Types of mutations

Question 1

Point Mutation

Answer 1

Occurs solely in the genome
A single base pair is deleted from, substituted or added to the sequence

Question 2

Substitution (PM)

Answer 2

When a single nitrogenous base is substituted for another

Question 3

Insertion (PM)

Answer 3

When a single nitrogenous base is inserted or added to the sequence

Question 4

Deletion (PM)

Answer 4

When a single nitrogenous base is deleted entirely from the sequence

Question 5

Silent mutations

Answer 5

Cause no change to the amino acid sequence
Only occur when more than one codon codes for a particular amino acid
Possible due to degenerate nature of DNA

Question 6

Missense mutations

Answer 6

Result in an amino acid being replaced
Effect of this replace varies depending on position in protein
Whether the altered property can function

Question 7

Nonsense mutation

Answer 7

Involve the insertion of the stop codon (TAA, TAG OR TGA)
Results in the transcription stage stopping prematurely
The protein is not completely formed

Question 8

Chromosomal mutation

Answer 8

Move genes to other parts of a chromosome
Crossing over occurs in meiosis
Parts of one chromatid break off and become attached to another
Result in the rearranging of some genes

Question 9

Duplication (CM)

Answer 9

Occurs when there are two copies of the same section on a chromosome

Question 10

Insertion (CM)

Answer 10

Occurs when a segment of one chromosome breaks away
Break away is inserted into another

Question 11

Deletion (CM)

Answer 11

Occurs when part of a chromosome breaks off and is lost

Question 12

Inversion (CM)

Answer 12

Occurs when part of a chromosome breaks off and re-attaches in the opposite direction
This reverses the order of genes

Question 13

Translocation (CM)

Answer 13

Occurs when a piece is moved from one chromosome to a non-homologous chromosome

Question 14

Frameshift (PM)

Answer 14

Occurs when extra bases are added or deleted from DNA strand
Transcription of DNA is read in groups of three bases
Deletion or insertion of three, or a multiple of three, only affects one amino acid
More or less than three, the result can be more serious
The reading frame of the gene is affected

Question 15

Nucleotide insertion (Frameshift)

Answer 15

Pushes the rest of the nucleotides back along the sequence

Question 16

Nucleotide deletion (Frameshift)

Answer 16

Brings the rest of the nucleotides forward along the sequence