Download Chapter 20 Notes: DNA Technology

NOTES – CH 15 (and 14.3) DNA Technology (“Biotech”)
 BIOTECHNOLOGY: the use of living organisms or their components to do practical tasks
“TRADITIONAL” BIOTECH:
**Practical goal of biotech = improvement of human health and food production
DNA Technologies:
1) Making a recombinant DNA molecule
2) Gene therapy
3) DNA fingerprinting
4) Cloning
Recombinant DNA:
 Combining fragments of DNA
;
 Result: organisms with their DNA + foreign DNA - such organisms are known as:
.
Example of transgenic organism:
– it glows!
 Tobacco plant that contains a
“Toolkit” for DNA technology involves:
-
-
-
RESTRICTION ENZYMES = enzymes that recognize and cut short, specific DNA sequences
 are used to cut out a
from an organism’s genome;
 recognize sequences that are “palindromic” (the same letters backward and forward);
 typically cut sequences in a “staggered” manner so that the two ends of the fragments are single-stranded;
 create “sticky ends” so that the DNA fragment from one organism will be complementary to the DNA fragment
from another organism. (
)
Gene Splicing:
 GENE SPLICING =
foreign DNA is recombined into a bacterial plasmid or viral DNA
VECTORS =
-
after cutting with restriction enzymes –
from test tubes back into cells
(small, circular DNA molecules that replicate within bacterial cells)
HOST ORGANISMS: bacteria are commonly used as hosts in genetic engineering because:
 bacterial cells are simple, and grow quickly,
any foreign genes they carry.
Gene Cloning:
• Once the foreign DNA has been transferred into the host bacterial cell, it replicates every time the cell divides;
• CLONES =
Gene Expression:
• In addition to copying the introduced foreign gene, bacterial cells will also EXPRESS the genes (make the protein
the gene encodes!)
• EXAMPLE: if the gene for human insulin is inserted into a bacterial plasmid and then into a host bacterial cell, that
cell will start to make HUMAN INSULIN!
Steps Involved in Cloning a Human Gene:
1) Isolate human gene to clone;
2) Isolate plasmid from bacterial cell;
3) Add a restriction enzyme to cut out human gene & add same R.E. to open up bacterial plasmid (creates
complementary “sticky ends”);
4) Combine human gene with bacterial plasmid;
5) Insert recombinant DNA plasmid back into bacterial cell;
6) As bacterial cell reproduces, it makes copies of the desired gene…and expresses that gene (makes
whatever protein the gene encodes)!
Applications of DNA Technology:
• Recombinant bacteria in
;
• Recombinant bacteria in
;
• Recombinant bacteria in
;
•
;
•
.
Recombinant bacteria in industry:
• Bacteria that can:

;

;
 extract minerals from ores.
Recombinant bacteria in medicine:
• Bacteria that have received human genes and produce:

;

;
 the amino acid phenylalanine.
Recombinant bacteria in agriculture:
• Bacteria that:

;
 produce natural fertilizers;
 prevent crops from spoiling after harvest.
Transgenic animals:
• Engineer / produce animals with human diseases so that they can be studied in detail.
Transgenic plants:
• Plants that are engineered to:

;
 produce internal
;
 increase protein production.
Other DNA Technologies:
• Polymerase Chain Reaction (PCR);
•
;
• Gel Electrophoresis;
• Gene Therapy;
•
The Polymerase Chain Reaction (PCR)
 allows any piece of DNA to be quickly copied many times in the lab;
 BILLIONS of copies of DNA are produced in just a few hours (enough to use for testing);
 PCR is highly specific; only a small sequence is amplified

.
Starting materials for PCR:
•
•
• Primers
• DNA polymerase
Applications of PCR:
 analyze DNA from tiny amounts of tissue or semen
;
 analyze DNA from single embryonic cells for prenatal diagnosis;
 analyze DNA or viral genes from cells infected with difficult to detect
;
 used extensively in Human Genome Project (14.3)
Analysis of Cloned DNA: GEL ELECTROPHORESIS
 separates DNA molecules based on
 a mixture of DNA fragments will be
, each consisting of DNA molecules
of the same length
Steps Involved in DNA Fingerprinting:
1) Collect DNA from a sample;
2) Perform PCR if necessary to make more DNA;
3) Cut DNA apart using RE’s
4) Electrophoresis is used to separate DNA pieces on a
gel to create a banding pattern;
5) Photo of DNA gel is taken as evidence;
6) Banding patterns can then be compared.
Gene Therapy:
• GENE THERAPY = the
human cells to correct genetic disorders
• Diseases treated include:

 SCID (immune deficiency)
into