Structure of Nucleic Acids Flashcards
Does all RNA code for a protein?
No
Briefly describe the structure of purines
Nitrogen rich heterocyclic double ring structure
Briefly describe the structure of pyrimidine
N rich heterocyclic single ring structure
Which carbon atoms do phosphodiester linkages form between?
5’ and 3’
Why is RNA unstable?
The hydroxyl on the 2’ carbon acts as a nucleophile to break the phosphodiester linkage between nucleotides
What is annealing?
Aka renaturation. Conversion single strands into double helical DNA
Are phosphate backbones closer together on the major or minor groove?
Minor
What is persistence length?
The length of DNA alongwhich a thermally excited bend of 1 radian typically occurs
At a length of more than 150 base pairs is DNA flexible or stiff?
Flexible
At a length of less than 150 base pairs is DNA stiff or flexible?
Stiff
Why is short DNA stiff?
- Electrostatic repulsion of phosphates
- Compressive base stacking
Why does electrostatic repulsion of phosphates not cause stiffness in long DNA?
In long molecules the repulsion is distributed across the whole molecule
Give an example of a protein which can bind to specific DNA sequences
TATA binding protein
Give 3 ways proteins can interact with DNA
- Recognise and bind to specific DNA sequences
- Recognise structural features e.g. DNA damage
- Bind DNA non-specifically
Give an example of a protein which binds non-specifically to DNA
Histone proteins
