DNA Sequencing 8.2

Polymerase Chain Reaction (PCR) a direct method of making many copies of a DNA sequence exponential increase because each cycle doubles the number of DNA molecules useful in forensics, medical diagnosis and genetic research because a small amount of DNA can be amplified

Taq polymerase from Thermus aquaticus (type of bacteria that live in hot springs) is not denatured at the high temperatures needed in PCR works optimally at 72ºC

PCR Animations Look at step-by-step animation of PCR process first: Then this excellent interactive “virtual lab”:

Gel Electrophoresis

a method of separating molecules based on size DNA migrates through the gel towards a positive electrode smaller fragments move faster through the gel, causing separation by size DNA fragments can be seen by using a stain such as ethidium bromide

Gel Electrophoresis

Excellent interactive animation of gel electrophoresis: Slideshow with focus on scientists and history of gel electrophoresis: oresis.html

DNA Sequencing chain termination method (Sanger dideoxy method) was developed in the 1970s by Frederick Sanger Human Genome Project used 2 methods of sequencing, both involving the Sanger method

Deoxy- vs. Dideoxy

Sanger method Excellent simple narrated animation: EstructuraDelGenoma/animaciones/sec uencia.swf

So you’ve sequenced it… …what can you do with the data? structural genomics functional genomics bioinformatics

Interesting findings… can sequence a gene and then use computer to find similar sequences in the same genome or in other genomes have discovered many genes of unknown function unexpected degree of similarity between different organisms (e.g., yeast & humans)

$1000 Genome Initiative it currently takes about 8 days and $ to sequence the human genome the race is on to be able to sequence the genome for less than $1000 nanopore sequencing

DNA Microarray

allows scientists to pinpoint the functions of specific genes the expression of thousands of genes in a particular cell can be identified simulaneously

Microarray microarray or gene chip can hold from 10 to 2.1 million DNA samples (probes) could be used to compare a “normal” cell with a cancerous cell isolate mRNA from both cells; synthesize labelled cDNA; denature and place on microarray

DNA Microarray To read the results: RED shows gene is expressed in experimental (cancerous) cell GREEN show gene is expressed in normal cell YELLOW shows gene is expressed in both cells

Microarray Animation Excellent interactive animation with simplified explanation of process: omics/chip/chipQ.html