Question

1. practice: human inheritance and dna mutations

question 1
whats dna replication, and why is it an important part of cell division?
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question 2
name the five major enzymes involved in dna replication and briefly explain their roles in the process.
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question 3
discuss the differences between eukaryotic and prokaryotic cell division and dna replication.

Explanation:

Question 1: DNA replication is the process by which a double - stranded DNA molecule is copied to produce two identical DNA molecules. It is crucial for cell division because each new cell must receive an exact copy of the genetic material (DNA) to function properly and maintain the organism's genetic integrity.
Question 2:

1. Helicase: Unwinds the double - stranded DNA by breaking the hydrogen bonds between base pairs, creating a replication fork.
2. Primase: Synthesizes short RNA primers that provide a starting point for DNA polymerase to begin adding nucleotides.
3. DNA polymerase: Adds nucleotides to the growing DNA strand, following the base - pairing rules (A - T, C - G). In prokaryotes, DNA polymerase III is the main enzyme for elongation, while in eukaryotes, DNA polymerase α, δ, and ε are involved.
4. Ligase: Joins the Okazaki fragments (short DNA segments on the lagging strand) together by forming phosphodiester bonds.
5. Topoisomerase: Relieves the supercoiling tension ahead of the replication fork by cutting and rejoining the DNA strands.

Question 3: In eukaryotic cell division (mitosis and meiosis), DNA replication occurs during the S - phase of the cell cycle in the nucleus. The DNA is linear and associated with histone proteins to form chromatin. Multiple origins of replication are present. In prokaryotic cell division (binary fission), DNA replication is simpler, with a single origin of replication. The DNA is circular and not associated with histones. Prokaryotic DNA replication is faster and more straightforward compared to eukaryotic DNA replication.

Answer:

Question 1: DNA replication is the process of copying a double - stranded DNA molecule to produce two identical DNA molecules. It is important for cell division as each new cell needs an exact copy of the genetic material for proper function and genetic integrity.
Question 2: Helicase: Unwinds DNA. Primase: Synthesizes RNA primers. DNA polymerase: Adds nucleotides. Ligase: Joins Okazaki fragments. Topoisomerase: Relieves supercoiling.
Question 3: Eukaryotic cell division has DNA replication in nucleus during S - phase, linear DNA with histones and multiple origins. Prokaryotic cell division has simpler DNA replication with circular DNA, no histones and single origin.