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Lecture 41

Genetic Variation. Already know that genes have different alleles - how do these arise?Process of mutation - an alteration/change in the genetic materialOrigin:Internal (e.g. mistakes during replication of DNA)External (e.g. radiation, chemicals)Most mutations have no effect or are harmful. Typ

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Lecture 41

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    1. Lecture 41 Prof Duncan Shaw

    2. Genetic Variation Already know that genes have different alleles - how do these arise? Process of mutation - an alteration/change in the genetic material Origin: Internal (e.g. mistakes during replication of DNA) External (e.g. radiation, chemicals) Most mutations have no effect or are harmful

    3. Types of mutation Non-coding - not in part of gene that codes for protein - either no effect, or effect on gene expression Coding: Synonymous - same amino acid Missense - different amino acid Nonsense - premature stop codon Frameshift (deletion or insertion of bases) - change in structure of protein

    4. Mutagenesis Mutagens are chemicals (or radiation, etc.) that cause heritable alterations in DNA sequence in somatic and germ cells New mutations are rare - most genetic characteristics are due to inheritance from parents Teratogens are chemicals (or radiation, etc.) that affect development of the embryo/foetus and may cause congenital abnormalities (e.g. thalidomide)

    5. The human genome Its size is 3 x 109 bp (3000Mb) for a single copy Contains 23 pairs of chromosomes About 35,000 genes About 1 million sites in the DNA that vary between individuals (most with no effect on phenotype)

    6. Meiosis and Recombination

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