BIOTECH!

Figure 20.17 DNA fingerprints from a murder case

Figure 20.0 DNA sequencers

Biotechnology

• Biotechnology is the manipulation of organisms or their components to provide useful products or perform practical tasks

DNA Cloning

• Produces gene-sized pieces of DNA in multiple identical copies.

• Plasmids, circular DNA pieces separate from the main chromosome, are used

• Human growth hormone is mass-produced this way

Figure 20.1 An overview of how bacterial plasmids are used to clone genes

Restriction Enzymes

• Cut up DNA into fragments after a certain base sequence is recognized

Figure 20.2 Using a restriction enzyme and DNA ligase to make recombinant DNA

Figure 20.4 Using a nucleic acid probe to identify a cloned gene

Polymerase Chain Reaction

• Also called PCR.

• Method of copying small samples of DNA multiple times. Involves heating of DNA strands (denaturing) and cooling. Nucleotides and primers in solution initiate replication.

Figure 20.7 The polymerase chain reaction (PCR)

Gel Electrophoresis

• Used to separate small DNA fragments (typically treated first with restriction enzymes) on the basis of their mass and charge

• Heavier fragments travel more slowly down the gel than lighter fragments

Figure 20.8 Gel electrophoresis of macromolecules

Figure 20.9 Using restriction fragment patterns to distinguish DNA from different alleles

Southern Blotting

• Enables researchers to detect whether certain DNA sequences exist in a sample.

• Bands from electrophoresis are “blotted” onto a special paper, and treated with a radioactive DNA single strand.

• The radioactive strand binds with any complementary strand

Figure 20.10 Restriction fragment analysis by Southern blotting

Sanger Method

• Used to determine the nucleotide sequence of DNA.

• DNA fragments and primers, and special modified nucleotides (dd) used.

• DNA sequence can be read off of gel.

Figure 20.0 DNA sequencers

Figure 20.12 Sequencing of DNA by the Sanger method (Layer 1)

Figure 20.12 Sequencing of DNA by the Sanger method (Layer 2)

Figure 20.12 Sequencing of DNA by the Sanger method (Layer 3)

Figure 20.12 Sequencing of DNA by the Sanger method (Layer 4)

Figure 20.12 Sequencing of DNA by the Sanger method (Layer 4)

ddATP ddCTP ddTTP ddGTP

Figure 20.12 Sequencing of DNA by the Sanger method (Layer 4)

ddATP ddCTP ddTTP ddGTP

Nucleotide Sequence: ATCAGTAGTGCTOriginal DNA Sequence: TAGTCATCACGA

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Table 20.1 Genome Sizes and Numbers of Genes

Figure 20.x1a Laboratory worker reviewing DNA band pattern

Macroorganism Cloning

• Nucleus of an adult cell is removed, placed into an egg cell whose nucleus was removed.

• Egg cell is stimulated to start dividing.

• Organism is a clone of its mother.