Biotechnology

Page
6

Slide 40

One method of introducing recombinant DNA into eukaryotic cells is electroporation, applying a brief electrical pulse to create temporary holes in plasma membranes

Alternatively, scientists can inject DNA into cells using microscopically thin needles

Once inside the cell, the DNA is incorporated into the cell’s DNA by natural genetic recombination

Slide 41

Amplifying DNA in Vitro: The Polymerase Chain Reaction (PCR)

The polymerase chain reaction, PCR, can produce many copies of a specific target segment of DNA

A three-step cycle—heating, cooling, and replication—brings about a chain reaction that produces an exponentially growing population of identical DNA molecules

Slide 42

Fig. 20-8

5

Genomic DNA

TECHNIQUE

Cycle 1 yields

2

molecules

Denaturation

Annealing

Extension

Cycle 2 yields

4

molecules

Cycle 3 yields 8

molecules; 2 molecules (in white boxes) match target sequence

Target sequence

Primers

New nucleo- tides

3

3

3

3

5

5

5

1

2

3

Slide 43

Fig. 20-8a

5

Genomic DNA

TECHNIQUE

Target sequence

3

3

5

Slide 44

Fig. 20-8b

Cycle 1 yields

2

molecules

Denaturation

Annealing

Extension

Primers

New nucleo- tides

3

5

3

2

5

3

1

Slide 45

Fig. 20-8c

Cycle 2 yields

4

molecules

Slide 46

Fig. 20-8d

Cycle 3 yields 8

molecules; 2 molecules (in white boxes) match target sequence

Slide 47

Concept 20.2: DNA technology allows us to study the sequence, expression, and function of a gene

DNA cloning allows researchers to

Compare genes and alleles between individuals

Locate gene expression in a body

Determine the role of a gene in an organism

Several techniques are used to analyze the DNA of genes

Slide 48

Gel Electrophoresis and Southern Blotting

One indirect method of rapidly analyzing and comparing genomes is gel electrophoresis