UNIT 1 (topic 5) nucleic acid Flashcards
1
Q
describe the structure of a nucleotide
A
phosphate group, deoxyribose sugar (bonded with phosphodiester bond) and a nitrogenous base (bonds to other base with H bonds)
2
Q
why is double stranded DNA known as anti-parallel
A
strands run in opposite directions (3’ to 5’ and 5’ to 3’)
3
Q
the four bases of a DNA molecule
A
adenine to thymine
guanine to cytosine
4
Q
describe the relationships and pairs of the DNA bases
A
adenine and guanine - purines
cytosine and thymine - pyrimidines
A-T = forms 2 hydrogen bonds
C-G = forms 3 hydrogen bonds
5
Q
explain semi-conservative replication
A
- one strand breaks and forms replicas by usig half old and half new
- DNA helicase unwinds the strands by breaking the H bonds
- free nucleotides are attracted to the complementory bases (A-T and C-G)
- DNA plymerase creates a phosphate bavkbone by making phosphodiester bonds
