DNA Structure + Replication Flashcards
1
Q
4 features of the genetic code
A
Specific
Universal
Triplet
Degenerative
2
Q
Describe DNA structure
A
- nucleotide made from deoxyribose sugar, base + phosphate group
- Sugar phosphate backbone bonded by phosphodiester bonds
- right handed double helix held by H bonds
- strands run anti parallel
3
Q
Three features of DNA helix
A
Complementary
Antiparallel
Right handed
4
Q
Nucleoside vs nucleotide
A
Nucleoside has no phosphate
5
Q
Describe DNA packing
A
- DNA is wrapped around histones to form nucleosomes
- as DNA is wrapped more tightly solenoids are formed
- DNA coils up to form chromosomes
6
Q
Difference between ribose + deoxyribose
A
Oxygen has been removed in ribose
7
Q
Bond between nucleotides
A
Phosphodiester bonds
8
Q
When is DNA replicated during the cell cycle
A
S phase
9
Q
Outline initiation phase of DNA replication
A
- initiated by primase
- DNA strand is unwound by DNA helicase
- DNA polymerase binds to 3’ end
10
Q
Outline elongation phase of DNA replication
A
- DNA polymerase reads from 3’ to 5’
- DNA ligase binds Okazaki fragments on lagging strand
- newly formed DNA is wound into helix
11
Q
Outline termination of DNA replication
A
2 replication forks meet + DNA ligase joint them together
