3.1.5.1 Structure of DNA and RNA

Question 1

What is the role of DNA in living cells

Answer 1

Holds genetic information

Question 2

What is the role of RNA in living cells

Answer 2

Transfers genetic information from DNA to ribosomes

Question 3

What are ribosomes made of

Answer 3

RNA and proteins

Question 4

What are DNA and RNA polymers of

Answer 4

Nucleotides

Question 5

What are the three components of a DNA nucleotide

Answer 5

Deoxyribose a phosphate group and one of the organic bases adenine cytosine guanine or thymine

Question 6

What are the three components of an RNA nucleotide

Answer 6

Ribose a phosphate group and one of the organic bases adenine cytosine guanine or uracil

Question 7

What type of reaction forms a phosphodiester bond between nucleotides

Answer 7

Condensation reaction

Question 8

What is the structure of a DNA molecule

Answer 8

Double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs

Question 9

What is the structure of an RNA molecule

Answer 9

Relatively short polynucleotide chain

Question 10

Why did some scientists doubt that DNA carried the genetic code

Answer 10

Due to its relative simplicity

Question 11

Describe the structure of DNA.

Answer 11

1. Polymer of nucleotides;
   Accept ‘Polynucleotide’
   Accept for ‘phosphate’. phosphoric acid
2. Each nucleotide formed from deoxyribose, a phosphate (group) and
   an organic/nitrogenous base;
3. Phosphodiester bonds (between nucleotides);
4. Double helix/2 strands held by hydrogen bonds;
5. (Hydrogen bonds/pairing) between adenine, thymine and
   cytosine, guanine;

Question 12

Describe how a phosphodiester bond is formed between two nucleotides
within a DNA molecule.

Answer 12

1. Condensation (reaction)/loss of water;
2. (Between) phosphate and deoxyribose;
3. (Catalysed by) DNA polymerase;

Reject if DNA polymerase joins AT/GC OR
complementary nucleotides/bases OR forms
hydrogen bonds