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Mutations. A. C. A. A. T. C. C. A. G. T. A. G. transcription. nucleus. A. A. C. G. C. U. U. U. U. U. G. G. mRNA. ribosome. translation. Cytoplasm:. Ser. Trp. Phe. Gly. PROTEIN. Protein synthesis summary. DNA. Definition: A mutation is….
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A C A A T C C A G T A G transcription nucleus A A C G C U U U U U G G mRNA ribosome translation Cytoplasm: Ser Trp Phe Gly PROTEIN Protein synthesis summary DNA
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).
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
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: T C A G A T A C A T G C G Codon 4 Codon 3 Codon 1 Codon 2 Leu Ser Arg Ala Tyr Val
Point mutations • Substitution mutations result in a change of one base: T A C G G C A T T A C G T G A A Met His Phe Leu Ala Val
A B A A B B C C C D D D E E Chromosomal mutations • Gene deletion: C D E • Gene duplication:
Y X A A W Z B B C D Chromosome mutations • Inversion: C D E • Translocation: E
Whole-chromosome mutations • An entire chromosome is lost or repeated during cell division. • Example:Downs syndrome is caused by having an extra chromosme 21.
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.
Causes of mutations • Mutagens such as:X-raysionising radiationchemicals
translocation duplication somatic deletion mutation insertion Down’s syndrome inversion mutagen Summary • Define the term: