1.5.1 Structure Of DNA

Question 1

Describe the basic functions of DNA and RNA in all living cells

Answer 1

DNA: holds genetic information which codes for polypeptides
RNA: transfers genetic information from DNA to ribosomes

Question 2

Name the two types of molecule from which a ribosome is made

Answer 2

• RNA and proteins

Question 3

Describe the differences between DNA and RNA nucleotides

Answer 3

DNA = deoxyribose sugar
RNA = ribose
DNA = thymine base
RNA = uracil base

Question 4

Describe how nucleotides join together to form polynucleotides

Answer 4

• condensation reaction, moving a water molecule
• between phosphate group of one nucleotide and sugar of another
• forming phosphodiester bonds

Question 5

Describe the structure of DNA

Answer 5

• polynucleotide
• each nucleotide formed from deoxyribose, a phosphate group and a nitrogen-containing organic base
• phosphodiester bonds join adjacent nucleotides
• 2 polynucleotide chain held together by hydrogen bonds
• between specific complementary base pairs A-T C-G
• double helix

Question 6

Describe the structure of RNA

Answer 6

• polymers of nucleotides
• each nucleotide formed from ribose sugar, a phosphate group and a nitrogen -containing organic base
• bases = uracil, adenine, cytosine, guanine
• phosphodiester bonds join adjacent nucleotides
• single helix

Question 7

Suggest how the structure of DNA relates to its functions

Answer 7

• two strands - both can act as templates for semi-conservative replication
• hydrogen bonds between bases are weak - strands can be separated for replication
• complementary base pairing - accurate replication
• many hydrogen bonds between bases - stable / strong molecule
• double helix with sugar phosphate backbone - protects bases / hydrogen bonds
• long molecule - store lots of genetic information (that codes for polypeptides)
• double helix (coiled) - compact