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DNA Technology

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Genetic Engineering

  • The process of manipulating genes for practical purposes.
  • Because all DNA has the same basic structure, we can cut and paste genes from one organism into the chromosome of another organism.

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Recombinant DNA

DNA made from two or more different organisms

(Connecting DNA from different sources)

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Gene of Interest

The gene to be inserted

(Codes for the trait we want expressed)

Vector

The DNA into which we will insert the gene of interest.

*Bacterial DNA makes a great vector*

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Steps in Genetic Engineering

Step 1: Cut gene of interest & vector with restriction enzymes.

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transformed�bacteria

gene from�other organism

Bacterial

DNA

cut DNA

recombinant�plasmid

vector

glue DNA

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Step 2: Connect DNA fragments together.�

  • How do we “Glue” sticky ends together?
  • DNA Ligase – An enzyme used to connect sticky ends of DNA fragments

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How do we get more of these transformed bacteria?

Single Transformed�Bacteria

Feed them and they will reproduce!

Binary Fission

Copy DNA and split = “Cloning”

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So, Transformation is like:

  • Word Processing – Cut, Paste, Copy
  • Cut
    • Restriction enzymes
  • Paste
    • Ligase
  • Copy
    • Plasmid replication
      • Binary Fission

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Many Uses of Restriction Enzymes…

Now that we can cut DNA…

  • We can COMPARE it!
    • Why?
      • Forensics
      • Medical diagnostics
      • Paternity
      • Evolutionary relationships
      • and more…

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Comparing DNA

  • Gel Electrophoresis – A method of separating DNA fragments by size using an electrical field.
    • DNA is negatively charged so in an electrical field it moves toward the positive side
    • Small pieces travel faster/farther than larger pieces.

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DNA → → → → → → → →

“Swimming through Jello”

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Gel Electrophoresis:

Longer fragments

Shorter fragments

Completed gel

DNA &�Restriction enzyme

Electrical current

Restriction Fragments

wells

gel

power

source

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negative

positive

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DNA Fingerprint

  • A picture of the product of gel electrophoresis.

Because each individual’s DNA is unique, each person has a unique DNA fingerprint

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DNA Fingerprint Uses: Forensics

Comparing DNA sample from crime scene with suspects & victim

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S1

DNA

↓

S2

S3

V

Suspects

Crime �scene �sample

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Process used to repeatedly copy the same piece of DNA many times.

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Helpful in magnifying DNA from:

Crime scenes

Fossil remains

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PCR

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Human Genome Project

3.2 billion base pairs in the human genome

  • Only 1-1.5% codes for proteins
  • Only about 30,000 to 40,000 genes

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Genetic Engineering

  • Why would we want to do this?
  • To Create Drugs & Vaccines:
    • Create organisms (Animals or bacteria) that produce human proteins
  • Bacteria that produce:
    • Factor VIII-protein that promotes blood clotting to treat Hemophilia
    • Growth hormones
    • Production of human insulin by bacteria
  • To create better agricultural products:
      • Delayed ripening & resistance to spoilage
        • Anti-softening tomatoes
      • Protect crops from insects: BT corn
        • Corn produces a bacterial toxin that kills corn borer (caterpillar pest of corn)
      • Herbicide resistance: Cotton
        • Bacterial gene resistant to weed-killing herbicides