gene mutation

Question 1

what does the term ‘mutation’ mean?

Answer 1

mutation is defined as the change in the sequence of DNA, number of chromosomes, or structure of chromosomes in an organism

Question 2

what is a gene mutation?

Answer 2

a gene mutation is the change in the sequence of nucleotides of a gene

Question 3

what may change in a gene mutation?

Answer 3

a gene mutation may change the sequence of amino acids in a polypeptide chain

Question 4

what does a gene mutation affect?

Answer 4

this may affect the structure and function of the protein, and thus affecting the characteristic (phenotype) of the organism

Question 5

what can a gene mutation give rise to?

Answer 5

a gene mutation can give rise to new alleles which code for potential new traits, and also result inheritable disease

Question 6

what are the 3 types of gene mutation?

Answer 6

1. substitution
2. insertion
3. deletion

Question 7

what is the definition of ‘substitution mutation’?

Answer 7

a substitution mutation is defined as when 1 or more nucleotide(s) in the nucleotide sequence of the gene is or are replaced by other nucleotides

Question 8

what is the definition of ‘insertion mutation’

Answer 8

an insertion mutation occurs when 1 or more nucleotide(s) is or are added into the nucleotide sequence of the gene

Question 9

what is the definition of ‘deletion mutation’?

Answer 9

a deletion mutation occurs when 1 or more nucleotides(s) is or are removed form the nucleotide sequence of the gene

Question 10

what is the most common type of gene mutation?

Answer 10

SUBSTITUION MUTATION

Question 11

what are the 3 possible outcomes for a substitution mutation, depending on the position of the nucleotide affected?

Answer 11

1. silent mutation
2. missense mutation
3. nonsense mutation

Question 12

why does the substitution of 1 or more nucleotides may result in silent mutation?

Answer 12

this is because the genetic code is degenerate, whereby there are many different codons can still code for the same amino acid

Question 13

why is the function of the protein unaffected by a silent mutation?

Answer 13

this is because the silent mutation results in no change of codon in the mRNA, resulting in the same amino acid with the same R group upon translation

hence, there is no change in the amino acid sequence of the polypeptide chain

therefore, the folding of the polypeptide chain into its precise, compact 3 dimensional conformation is not affected, and properties of the protein are unaffected.

as a result, the protein remains functional

Question 14

what is the effect of a substitution mutation (formation of different amino acid(s)) on the mRNA sequence?

Answer 14

the nucleotide change in the gene will change the mRNA sequence upon translation

Question 15

what is the effect of a substitution reaction (formation of different amino acid) on the mRNA?

Answer 15

this causes the codon(s) in the mRNA to change

Question 16

what is the effect of the substitution reaction (formation of different amino acid) on the amino acid sequence of the protein?

Answer 16

this results in a different amino acid with a different R group upon translation, whereby, for example, a hydrophilic amino acid could be replaced by a hydrophobic amino acid

hence, the amino acid sequence of the polypeptide chain is now different

Question 17

what is the effect of a substitution mutation (formation of different amino acid) on protein folding and its property?

Answer 17

the folding of the polypeptide chain into its precise 3 dimensional conformation is now affected, hence the property of the protein is now different

Question 18

what is the effect of a substitution mutation (formation of different amino acid) on the structure of the protein?

Answer 18

the protein now becomes non-functional