Biotechnology

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Gene used to alter bacteria for cleaning up toxic waste

Protein dissolves blood clots in heart attack therapy

Human growth hor- mone treats stunted growth

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4

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Slide 8

Fig. 20-2a

DNA of chromosome

Cell containing gene of interest

Gene inserted into plasmid

Plasmid put into bacterial cell

Recombinant DNA (plasmid)

Recombinant bacterium

Bacterial chromosome

Bacterium

Gene of interest

Plasmid

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Slide 9

Fig. 20-2b

Host cell grown in culture to form a clone of cells containing the “cloned” gene of interest

Gene of Interest

Protein expressed by gene of interest

Basic research and various applications

Copies of gene

Protein harvested

Basic research on gene

Basic research on protein

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Recombinant bacterium

Gene for pest resistance inserted into plants

Gene used to alter bacteria for cleaning up toxic waste

Protein dissolves blood clots in heart attack therapy

Human growth hor- mone treats stunted growth

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Slide 10

Using Restriction Enzymes to Make Recombinant DNA

Bacterial restriction enzymes cut DNA molecules at specific DNA sequences called restriction sites

A restriction enzyme usually makes many cuts, yielding restriction fragments

The most useful restriction enzymes cut DNA in a staggered way, producing fragments with “sticky ends” that bond with complementary sticky ends of other fragments

Animation: Restriction Enzymes

Slide 11

DNA ligase is an enzyme that seals the bonds between restriction fragments

Slide 12

Fig. 20-3-1

Restriction site

DNA

Sticky end

Restriction enzyme cuts sugar-phosphate backbones.

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Slide 13

Fig. 20-3-2

Restriction site

DNA

Sticky end

Restriction enzyme cuts sugar-phosphate backbones.

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DNA fragment added from another molecule cut by same enzyme. Base pairing occurs.

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One possible combination

Slide 14

Fig. 20-3-3

Restriction site

DNA

Sticky end

Restriction enzyme cuts sugar-phosphate backbones.

5

3

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One possible combination

Recombinant DNA molecule