DNA Structure

Question 1

By which bonds nucleotides are joined

Answer 1

Phosphodiester bond (the phosphate group links the 3 carbon of a sugar to the 5 of the next sugar(

Question 2

What is polarity of a DNA

Answer 2

DNA has distinct 3 and 5 ends

Question 3

Sequence always specified as…

Answer 3

5 -> 3

Question 4

Features of dsDNA

Answer 4

1) two strands are antiparallel (opposite in direction)
2) 2 strands are complimentary (A always pairs with T by 2 hydrogen bonds; G always pairs with C by 3 hydrogen bonds)
3) the amount of A equals the amount of T; the amount of C equals the amount of G (Chergaffs rule)

Question 5

Chargaffs rules

Answer 5

%A = %T (%U)
%G = %C
% purines = % pyrimidines

Question 6

What is B-DNA?

Answer 6

Right-handed double-helical molecule (Watson-Crick DNA)

Question 7

On the outside of the helix —

Answer 7

The hydrophilic sugar-phosphate backbone

Question 8

In the centre of the molecule —

Answer 8

Hydrogen-bonded base pairs

Question 9

How many base pairs are in one turn of the helix

Answer 9

10

Question 10

Another form of dna?

Answer 10

Left-handed double-helical Z-DNA

Question 11

What happens during the DNA denaturation?

Answer 11

Disrupting of hydrogen bonds
Separating of two strands
Covalent bonds are not broken!

Question 12

When denaturation and renaturation can be used?

Answer 12

Souther blot, PCR