In what direction does replication proceed?
Figure 3: Replication of the leading DNA strand is continuous, while replication along the lagging strand is discontinuous. After a short length of the DNA has been unwound, synthesis must proceed in the 5′ to 3′ direction; that is, in the direction opposite that of the unwinding.
What mode of replication is DNA replicated in?
DNA replicates by a semi-conservative method in which each of the two parental DNA strands act as a template for new DNA to be synthesized. After replication, each DNA has one parental or “old” strand, and one daughter or “new” strand.
In which direction and on which strands does DNA replication proceed from a replication origin on a chromosome quizlet?
– Each chromosome contains numerous origins. At each origin, the DNA unwinds producing a replication bubble. DNA synthesis takes place on both strands at each end of the bubble as replication forks proceed outward.
What occurs during replication quizlet?
What happens during replication? During replication, the DNA molecule separates into two strands and then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand. You just studied 19 terms!
What is the end result of replication?
The result of DNA replication is two DNA molecules consisting of one new and one old chain of nucleotides. This is why DNA replication is described as semi-conservative, half of the chain is part of the original DNA molecule, half is brand new.
How is replication accurate?
The cell has multiple mechanisms to ensure the accuracy of DNA replication. The first mechanism is the use of a faithful polymerase enzyme that can accurately copy long stretches of DNA. The second mechanism would be for the polymerase to catch its own mistakes and correct them. DNA is double-stranded.
Why is replication important?
Replication is an essential process because, whenever a cell divides, the two new daughter cells must contain the same genetic information, or DNA, as the parent cell. Once the DNA in a cell is replicated, the cell can divide into two cells, each of which has an identical copy of the original DNA.
What enzyme joins the Okazaki fragments together?
DNA ligase
What does 3 and 5 DNA mean?
The 5′ and 3′ mean “five prime” and “three prime”, which indicate the carbon numbers in the DNA’s sugar backbone. The 5′ carbon has a phosphate group attached to it and the 3′ carbon a hydroxyl (-OH) group. This asymmetry gives a DNA strand a “direction”.
Does DNA replication occur 5 prime to 3 prime?
DNA synthesis occurs only in the 5′ to 3′ direction. On the leading strand, DNA synthesis occurs continuously. On the lagging strand, DNA synthesis restarts many times as the helix unwinds, resulting in many short fragments called “Okazaki fragments.”
Why can new nucleotides only be added in a 5 to 3 direction?
DNA pol uses the energy provided by hydrolysis of the high-energy phosphate bond at the 5′ end of the incoming nucleotide to add it to the 3′ end of the growing DNA. Without the high-energy phosphate bond, the correct nucleotide can not be added. Without proofreading, life wouldn’t be good.
Why are new nucleotides added to 3 end?
It keeps every cell division on the same page, so to speak. Because DNA synthesis can only occur in the 5′ to 3′ direction, a second DNA polymerase molecule is used to bind to the other template strand as the double helix opens.
Why can DNA polymerase only add to the 3 end?
DNA Polymerase can only add nucleotides at the -OH group which is on the 3′ end. This free -OH group is necessary because it can carry out a nucleophilic attack on phosphate group of the incoming deoxyribonucleoside triphosphate which would contain the base that is complementary to the template strand.