DNA structure (lecture 10)

Question 1

outline chargaffs 2 findings about DNA variation

Answer 1

consistent similarities between the number of A & Ts and the number of G & Cs in different species, therefore rule #1: [A]=[T] and [C]=[G]
rule #2: the composition of DNA varies between species

Question 2

outline a singular DNA molecule structure

Answer 2

a double stranded helix molecule (structurally antiparallel) with nucleotide bases pairings

Question 3

outline the nucleotide bases and their configurations

Answer 3

pyrimidines = C (cytosine) & T (thymine)
purines = G (guanine) & A (adenine)

Question 4

how are nucleotide bases paired together

Answer 4

each pair is bonded facing the middle together by hydrogen bonds:
A & T = 2 hydrogen bonds
G & C = 3 hydrogen bonds
each DNA (and RNA) strands are synthesised 5’ to 3’ direction, 5 pairing with the 3 end within the double helix.

Question 5

outline how semi-conservitave DNA replication occurs

Answer 5

the parent strands split apart and identically replicate their pairing in new strands allowing for cell replication in growth, repair & pregnancy

Question 6

outline the formation of a polynucleotide

Question 7

outline the formation of a phosphodiester bond