DNA structural and functional Flashcards
A phosphodiester bond joins
two nuleotides forming a dinucleotide
sequences are always written in which direction?
5’ -3’
The major groove always has - proteins
4 - H bond acceptor, H bond donor, H atoms, Methyl group
the minor groove always has - proteins
3
the twist angle/rotation per residue is
28 - 42
how many base pairs are there during one 360 turn
10.5
Properties of B DNA (diameter, A/bp, bp/turn)
- 5 A
- 4 A/bp
- 4 bp/turn
Properties of A DNA (diameter, A/bp, bp/turn)
25.5 A
2.3 A/bp
11 bp/turn
bases are tilted to 19’
anthrax is due to which bacteria
bacillus antracis
what produces neurotoxin botulinum
clostridium botulinum: the botulinum toxin causes severe flaccid paralytic disease. Are destroyed at 100’. Produces heat resistant spores
Botulinum toxin is also used for?
paralytic effects of human voluntary musculature.
Z and B DNA are both which sided?
left handed
what is the repetitive unit in Z-DNA
a dinucleotide
is Z DNA more stable than B DNA
no, due to the electrostatic repulsion between the negatively charged phosphates on opposite strands which are nearer in this conformation
what is the function of Z-DNA
it can relax DNA supercoils that are produced when the 2 strands are separated thus facilitating gene expression
what are the stabilizing forces
hydrophobic interactions
stacking interactions
hydrogen bonding
what are the destabilizing interactions
electrostatic repulsions
dipole
molecules or atoms with equal and opposite electrical charges separated by a small distance
order of strength of bonds
VDW
the donor atom in an H bond is
the F, N, O
specificities of H bonds
they are directional and are specific , they are strongest when 3 atoms are in a line
denaturation can occur by
heat, strong bases/acids, organic solvents, inorganic salt
spectrophotometer
device that measures the absorbance of a solution as light of a specified wavelength is passed through it
the hyperchromic shift occurs during
heating
the hypochromic shift occurs during
cooling
