2.1.3 DNA replication

Question 1

by which process does DNA replicate

Answer 1

semi-conservative replication

Question 2

describe the first step of SC replication

Answer 2

the DNA double helix unzips
DNA helicase breaks H bonds between bases
creates 2 templates for new strands

Question 3

describe the second step of SC replication

Answer 3

free nucleotides in nucleus pair with the exposed bases
attracted to complementary pairs; reform H bonds

Question 4

describe the third step of SC replication

Answer 4

DNA polymerase catalyses formation of sugar-phosphate backbone
phosphodiester bonds form between the nucleotides
strands twist themselves back into a helix shape

Question 5

describe the fourth step of SC replication

Answer 5

fragments are sealed by DNA lignase which finalises DNA mols

Question 6

explain the role of DNA polymerase in DNA replication

Answer 6

it will proof reads the comp. bases as it moves along the strand
any errors detected are removes + replaced
ensures the template is accurately copied

Question 7

what happens when the DNA is not copied accurately

Answer 7

mistakes in the base pairings = mutations
change in AA sequence
can change the shape of proteins and their function (fold differently)

Question 8

describe the theory of conservative replication

Answer 8

a complete DNA mol acts as a whole template for a completely separate molecule