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DNA Technology

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Copying DNA: PCRCopying DNA: PCR• Polymerase Chain ReactionPolymerase Chain Reaction• Gene Amplification • A method of making many copies of a piece of DNA

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PCR: Copying DNAPCR: Copying DNA

•DNA, nucleotides, buffers, “taq” polymerase, and two primers are placed in a small test tube

• taq polymerasetaq polymerase can work at very high temps

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PCR: Step 1PCR: Step 1

•The DNA is heatedDNA is heated (80oC), the two strands separate

• PrimersPrimers match with complementary bases

•Taq pol. begins adding new nucleotides (5’->3’)

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PCR: Step 2PCR: Step 2

•The tube is cooled the DNA strands together

•Cycle repeated to make several copies

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PCRPCR

Large amounts of DNA can be made Large amounts of DNA can be made from a small starting samplefrom a small starting sample

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Cloning

Just a gene vs. whole organims

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Bacterial plasmids in gene cloning

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Cloning a gene• Requires:

– Plasmid (cloning vector), restriction enzymes, and gene of interest

• DNA ligase attaches the sticky ends of DNA fragments together

• Chimeric DNA made!

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Cloning Cloning an an

organismorganism• A body cellbody cell from one organism and an egg cellegg cell from another are fused

• The resulting cell divides divides like a normal like a normal embryoembryo

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Cloning “Dolly”Cloning “Dolly”

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Cutting DNACutting DNA• Restriction enzymesRestriction enzymes cut DNA at specific sequences

• Useful to divide DNA into manageable fragmentsmanageable fragments

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Electrophoresis•DNA can be separated based on size and chargesize and charge

•The phosphate phosphate groupsgroups are negativelynegatively charged

•DNA is placed in a gelgel and electricityelectricity is run through

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Electrophoresis• Negative DNANegative DNA moves toward the positive end

• SmallerSmaller fragments move farther and fasterfarther and faster

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Electrophoresis