before the two forks meet at the
termination site.
What is the replisome? - Answer Complex of multiple proteins involved in replication.
How are multiple copies of chromosomes created? - Answer When additional rounds of
replication begin at the oriC before the prior rounds reach the termination site.
What are catenated daughter chromosomes? - Answer Chromosomes that are interlocked.
This is the result of circular chromosomes replicating.
What is topoisomerase? - Answer A group of enzymes responsible for managing DNA tangling,
unwinding, and winding. They especially help in the decatenation of catenated daughter
chromosomes.
Name one advantage of having circular chromosomes. - Answer The chromosomes will not
have to worry about free end, or loss of DNA material after each replication round.
What is a helicase? - Answer Appears like a whirling molecular machine, that spins the DNA as
fast as a jet engine, and unwinds the double helix into 2 strands.
How are strands copied? - Answer One strand is copied continously, whereas the other strand
is copied backwards. The other strand will be drawn out repeatedly in loops and copied one
section at a time.
Explain the bacterial replication process: - Answer 1. The helicase will unwind DNA. The
lagging strand will be coated with single stranded DNA binding proteins (SSB) proteins. The
primase will produce a RNA primer.
, 2. DNA Pol III holoenzyme will be attached to DNA through a B-clamp. The t clamp loader will
load the DNA Pol III into the complex.
3. A core enzyme of Pol III will carry out the replication of the leading strand.
4. Two additional Pol III enzymes will carry out the replication of the lagging strand, and create
Okazaki fragments.
5. The core enzymes reach the completed region, and will be released as Okazaki fragments are
bound together. DNA Pol I will remove the RNA primer, fill gaps between DNA, and DNA ligase
will join all strands.
What do single stranded DNA binding proteins do? - Answer It has protective functions!
What is a holoenzyme? - Answer Apoenzyme + cofactor (coenzyme), in active form.
What is a core enzyme? - Answer Subunits of an enzyme that are required for catalytic activity.
Explain the eukaryotic replication process: - Answer 1. To activate the helicase and the
unwinding of the DNA, the helicase is complexed with additional proteins. Single stranded DNA
will be protected by the replication protein A.
2. Helicase will associate indirectly with primase (Pol ∞) to synthesize RNA primer.
3. Polymerase (Pol Ɛ) will be responsible for the creation of the leading strand. Pol 8 will be
responsible for the creation of the lagging strand. Proliferating cell nuclear antigen (PCNA) load
these polymerases into the DNA, and a replication factor C will carry this to DNA.
4. Okazaki fragments are shorter in eukaryotes. RNA primer will be removed by strand
displacement, filled in by Pol 8, and DNA ligase will repair gaps in strands.
Do replication forks work faster in humans or prokaryotes? - Answer Prokaryotes! This may be
because eukaryotes did not have selective pressures to adapt + create faster replication forks.
What 2 factors slowing down replication forks in prokaryotes? - Answer 1. Subject to cell cycle-
dependent regulation of replication initiation and termination + must deal with displacing
nucleosomes during replication.
