Structure of DNA and RNA (3.1.5.1)

Question 1

Give examples of nucleic acids

Answer 1

• Deoxyribonucleic acid
• Ribonucleic acid

Question 2

What is a nucleotide made up of?

Answer 2

• Pentose sugar
• A nitrogenous base
• A phosphate group

Question 3

How does a DNA nucleotide and RNA nucleotide differ?

Answer 3

• DNA contains deoxyribose while RNA contains ribose
• DNA contains thymine while RNA contains uracil

Question 4

How are DNA polymers formed?

Answer 4

• Nucleotides within each strand join together through condensation reactions forming phosphodiester bonds between the deoxyribose sugar of one nucleotide and the phosphate group
• This creates polynucleotide chains with a sugar-phosphate backbone

Question 5

What is the structure of DNA?

Answer 5

• Polymer of nucleotides
• Each nucleotide formed from deoxyribose, a nitrogenous base and a phosphate group
• Nucleotides are joined by phosphodiester bonds to form a sugar-phosphate backbone
• DNA is double stranded and forms a double helix
• The two strands are held together by hydrogen bonds between complementary base pairs
• Adenine pairs with thymine and cytosine pairs with guanine

Question 6

How is the structure of DNA adapted for its function?

Answer 6

• The sugar-phosphate backbone → gives strength
• Being double stranded → so replication can occur using one strand as a template
• Being a large molecule → means that a large amount of information can be stored
• Many hydrogen bonds → gives stability to the molecule, individual hydrogen bonds being weak it allows the helix to unzip easily for replication
• Sequence of bases → codes for a specific sequence of amino acids in a polypeptide
• Complementary base pairing → enables information to be replicated accurately