D1.1 - DNA replication (3k)

Question 1

what is DNA replication?

Answer 1

DNA replication is a process that produces exact copies of DNA with identical base sequences

Question 2

what are the 3 main roles of DNA replication?

Answer 2

• reproduction - replication precedes binary fission and mitosis for asexual reproduction, and precedes meiosis for sexual reproduction
• growth - replication in multicellular organisms precedes production of more cells by mitosis
• tissue replacement - replication in multicellular organisms precedes mitosis, which produces new cells to replace worn out or damaged cells

Question 3

what is the process of DNA replication?

Answer 3

1. helicase unwinds the double helix structure and separates the two strands by breaking the hydrogen bonds between the bases
2. free DNA nucleotides are added using the existing strand as a template according to complementary base pairing, forming new hydrogen bonds
   - A and T
   - C and G
3. on each strand, DNA polymerase links nucleotides to form a new strand, by making covalent bonds
4. the products are two DNA molecules that are identical to each other and the original DNA molecule

Question 4

what is semi-conservative DNA replication?

Answer 4

the process by which two strands of DNA are separated and each is used as a template to guide the formation of a new strand using complementary base pairing

Question 5

what does the semi-conservative DNA replication result in?

Answer 5

this results in a pair of DNA molecules with identical base sequences, each consisting of one original strand and one new strand

Question 6

what is the role of complementary base pairing?

Answer 6

allows free-floating DNA nucleotides to base-pair with the unmatched nucleotides on the separated strands, forming hydrogen bonds

Question 7

what happens once DNA polymerase joins nucleotides?

Answer 7

once DNA polymerase joins the nucleotides into a new strand on each template strand, this forms two new double stranded DNA molecules that are exact copies of the original DNA molecule

Question 8

where does the high degree of accuracy in coping base sequences during DNA replication come from?

Answer 8

• the semi-conservative nature of DNA replication in which each separates strand is used as the template for the formation of a new strand
• complementary base pairing matching the correct nucleotide at each position along the template strand

Question 9

what is the role of helicase?

Answer 9

unwinds the DNA double helix and breaks the hydrogen bonds between bases, separating the DNA strands

Question 10

what is the role of DNA polymerase?

Answer 10

links nucleotides together to form a new strand of DNA by making covalent bonds between nucleotides and using the pre-existing strand of DNA as a template