DNA Flashcards
1
Q
Structure of DNA
A
- deoxyribose sugar ( one less oxygen than RNA)
- phosphate group
- nitrogen containing bases A,T,G,C
2
Q
How is dinucleotide formed ?
A
- 2 mononuceotides joined through condensation reac.
3
Q
How does phosphodiester bond formed ?
A
- between deoxyribose sugar of 1st mononucleotide and phosphate of 2nd
4
Q
Base pairing in DNA
A
Adenine - thymine
Guanine - cytosine
All bases are in equal proportion
5
Q
What bond forms between bases in pairs ?
A
Hydrogen bonds
A-T 2 hydrogen bonds
G-C 3 hydrogen bonds
6
Q
The double helix
A
- as anti parallel
- uprights composed of deoxyribose sugar and phosphate ( backbone of DNA)
- base pairs in the middle
7
Q
Adaptations of DNA (5)
A
- a very stable structure
- hydrogen bonds between 2 nucleotides
- large molecule
- position of base pairs
- base pairs
8
Q
Functions of adaptations (5)
A
- stable SO can passes info from generation to next without changes, rarely mutate
- H bonds SO allow nucleotides to be separated during DNA replication and protein synthesis
- Large molecule SO can carry large amount of genetic information
- B.P positioned inside backbones SO can be protected from the effect of outside chemical / physical forces
- B.P SO DNA able to replicate and transfer information as mRNA
9
Q
Why is DNA a stable molecule ?
A
- H bonds link B.P = the more G-C ratio= more stable the DNA
- base stacking interactive forces = hold them as a molecule
10
Q
Purpose DNA replication
A
- ensure all daughter cells have the same genetic informations to produce enzymes and other proteins that they need
11
Q
Semi- conservative replication
A
- because one of the parental strand is conserved into a template plus a newly synthesised strand to form a complete DNA molecule
12
Q
1st stage of DNA replication
A
- DNA helicase breaks H bonds between bases in pairs between 2 strand of double helix = causes DNA to unwind
13
Q
2nd stage of DNA replication
A
- parental DNA as a template and free floating nucleotides attracted to complementary base pairs on the template strands of parental dna
14
Q
3rd stage of dna replication
A
- adjacent nucleotides joined, DNA polymerase catalyse to form phosphodiester bond
15
Q
4th stage
A
- 2 sets of daughter DNA forms = contains one parental and one new synthesised DNA
