Studying genomes
- Created by: Steff06
- Created on: 13-05-16 12:24
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- Studying genomes
- Methods:
- Genome sequencing + comparative genome mapping.
- Genetic fingerprinting
- Gene therapy.
- Genetic engineering.
- Natural processes:
- DNA cut into smaller fragments using restriction endonuclease
- Fragments separated using electrophoresis.
- Replicated many times by polymerase chain reaction (PCR).
- DNA fragments analysed to give specific base sequence.
- DNA fragments sealed together using DNA ligase.
- DNA probes used to locate specific sequences on fragments.
- Genomic age:
- Genes code for proteins and polypeptides.
- This coding DNA forms a small part of DNA. Most is non-coding DNA.
- Sequencing can only operate on 750 base pairs so genome must be broken up and sequenced in sections.
- Genomes mapped. Known info e.g. location of microsatellites used.
- Samples of genes sheared into smaller sections of 100,000 base pairs (shotgun approach).
- Sections put in separate Bacterial Artificial Chromosomes (BAC's). Transferred to E.coli cells.
- Samples of genes sheared into smaller sections of 100,000 base pairs (shotgun approach).
- Sequencing a BAC section:
- 1. Cells with specific BAC's taken and cultured. DNA extracted and restriction endonucleases used to cut into smaller fragments.
- Different restriction enzymes used to produce different fragment types.
- 2. Fragments separated by electrophoresis.
- 3. Each fragment sequenced using automated process.
- 4. Programmes compare overlapping regions from cuts made by different restriction endonucleases.
- Done to reassemble whole BAC segment sequence.
- 1. Cells with specific BAC's taken and cultured. DNA extracted and restriction endonucleases used to cut into smaller fragments.
- Comparing genomes:
- Comparing sequences across range of organisms = Comparative base mapping
- Applications to identification of genes in proteins and their importance.
- Can compare DNA of different species to show evolutionary relationships.
- Modelling effects of changes of DNA.
- Comparing genomes from pathogenic and similar non-pathogenic organisms.
- DNA of individuals analysed to reveal mutant alleles or increased risk of disease.
- Methods:
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