sequencing the genome
- Created by: vezting
- Created on: 23-02-16 17:30
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- sequencing gene and genomes
- DNA sequencing
- 1: this mixture is split into 4 test tubves
- single-stranded DNA template to be sequenced
- DNA polymerrase to join nucleotides together
- lots of DNA primer
- many free floating nucleotides
- a fluorescenty labelled modified nucliotide, after attaching to DNA strand, no more nucleotides attach after it.
- 2: tubes undergo PCR. the strands are different lengths as they terminate at different points
- 3:DNA fragments in each tube seperated by gel electrophoresis and visualised under UV light because of fluorescent label.
- 4: smallest nucleotide (1) is at the bottom of the gel, each band after this represents one nucleotide added, so reading upwards you can get the sequence
- 1: this mixture is split into 4 test tubves
- genome sequencing
- chain termination method (DNA sequencing) can only be used for fragmetns up to 750bp long
- to sequence whole genome it needs to be chopped into smaller bits then put back together
- 1: genome cut into 100,000 bp long peices using restriction enzymes
- 2: fragments inserted into BACs
- 3: BACs inserted into bacteria
- 4: bacteria divide, creating colonies of cloned cells which all contain specific DNA, making a genomic DNA library
- 5: DNA is extracted from each colony and cut using restriction enzymesproducing overlapping peices of DNA
- 6: each peice of DNA is sequenced using chain termination method.
- 7: the peices are put back in order to give full sequence from that BAC, then DNA fragments from all BACs are put in order for entire genome
- chain termination method (DNA sequencing) can only be used for fragmetns up to 750bp long
- comparing genomes
- we want to compare between different species to help us understand evolutionary relationships
- closely related species will share more DNA than those less closely related
- comparing across species help us understand how genes react during development and how theyre controlled
- closely related species will share more DNA than those less closely related
- comparing genome within species helps trace early human migration
- is also used to study human genetic diseases
- sciensits also compare within species to develop medical treatmentments for particular genotypes
- we want to compare between different species to help us understand evolutionary relationships
- DNA sequencing
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