Question

Create a table including the names and functions of the major enzymes and proteins involved in DNA replication.

1.Enzyme

2.Helicase

3.Primase

4. Topoisomerase

5. DNA polymerase 1

6. DNA polymerase 2

7. DNA polymerase 3

8. Ligase

Answer 1

DNA replication is the process by which DNA makes a copy of itself during cell division.

DNA replication is semiconservative. Each strand in the double helix acts as a template for synthesis of a new, complementary strand.

Enzymes and proteins involved in DNA replication are-

1) Single-stranded DNA-binding protein (SSB)- binds to single-stranded regions of DNA. During DNA replication, SSB molecules bind to the newly separated individual DNA strands, keeping the strands separated by holding them in place so that each strand can serve as a template for new DNA synthesis.

2) Primase- Primase is an enzyme that synthesizes short RNA sequences called primers. Primase functions by synthesizing short RNA sequences that are complementary to a single-stranded piece of DNA, which serves as its template.

3) DNA helicases- These are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.

4)Topoisomerase- Topoisomerase plays an important maintenance role during DNA replication. This enzyme prevents the DNA double helix ahead of the replication fork from getting too tightly wound as the DNA is opened up.

5)DNA polymerase I- DNA polymerase I is an enzyme that participates in the process of prokaryotic DNA replication.The physiological function of Pol I is mainly to repair any damage with DNA, but it also serves to connect Okazaki fragments by deleting RNA primers and replacing the strand with DNA.

6) DNA polymerase 2- This enzyme has an associated 3′→5′ exonuclease activity along with primase activity. DNA Pol II is a high fidelity enzyme. DNA Pol II can proofread and process mismatches caused by the Pol III.

7) DNA polymerase III- DNA polymerase III holoenzyme is the enzyme primarily responsible for replicative DNA synthesis in E. coli. It carries out primer-initiated 5' to 3' polymerization of DNA on a single-stranded DNA template, as well as 3' to 5' exonucleolytic editing of mispaired nucleotides.

8) DNA ligase- DNA ligase facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. it ligates the nascent DNA of the lagging strand after the Ribonuclease H has removed the RNA primer from the Okazaki fragments.