DNA

Question 1

What are the two types of nucleic acid?

Answer 1

Deoxyribose nucleic acid (DNA)
Ribonucleic acid (RNA)

Question 2

What is the structure of nucleotides?

Answer 2

Condensation reactions like the Penrose sugar, phosphate group and organic nitrogenous base components together via covalent bonds.
The phosphate links neighbourhood sugars together to form a sugar phosphate backbone.
Many nucleotides join to form nucleic acid

Question 3

What are the 2 classifications of bases?

Answer 3

Pyrimadines, 1 ring: cytosine, thymine and uracil
Purine, 2 rings: adenine, guanine

Question 4

How many bonds to each complementary base pairings have?

Answer 4

GC = 3 bonds
A-T/U=2 bonds

Question 5

What is the function of DNA?

Answer 5

The sequence of bases in DNA codes for the sequence of amino acids in the polypeptide chain that determines the shape and function of the protein.
Therefore they determine all ciharacterteristics of an organism.
Enzymes are proteins
Involved in cell division, replicated to make new cell.
RNA used in protein synthesis

Question 6

What are differences between DNA and RNA polymer

Answer 6

DNA: very large, double helix, in nucleus
RNA: much shorter, single strand or double helix, in nucleus + cytoplasm

Question 7

What is process of DNA replication (1/2)

Answer 7

1. 2 strands of DNA split apart by action of DNA helicase which breaks hydrogen bonds holding bases together
2. Each strand acts as a template
3. Free DNA nucleotides present in nucleus. 2 extra phosphates have been fed to them, which activates them.
4. Bases of the activated free nucleotides pair up with complementary base on each of old DNA strands.

Question 8

Process or DNA replication (2/2)

Answer 8

4. DNA polymerase links sugar and phosphate groups of nucleotides together through condensation reactions
5. 2 extra phosphate groups break away
6. 2 identical daughter DNA strands are result (energy from ATP required for DNA polymerase)
7. This is semi-conservative replication because each new daughter DNA molecules conserves one ironical strand has one new strand.
8. Enzymes proof read DNA to correct mistakes.

Question 9

What is theories of DNA replication

Answer 9

Seni conservative: One strand original, other synthesised
Dispersive : bits of original + synthesised in both strands
Fully conservative

Question 10

How does Measlesohn + Staal prove semiconservative theory?

Answer 10

1. E Coli grown in Medium containing 15N which is heavy
   Bacterial DNA composed of 15N which when extracted and centrifuged makes one low band of DNA.
   Then DNA placed in medium containing 14N. Left for 50 mins, extraction and centrifuged making one higher band.
   Then after another division, one 15N/14N band and one even higher 14N
   3rd division: 2 bands but higher 14N grows, 14/15N shrinks