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Presentation on theme: "Mutations."— Presentation transcript:

1 Mutations

2 Protein synthesis summary
DNA A C T G C G A U mRNA transcription nucleus Gly Ser Phe Trp PROTEIN translation Cytoplasm: ribosome

3 Definition: A mutation is…
A change in the arrangement of bases in an individual gene or in the structure of the chromosome (which changes the arrangement of genes).

4 Frequency and repair of mutations
Mutations can occur in gametes and somatic cells. Chance of mutation is between 2-30 x 10-7 Faulty DNA can be repaired by specific enzymes. Unrepaired mutations will affect the new proteins being synthesised

5 Point mutations are caused by:
Changes in an individual gene due to miscopying of one or more nucleotides. Deletion or insertion of a nucleotide results in a frameshift: C A T G C G A T C A G A T Codon 1 Codon 2 Codon 3 Codon 4 Val Tyr Arg Ala Ser Leu

6 Point mutations T A C G T G A A A T C G G C A T Met His Phe Leu Ala
Substitution mutations result in a change of one base: T A C G T G A A A T C G G C A T Met His Phe Leu Ala Val

7 Chromosomal mutations
Gene deletion: A B C D E Gene duplication: C D B A E E C D B A

8 Chromosome mutations B A C D E B A C D E W X Z Y Inversion:
Translocation: B A C D E W X Z Y

9 Whole-chromosome mutations
An entire chromosome is lost or repeated during cell division. Example: Downs syndrome is caused by having an extra chromosme 21.

10 The effect of mutations
Production of new/superior protein: Results: gain of reproductive advantage Neutral mutation: Result: No change Production of inferior or no protein: Result: Fatal and/or disease causing.

11 Causes of mutations Mutagens such as: X-rays ionising radiation chemicals

12 Summary Define the term: translocation somatic duplication deletion
mutation insertion inversion Down’s syndrome mutagen


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