nucleotides

Question 1

2. Name the bond that joins nucleotides into a polynucleotide.

Answer 1

Phosphodiester.

Question 2

3. Explain how the organic bases help stabilise the structure of DNA

Answer 2

Hydrogen bonds between the complimentary pairs hold the two strands together; many hydrogen bonds provide strength;

Question 3

4. Explain how the structure of DNA is related to its function.

Answer 3

DNA is double stranded with a sugar-phosphate backbone to provide strength and stability; Its a large molecule to store lots of information; Its in a helix so it is compact; the base sequence allows proteins to be coded for; Its double stranded so it allows semi-conservative replication; There are weak hydrogen bonds to allow for breaking during replication;

Question 4

5. How do you find out the percentage/ frequency of bases in DNA?

Answer 4

All the bases will add up to 100%. Complimentary pairs will have the same frequency as each other in a double strand. They may have different frequencies in a single strand.

Question 5

6. Compare and contrast DNA and RNA.

Answer 5

DNA is a large molecule, whereas RNA is a smaller molecule; DNA contains Thymine, whereas RNA contains Uracil; DNA contains Deoxyribose sugar, whereas RNA contains Ribose sugar; Both composed of polymers of nucleotides; both contain phosphodiester bonds; both involved in protein synthesis; DNA stays in the nucleus, whereas RNA leaves the nucleus;

Question 6

7. Describe how the arrangement of prokaryotic DNA is different from eukaryotic DNA

Answer 6

Prokaryotic is circular, not linear; Prokaryotic is not associated with histones, eukaryotic is associated with histones; prokaryotes only have 1 piece of DNA plus plasmids, eukaryotes have many/multiple strands of DNA;

Question 7

8. Describe the structure of the DNA double helix

Answer 7

It is made of 2 strands of polynucleotides that run antiparallel; there are 4 different bases that pair through hydrogen bonding with their complimentary pair; cytosine to guanine, and adenine to thymine; The DNA is coiled in a helix;

Question 8

9. Why did many scientists doubt DNA carried the genetic code?

Answer 8

It is a relatively simple molecule with only four different bases.