1. Biology 102
Biotechnology

2. 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)

3. 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

4. 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)

5. 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

6. How does DNA Recombination occur in nature?
Sexual reproduction
Bacterial recombination
Transfer by viruses

7. Recombination in Bacteria
Bacterium
Plasmid transferred to new host
(b)
(c)
DNA fragments transferred to new host
Chromosome
Plasmid
(a) In addition to their large circular chromosome, bacteria commonly possess small rings of DNA called plasmids, which often carry additional useful genes. Bacterial transformation occurs when living bacteria take up (b) these plasmids or (c) fragments of chromosomes.
Plasmid replicates in cytoplasm
1 µm
DNA fragment incorporated into chromosome
Plasmids allow bacteria to grow in novel environments

8. Transfer of genes by viruses
A virus infecting a eukaryotic cell uses its own genetic material and the host’s cellular machinery to copy the virus. When copies are released from the cell, they can infect new host cells. Segments of the host DNA may be incorporated into the viral genome and transferred to hosts of other species.

9. Genetic engineering in the lab
Create a “DNA” library
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

10. 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

11. 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

12. 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

13. Gel electrophoresis

14. DNA fingerprinting

15. 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

16. 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

17. 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