Transcript Lecture 23: Powerpoint

Biology 102
Biotechnology
Lecture outline
What is biotechnology?
 Goals of biotechnology
 How does genetic recombination occur
in nature?
 How does genetic engineering occur in
the lab?
 Application of biotechnology
 Focus on GMOs (modified crops and
animals)

What is biotechnology?


Any commercial use or alteration of
organisms, cells and biological molecules to
achieve specific, practical goals.
Examples (in long use)



Selective breeding
Use of yeast to make wine
Current techniques

Genetic engineering: modification of genetic material
to achieve specific goals
Goals of Biotechnology



To understand more about the processes of
inheritance and gene expression
To provide better understanding & treatment
of various diseases, particularly genetic
disorders
To generate economic benefits, including
improved plants and animals for agriculture
and efficient production of valuable
biological molecules

Example: Vitamin A fortified engineered rice
(Chapter-opening case study)
Methods of Biotechnology:
Examples

“Older” techniques
Selective breeding
 Use of yeast to make wine


Current techniques

Genetic engineering: modification of genetic
material to achieve specific goals
How does DNA Recombination
occur in nature?
Sexual reproduction
 Bacterial recombination
 Transfer by viruses

Recombination in Bacteria
(a)
Bacterium
Plasmid
(b)
transferred
to new host
(c)
DNA fragments
transferred
to new host
Chromosome
Plasmid
1 µm
Plasmids allow
bacteria to grow in
novel environments
Plasmid replicates
in cytoplasm
DNA fragment
incorporated into
chromosome
Transfer of genes by viruses
Genetic engineering in the lab

Create a “DNA” library

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Fragments from entire genome end up in different
bacterial colonies
Most fragments will not end up being useful
Some may have the gene(s) you want
Getting the gene you want is like finding a needle in a
haystack!
First step: Cutting up the DNA

Gives you workable fragments that can be
incorporated into bacteria
Cutting DNA with restriction enzymes

Restriction enzymes cut DNA in
specific locations

Example: The restriction enzyme EcoRI
 recognizes
the sequence GAATTC
 Cuts the sequence in half anywhere encountered

Different restriction enzymes cut in
different places

Creating a DNA
library

Note that plasmid
vector and desired
DNA are cut with
same restriction
enzyme, so
complementary
base pairing occurs

Create different
bacterial colonies
with different
fragments
Finding the genes of interest

Restriction length polymorphisms

Tell you whether two individuals are the same or
different for a particular fragment in your library


IF individuals differ for sequence recognized by the restriction
enzyme, then they will be cut differently
Search for these polymorphisms for people known to
differ for different traits
Gel electrophoresis
DNA fingerprinting
Finding genes of interest (cont.)

Use a DNA probe: short sequence of single-strand
DNA that is part of the sequence of interest


Useful only if you already know the sequence you are looking
for!
Can use genes from one organism to find similar genes in
another organism
Finding genes of interest (cont.)

Identify genes on basis of gene product
(i.e. the protein they make)

Can transcribe and translate the gene inside
the host bacterium
Applications of biotechnology
DNA fingerprinting (identification)
 Transgenic crops and animals (GMOs)
 Production of therapeutic proteins
 Models of human genetic diseases
created in other organisms
 Genetic testing
 Gene therapy


Treatment for SCID