MBG 1000 Lecture Notes - Lecture 5: Stop Codon, Dna Polymerase, Dna Replication

• School: University of Guelph
• Department: Molecular Biology and Genetics
• Course: MBG 1000
• Professor: Georgevander Merwe

Document Summary

*release factor binds to the stop codon, because the stop codon has no trna. A change in the nucleotide sequence of dna. Source of genetic variation (origin can be neutral, beneficial or detrimental) Origin: either spontaneous (dba replication errors) or induced mutations (environmental impact such as a free radical damage or uv/chemical damage) Changes in the nucleotide sequence as a result of errors in dna replication: Dna polymerase replicates dna: proof-reading activity can correct its errors, dna repair mechanisms. Error rate: 1-12 gametes out of a million will have a mutation in some gene. Micro scale: (only 1-2 nucleotides affected at a time) point mutations or frame shift mutations. Involves multiple genes; often large fragments of dna (deletion, duplication, inversion, insertion, translocation) (pictures on page 9) Point mutations: involves the substitution of one nucleotide base for another (spontaneous or induced) Frame shift mutations: insertion or deletion of nucleotides into a gene to alter the reading frame of the gene)