HTHSCI 1LL3 Lecture 11: Translation
6 Mar 2017
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Document Summary
It is usually the 3rd base that is different in the codons, specifying the same amino acid: the third o(cid:374)e does(cid:374)"t (cid:272)ause (cid:373)utatio(cid:374) if they (cid:272)ha(cid:374)ge. Mutations: mutations can arise as a result of dna damage or incorrect incorporation of bases. Types of mutations: point a single base change, silent a change that specifies the same amino acid, missense a change that specifies a different amino acid, nonsense a change that produces a stop codon. Insertion an addition of one or more bases: deletion a loss of one or more bases. Insertions & deletions: these are usually the cause of frameshift mutations, frameshifting can also result in a premature stop codon, producing a non-functional. Initiation involves formation of a complex between the methionyl-trna, initiation factors the mrna, and the small ribosomal subunit: the large subunit binds to complete the ribosome which has 2 binding sites for trnas, the peptidyl and aminoacyl.
