Mutations and Variation

If only one nucleotide is affected, what is the mutation described as?

A point mutation

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Name the 3 types of point mutation

Insertion, deletion or substitution

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What are the 2 frameshift mutations?

Insertion and deletion

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Describe a substitution mutation

Where one or more nucleotides (or base pairs) have been replaced with another nucleotide or base pair, in a gene

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Describe an insertion mutation

It is where a base pair or nucleotide has been inserted into the gene

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Describe a deletion mutation

Where one or more nucleotides (or base pairs) have been deleted/removed in a gene

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Describe how a mutation can lead to there been no effect on the phenotype

It can have no effect on the phenotype due to the fact that the change will not have affected the change in the protein's function

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Describe how a mutation can have a damaging effect on an organism's phenotype

The change in amino acid sequence can effect the way the R-groups interact and effect the function of the enzyme (eg enzyme active site), there for they can no longer carry out their function

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Describe how a mutation can be beneficial to an organism's phenotype

It can be possible that the protein synthesised results in new and useful characteristics (eg Mutation in cell surface membrane protein, protecting it from HIV)

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What is a mutagen?

A chemical, physical or biological agent which increases the rate of mutation or causes mutation

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Give an example of a physical mutagen and what it does

Xray- breaks one or both strands (some breaks can be repaired but mutations occur in the process)

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Give an example of a chemical mutagen and what it does

Deaminating agent- Chemically alters the bases in DNA (eg changing cytosine and uracil)

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Give an example of a biological mutagen and what it does

Virus- Insertion of viral DNA into genome changing the base sequence

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Describe how some are able to digest lactose

The ability to digest lactose is a beneficial mutation, as we weren't able to originally able to digest it.

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Whats the difference in gene mutation and chromosome mutations?

Gene mutation occurs in single genes or sections of DNA where as chromosome mutation can affect the whole chromosome or a number of chromosomes

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Describe the change in chromosome structure when deletion happens

A section of the chromosome breaks off and is lost

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Duplication

Sections of the chromosome gets duplicated on it

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Translocation

A section of the chromosome breaks off and joins another nonhomologous chromosome

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Inversion

When a section of a chromosome breaks off, flips and rejoins

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Mutations and Variation

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