A1.2 Nucleic Acids

Question 1

What is DNA?

Answer 1

The genetic material of all living organisms.

Question 2

Components of a nucleotide

Answer 2

• Pentose sugar (deoxyribose for DNA & ribose for RNA)
• Acidic phosphate group
• A nitrogenous base (CGAT for DNA)

Question 3

Role of sugar-phosphate bonding and the sugar-phosphate “backbone”.

Answer 3

The phosphate group of one nucleotide forms a covalent bond to the pentose sugar of the next one. –> forms large polymer –> nucleic acids

Question 4

What are the names of the nitrogenous bases?

Answer 4

Adenine, Thymine, Guanine, Cytosine, Uracil

Question 5

Drawing reminders

Answer 5

In diagrams of DNA structure:
- draw antiparallel strands
- show A paired with T , and G paired with C

Draw and recognize the diagrams of single nucleotides and RNA polymers.

Question 6

Differences between DNA and RNA

Answer 6

1. DNA is double-stranded, RNA is single stranded.
2. DNA contains deoxyribose, RNA contains ribose.
3. DNA nitrogenous bases are Adenine, Thymine, Guanine, and Cytosine. For RNA, Thymine is replaced with Uracil.

Question 7

Role of complementary base pairing

Answer 7

• Complementary base pairing happens when hydrogen bonds form between a pair of bases (A with T & G with C).
• Only these pairs can form hydrogen bonds.
• Allows genetic info to be replicated and expressed.

Question 8

The diversity of possible DNA sequences

Answer 8

The four bases can be arranged in any order –> Limitless capacity for storing information, with diversity by any length of DNA molecule and any base sequence possible.