DNA Replication Process

DNA Replication Process

Initiation:

is the point where the splitting starts and is called the “origin of replication,” creating the replication fork.

On Leading Strand 5”-3” (replication is continuous)

  1. DNA helix is unwounded by helicase by breaking the hydrogen bonds between the two strands (The splitting happens in places of the chains which are rich in A-T).
  2.  Binding of RNA primase adds RNA primer for DNA polymerase to start replication.
  3. Single-binding proteins keep strands separated.
  4.  Topoisomerase relieves strain caused by the DNA unwinding

Elongation:

adding of nucleotides

On lagging strands 3”-5” (replication occurs from multiple primers)
*cannot be read by DNA poly.

  1.  in this process, nucleotides are added to the 3” end of the Okazaki fragments (small fragments).
  2. Primers continuously laid down
  3. DNA ligase connects the fragments together

Replication Fork
Termination:

This is when the DNA polymerase stops when it reaches a section it has already replicated. At the end of the chromosome (telomere), replication is impossible because they have non-coding genes.
Things to know:

  • In eukaryotic cells-multiple origins of replication
  •  In prokaryotes-one origin of replication
  •  Telomeres are not passed on by parents because they are too short.

Why does DNA replication occur? So that the new nucleus can pass on our DNA to the daughter cells.

Multiple Choice Questions

1. DNA synthesis continues

a. in the 3’ to 5’ direction
b. in the 5’ to 3’ direction.
c. Both directions.

2. Which one of the following is incorrect about DNA replication?

a. The end of a DNA strand that has a phosphate group attached to the number 5 carbon is the 5 prime end of the other.
b. DNA is according to semi-conservative replication produces one original strand and one new strand. In this type, both parental charters are in the offspring DNA.
c. In another step DNA polymerase, III doesn’t have to synthesize the new DNA on the leading strand in the process.

3. If topoisomerase was not present what will happen:

a. It would disrupt the strand and prevent binding and the other enzymes from doing their job and stop the replication process.
b. Mutations would occur
c. Helicase would not unwind the double helix

4. What is the complementary sequence for GCTAAAGTC

a.AAGCCCAGA
b. CGATTTCAG
c. AAGCCCTGA
d. GGATTTCAG

5. Replication origins are essentially easy to open. Why is this?

a. The origins have a mass amount of A and T nucleotides.
b. The origins have a mass amount of G and C nucleotides.
c. The origins have a mass amount of A and U nucleotides.
d. The origins have the same amount of A, T, G, and C nucleotides.

The process of DNA replication is one of the most important processes in the human embryonic and post-embryonic stage without any application there is no chances for human being for survival because when DNA is replicated then only it is possible that the DNA will transfer from parents to offspring. The process of DNA replication takes place within the cell nucleus and there are three types of DNA replication namely the conservative model of DNA replication non-conservative mode of DNA replication dispersive model of DNA replication. According to the discoverer, the process of DNA replication is mainly according to the semiconservative model of DNA replication.

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