Download 21.8 Recombinant DNA

21.8 Recombinant DNA
DNA can be used in
• genetic engineering that
permits scientists to cut and
recombine DNA fragments
to form recombinant DNA.
• the identification of a
person by examining bands
on film that represent DNA
fingerprints.
Learning Goal Describe the preparation and uses of
recombinant DNA.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Recombinant DNA
In preparing recombinant DNA,
• a DNA fragment from one organism is combined
with DNA from another.
• restriction enzymes are used to cleave a gene from
a foreign DNA and open DNA plasmids in
Escherichia coli.
• DNA fragments are mixed with the plasmids in E.
coli and the ends are joined by ligase.
• the new gene in the altered DNA produces protein.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Recombinant DNA
Recombinant DNA is
formed by placing
a gene from another
organism in a plasmid
DNA of a bacterium.
This causes the
bacterium to produce
a nonbacterial protein.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Products of Recombinant DNA
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Polymerase Chain Reaction
A polymerase chain reaction (PCR)
• made it possible to produce multiple
copies of a DNA in a short time.
• separates the sample DNA strands
by heating.
• mixes the separated strands with
enzymes and nucleotides to form
complementary strands.
• is repeated many times to produce a
large sample of the DNA.
Each cycle of the polymerase chain reaction doubles
the number of copies of the DNA section.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Genetic Testing
Polymerase chain reaction (PCR)
• allows screening for defective genes.
• can be used to screen for genes associated with
breast cancer.
Multiple defects in two known breast cancer genes,
called BRCA1 and BRCA2, correlate to a higher risk
of breast cancer.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
DNA Fingerprinting
In DNA fingerprinting,
• restriction enzymes cut a
DNA sample into smaller
fragments (RFLPs).
• the sample is placed on a
gel and separated using
electrophoresis.
• the banding pattern on the
gel is called a DNA
fingerprint and is unique to
each individual.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
The Human Genome
The Human Genome Project
• was completed in 2003 and showed that our DNA is
composed of 3 billion bases and 21 000 genes coding
for protein, which represents only 3% of the total DNA.
• has since identified stretches of DNA that code for
other RNA molecules.
Much of our DNA
• regulates genes and serves as recognition sites for
proteins.
• has been assigned a function leading to understanding
errors in DNA replication, transcription, or regulation.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.