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Description
Flashcards by 007842-Stuart Denton, updated more than 1 year ago
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Created by 007842-Stuart Denton
almost 8 years ago
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| Question | Answer |
| Mutation | Is a random change to the genetic material. Some involve changes to the structure or number of chromosomes. |
| Types of gene mutation | Mitotic division - Are somatic mutations and are not passed to offspring. Meiosis mutations- gamete formation maybe inherited by offspring. |
| Two Classes of Mutation | POINT MUTATION: one base pair replaces another INSERTION OR DELETION MUATATION: one or more nucleotides are in/del from a length of DNA |
| Point Mutations | Three Types: Silent Missense Nonsense |
| Indel mutations | Both insertions or deletions that cause a frameshift. |
| Silent Mutation | Mutations can be reduced because amino acids have more than one base triplet code. When a triplet code CHANGES but still codes for the SAME amino acid. |
| Missense Mutations | A CHANGE to the base triplet sequence that leads to a change in the amino acid sequence in a protein. |
| Nonsense Mutations | A point mutation may alter the base triplet, so that it cause the sequence to terminate. Especially destructive- Duchenne Muscular Dystrophy |
| Frameshift | If a nucleotide base pairs are inserted in the gene or deleted from the gene because the code is non-overlapping, read in 3's and following bases are altered. |
| Expanding triple nucleotide repeats | In an E.T.N.R the number of amino acids in the triplet increases at meiosis and again from generation to generation. Huntington disease. |
| Beneficial Mutations | Help drive evolution through natural selection. Different alleles of a particular genes are expressed because of mutation. Eye colour Skin colour |
| Regulation of Gene expression at transcription level in Prokaryotic cells | Enzymes that catalyse the metabolic reactions are synthesised at a constant rate. Enzymes that may only be needed under specific conditions are synthesised at varying rates. |
| The lac Operon | E.coli normally metabolises glucose as respiratory substrate. When lactose is present, lactose induces the production of two enzymes: Lactose permease B-galactosidase |
| Lac Operon structure | Consists of a length of DNA, 6000 base pairs long. Contains Operator region LacO, structural genes LacZ and LacY. Which code for B-galactosidase and lactose permease. |
| Lac Operon Function | When regulatory gene is expressed, the repressor protein produced binds to the operator preventing RNA polymerase from binding to promoter region. When lactose is present, it binds to LacI repressor protein, RNA polymerase can then bind to promoter region. |
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