3.8.1 - Alterating the Sequence of Bases in DNA Can Alter Protein Structure

Question 1

gene mutations

Answer 1

• might arise during DNA replication
• occur spontaneously
• rate increased by mutagenic agents
• can result in diff. amino acid sequence in encoded polypeptide

Question 2

addition mutation

Answer 2

• extra base added into sequence
• all bases that follow moved along (frame shift to the right)
• causes most amino acids coded for by codons at/after the addition to change

Question 3

deletion mutation

Answer 3

• loss of a base
• causes frame shift to the left
• all bases move along to replace the one that was lost
• also changes most of the codons at/after the deletion

Question 4

substitution mutation

Answer 4

• replacement of a base by a different base
• point mutation
• where the wrong base is inserted and replaces the original base

Question 5

inversion mutation

Answer 5

• group of bases separated from DNA rejoins at same position but in inverse order
• base sequence is reversed

Question 6

duplication mutation

Answer 6

• one or more bases are repeated
• frame shift to the right

Question 7

translocation mutation

Answer 7

• group of bases separated from DNA sequence on one chromosome and inserted into DNA sequence of another chromosome
• produces an abnormal phenotype