Interested to Buy Any Domain ? << Click Here >> for more details...
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
- 9 Answers
- 36732 Views
- I also Faced
- E-Mail Answers
Answer Posted / 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 |
Post New Answer View All Answers
What is the property of Alkaline earth metal Ions?
Into which two groups can the nitrogen-containing bases that form dna and rna be classified? What is the criterion used in that classification?
Hi, I am venkat. I am done with M.Sc Medical Biochemistry in the year 2007. I got rejected 3 times at US consulate, and the reason they say is why are you going agian for PG when you have already done PG, and they are not ready to get convinced only on this issue.
Name the first synthetic organic compound. Who proposed it and from which compound?
What is the other name of sulphur?
What are some factors that can lead to protein denaturizing?
Do enzymes act better under acid or basic ph?
Give the formula for Peral Ash?
Bacteria are prokaryotic cells, i.e., They do not have membrane-delimited nucleus. Eukaryotes have cells with delimited nucleus. Where in these types of cells can dna are found?
Which form of isomers of a substance is more stable?
Why are right-handed helices more stable than left-handed helices?
What are hydrophobicity scales, and how are they used?
Does ph affect the enzyme activity?
What is isomerism?
Which compound is involved in reducing levels of homocysteine in the blood?
