A principal difference between prokaryotic and eukaryotic
DNA replication is
a) completely different proteins/enzymes in eukaryotes
b) multiple origins in eukaryotes
c) no requirement for topoisomerase activity in prokaryotes
d) the absence of a nucleus in prokaryotes
Answers were Sorted based on User's Feedback
Answer / meenalkavi
the principal difference between prokaryotes and
eukaryotes is b)multiple origins in eukaryotes. although
prokaryotic replication takes place at a faster rate than
eukaryotic...the multiple origins in eukaryotes r
responsible for a speedy replication in eukaryotes than
prokaryotes..
Is This Answer Correct ? | 107 Yes | 19 No |
Answer / eb
Actually several of these answers are correct.
A. There are differnet enzymes involved in DNA replication
in prokaryotes and eukaryotes. For example in prokaryotes
there is an additional form of polymerase I discovered by a
scientist named Klenow. Thus it is named Klenow. This
prokaryotic polymerase I derivative functions like
polymerase I in every way except it does not have the 5'-
>3' exonuclease activity.
B. is obviously correct and has already been mentioned by
someone else.
C. Kinda goes along with answer a, but here it is anyway.
In Eukaryotes Topoisomerase acts to stabalize DNA during
replication by introducing negative coils. This activity
relieves the stress of unwinding the DNA and prevents
supercoiling. In eukaryotes this enzyme is called Gyrase.
Is This Answer Correct ? | 42 Yes | 15 No |
Answer / kuda
DNA gyrase belongs to a class of enzymes called
topoisomerase, otherwise you guys know what yo talking about
Is This Answer Correct ? | 16 Yes | 7 No |
Answer / pooja
a)In prokaryotes HU proteins creates negative coiling and
Tus protein terminates DNA replication. Topoisomerase IV
unlinks two circular DNA duplexes. In eukaryotes PCNA
protein prevents PCNA-Rfc-Polymerase delta complex from
dissociating from template. Telomerase are required for
synthesis in end region of lagging strand of DNA. This is
because replication takes place in opposite direction and
DNA polymerase is not capable of adding nucleotides in end
region.
b)Origin of replication always takes place from OriC. This
region is A-T rich. This is because there is double bond
between A and T it would require less energy for breakdown
compared to G-C. Probability of DNA replication to initiate
depends on presence of these nucleotides.
c)HU protein creates negative supercoils in prokaryotes.
Inorder to remove these supercoiling DNA gyrase(belongs to
class topoisomerase)is required.
d)In prokaryotes nucleus is not present, genetic material
is present within the nucleoid.
Is This Answer Correct ? | 10 Yes | 2 No |
Answer / ravi p
Replication in Prokaryotes
Initiation: DNA replication starts at oriC with three
repeats of a 13 bp sequence and four repeats of a 9 bp
sequence. A single complex of four to five DnaA protein
molecules binds to the four 9 bp repeats and successively
denatures DNA in region of three 13 bp repeats. DnaC
protein then loads DnaB protein onto unwound region. Two
ring shaped hexamers of DnaB, one loaded onto each DNA
strand, act as helicases, unwinding DNA bidirectionally and
creating two potential replication forks.
Dna Replication in Eukaryotes
Eukaryotic DNA replication proceeds in same way as that of
prokaryotic DNA replication except for following aspects:
1. Eukaryotic DNA has multiple “origin of replication”
sites, so several replication forks create many bubbles
along DNA length. These replication forks are formed at
autonomously replicating sequences (ARS) that contain
degenerate 11-bp sequences known as origin replication
element (ORE). ORE is located adjacent to an 80-bp AT rich
sequence that is easy to unwind.
2. DNA polymerases α and δ are main DNA replication enzymes
in eukaryotic cell. DNA polymerase α has 5’---> 3’
polymerase activity and synthesize primer on lagging strand
which are then extended by multisubunit DNA polymerase. DNA
polymerase δ has a 3’ à5’ proofreading exonuclease activity
and carry out both leading and lagging strand synthesis in
a complex comparable to dimeric bacterial DNA polymerase
III.
DNA polymerase ε removes primers of Okazaki fragments on
lagging strand. DNA polymerase γ is responsible for
replication of mt DNA.
3. Telomeres, structures at ends of linear eukaryotic
chromosomes, consist of many tandem copies of a short
oligonucleotide sequence with TxGy in one strand and CyAx
in complementary strand, where x and y are typically in
range of 1 to 4. Telomerase contains RNA that act as a
template for synthesis of TxGy strand of telomere.
Protein component of telomerase act as a cellular reverse
transcriptase for RNA-dependent DNA synthesis. After
extension of TxGy strand by telomerase, complementary CyAx
strand is synthesized by cellular DNA polymerases, starting
with an RNA primer.
.............. do reply and comments please
Is This Answer Correct ? | 9 Yes | 3 No |
Answer / eb
From the author of the second response given above:
In part C of my answer (above) I mistyped. Gyrase is the
enzyme is PROKARYOTES that relieves the stress of
supercoiling during DNA synthesis. In Eukaryotes this is
done by Topoisomerase.
Is This Answer Correct ? | 18 Yes | 14 No |
Answer / deepti dama
and also in eukaryotes there is the action on telomerase
which helps in eds sequence replication. this is absent in
prokaryotes.
Is This Answer Correct ? | 4 Yes | 1 No |
Answer / zainab
Actually,
1. Enzymes for DNA replication only found in eukaryotes are certain types of DNA ploymerases and telomerase.
Enzymes only found in prokaryotes are the different DNA ploymerases and DNA gyrate.
Enzymes common to both are helicase, primase, topoismerase and DNA ligase.
Answer: Yes
2. Yes in eukaryotesn(linear double stranded DNA) there are multiple origins of replication at which replication forks are formed in replicons. Prokaryotes only have a single origin of replication and thus a single replication fork formed.
Answer: yes
3. False. In bacteria, in addition to topoismerase, DNA gyrase also induces negative supercoiling.
4. No nucleus in prokaryotes and hence transcription is coupled to translation (while RNA transcript is being synthesised, a 70s ribosome will attach to the 5' end). True.
Hope is helped. How long ago was this posted?
Is This Answer Correct ? | 2 Yes | 0 No |
Answer / arif
1 number of origin site is one in case of prokaryote,and in
case of eukaryotes no of origin site is thousand
2 cell cycle is not differentiated in case of eukaryotes
cell is involed replication take place in s phase
Is This Answer Correct ? | 1 Yes | 1 No |
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