Muations

Question 1

What is a mutation

Answer 1

A change in the quantity or the base sequence of the DNA of an organism

Question 2

What’s a gene mutation

Answer 2

Any change to one or more nucleotide bases, or a change in the sequence of the bases, in DNA

Question 3

If there are any changes to one or more bases in the DNA triplets, what could this result in

Answer 3

in a change in the amino acid sequence of the polypeptide

Question 4

What are the types of gene mutation

Answer 4

Base substitution

Base deletion

Question 5

What is the substitution of bases

Answer 5

When one base is substituted with another

Question 6

What is the deletion of bases

Answer 6

One base is deleted

Question 7

What are chromosome mutations

Answer 7

Changes in the structure or number of whole chromosomes

Question 8

What are the two forms of chromosome mutations

Answer 8

Changes in the whole sets of chromosomes, it occurs when organisms have 3 or more sets of chromosomes rather then the normal 2. This condition is called polyploidy (mostly in plants)

Changes in the number of individual chromosomes - sometimes homologous pairs of chromosomes fail to separate during meiosis ( non-disjunction) and usually results in a gamete having either one more of one fewer chromosomes.

Question 9

Explain why a deletion gene mutation is more likely to result in a Change to an organism than a substitution gene mutation

Answer 9

In deletion all codons after the deletion add affected. Therefore most amino acids coded for by these codons will be different and the polypeptide will be significantly affected. In a substitution, only a single codon, and therefore a single amino acid, will be affected. The effect of the polypeptide is likely to be less severe

Question 10

Explain why a mutation transcribed onto mRNA may not result in any change to the polypeptide it codes for.

Answer 10

The mutation may result from the substitution of one base in the mRNA with another. Although the codon affected will be different, as the genetic code is degenerate, the changed codon may still code for the same amino acid. The polypeptide will be unchanged and there will be no effect

Question 11

Explain why errors in dna replication can be far more damaging then errors in transcription

Answer 11

These errors may be inherited and may therefore have permanent affect on the whole organism. Errors in transcription usually affect only specific cells, are temporary and not inherited. They are therefore less damaging