Macromolecules: DNA & Evolution

Question 1

Importance of DNA

Answer 1

universal to most living things
… strong evidence for common ancestry of living things
biochemical evidence:
- universal genetic code (same bases, codons, protein synthesis process)
- DNA can be transferred from one organism to another (eg. vectors)
- same 20 amino acids used to build proteins

Question 2

Evolution of DNA

Answer 2

DNA has biodiversified over billions of years

• microorganism DNA simple circular, double-stranded chromosome
• evolved by mutations, larger, more complex (more genes, more introns, more complicated packaging with histones to prevent tangling)
• two species from common ancester, recent separation, DNA sequences more similar
• DNA mutations inevitable - as time passes, more mutations & greater difference from original DNA.

Question 3

Mutation

Answer 3

spontaneous or induced changes in genetic material

deletion, addition, inversion, substitution, duplication, translocation

Question 4

Genetic Diseases

Answer 4

Result of mutations

• sickle cell anaemia: faulty haemoglobin (one amino acid substitution) two genes, premature death; one gene, resistance to malaria
• cystic fibrosis (deletion of amino acid , c#7, in cell membrane protein, excess mucous production)

Question 5

Mutagenic Rate

Answer 5

chemicals (nucleotide sequence), radiation (chromosome breaks), viruses (addition of foreign DNA), high temperature