The control of gene expression

Question 1

What is insertion?

Answer 1

when a nucleotide is randomly inserted into a DNA sequence
affects function of the polypeptide due to causing a frameshift
causes Huntington’s disease

Question 2

What is deletion?

Answer 2

when a nucleotide is randomly deleted in a DNA sequence
affects function of the polypeptide due to causing a frameshift
causes Cystic fibrosis

Question 3

What is substitution?

Answer 3

where a DNA nucleotide is swapped for a different one
It is:
silent - doesn’t alter amino acid sequence
missense - alters a single amino acid
nonsense - can create a premature stop codon
causes sickle-cell anaemia

Question 4

What is inversion?

Answer 4

when a single gene is cut in 2 places, inverted 180 degrees and re-joined
results in a non- functional protein
causes haemophilia A

Question 5

What is duplication?

Answer 5

where one or more nucleotides are duplicated in a DNA sequence
original gene is not gene
causes Charcot-Marie tooth disease

Question 6

What is translocation?

Answer 6

when a section of a chromosome is added to another chromosome that isn’t its homologous partner
Philadelphia chromosome that’s found in leukaemia cancer