Question

Write the correct steps of dna replication in the order that they occur.

Answer 1

Answer:. Initiation- elongation- termination

Explanation: The first step, initiation, is when the DNA unzips and unfolds thereby leading to a breakage of the bond (hydrogen bond) with holds the bases of the DNA together, giving free strands of DNA.

Secondly, the elongation step. A piece of RNA binds to the DNA strand and also an enzyme known as DNA polymeraseIII binds to the piece of RNA (primer). This binding leads to the addition of newer base pairs to the strands thereby elongating it.

Then the termination step, once the strands are formed, those RNA primers are removed from the strand by the action of an enzyme called exonuclase and are being replaces by the appropriate bases.

Answer 2

Answer:

1)Initiation of replication

2)Directional growth of a new strand

3)Proof reading of the DNA polymerase

4)DNA damage and repair

Explanation:

The steps of DNA replication are as follows:

1)*INITIATION OF REPLICATION : This starting point of replication is a short segment of RNA. The RNA is placed just by one of the open strand, that is, the one that would replicate first out of the two. The RNA molecule hard in this process is called RNA primer synthesized by the RNA polymerase. It must be complementary to the DNA strand to be replicated. With the RNA primer in place, the DNA polymerase proceeds to put together nucleotides one by one, which are complementary to the single parent strand.

2) *DIRECTIONAL GROWTH OF A NEW STRAND:Here, the reaction involving 5'-phosphate on an incoming nucleotide and the free 3'-OH on the growing nucleotide is catalysed by the DNA polymerase. This ensures that the new stands grows in a 5'-3' direction. The double helix runs antiparallel (i.e, parallel and in opposite directions. In this stage, the Okazaki fragment occurs, so also the leading and lagging strand.

3)*PROOF READING ACTIVITY OF DNA POLYMERASE: during the replication process, a mismatch of bases may occur. This situation where a C(cytidine monophosphate) may be brought in to pair with an A(adenosine monophosphate). The C may be added to a 5' to 3' nucleotide elongation but the hydrogen bond may not form since it is not complementary to A. The mismatched C would be hydrolysed by the 3'-5'exonuclease of DNA polymerase. Experiments have shown that base pairs are usually crosschecked at least twice to ensure that DNA replication is very accurate.

4)*DNA DAMAGE AND REPAIR : Even though DNA is relatively stable compared to other biological molecules, it is however still susceptible to alternations. Some of these alternations may be spontaneous or induced by external agents. Spontaneous alternations may occur in the form of loss of bases or loss of amino groups(deamination).