SHORT ESSAY QUESTIONS Explain how and where DNA Replication occurs and how this
ID: 219333 • Letter: S
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SHORT ESSAY QUESTIONS Explain how and where DNA Replication occurs and how this fits into the cell cycle and the process of mitosis. Include the following processes in your explanation: 1) The purpose/function of the nucleus 2) How DNA Replication occurs Be sure to discuss ALL the enzymes/proteins that are involved DNA Replication occurs 4) The many steps of the cell cycle and how DNA replication is involved Mention when DNA replication occurs 5) How DNA Replication is involved in Mitosis Discuss why replication is important before MitosisExplanation / Answer
1. The function of the nucleus:
2. DNA Replication:
DNA replication occurs in three stages- initiation, elongation and termination.
Initiation:
Elongation:
Termination:
Termination of replication occurs when the two replication forks meet each other on the opposite end of the parental chromosome.
3. Replication occurs in the nucleus of the cell.
4. The cell cycle is divided into: interphase, M phase (mitotic phase) and cytokinesis. During interphase, the cell grows and duplicates its DNA. Interphase can be divided into G1, S, G2 phase. DNA replication occurs in S phase.
- The nucleus is an organelle which is found in eukaryotic cells. Inside its nuclear membrane, the nucleus contains the majority of the cell's genetic material.
- Nucleus maintains the security of the genes and also controls the functions of the cell by regulating gene expression.
- Production of ribosomes in the nucleolus.
- Selective transportation of regulatory factors through nuclear pores.
- Storage of proteins and RNA.
2. DNA Replication:
DNA replication occurs in three stages- initiation, elongation and termination.
Initiation:
- DnaA targets AT-rich origin site.
- Proteins recruited to form the pre-replication complex.
Elongation:
- Replication bubble is formed.
- SSB proteins coat the single strands.
- Primase makes an RNA primer, or a short stretch of nucleic acid complementary to the template, that provides a 3' end for DNA polymerase to work on.
- DNA pol III is recruited, which synthesizes DNA at 5' to 3' direction.
- Leading strand and lagging strand is produced.
- Lagging strand produces small fragments known as Okazaki fragments
- Topoisomerases inhibit the formation of super loop.
- DNA pol I remove the RNA primer.
- Nicks is sealed by ligase.
Termination:
Termination of replication occurs when the two replication forks meet each other on the opposite end of the parental chromosome.
3. Replication occurs in the nucleus of the cell.
4. The cell cycle is divided into: interphase, M phase (mitotic phase) and cytokinesis. During interphase, the cell grows and duplicates its DNA. Interphase can be divided into G1, S, G2 phase. DNA replication occurs in S phase.
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