Biotechnology

Guess the lamb’s name

DOLLY!--THIS IS A PHOTO OF THE FAMOUS CLONED SHEEP

Goals of Applied Genetics1. Help humans create crops that can be frost resistant2. Use transgenic organisms to help medical

researchers model human physiology for testing3. Help industry to create bacteria to break down

pollutants into harmless products4. Pharmaceutical companies use recombinant DNA to

cheaply produce human hormones (insulin) and other proteins

5. Help solve crimes and determine familial relationships

Selective breeding• Selecting organisms with the most desirable

traits• Requires time and several generations to

produce offspring with the desired trait

• Ex:– Short vs long haired cats– Milk production in cattle– Disease resistant foods– Bacteria that break down oil

Genetic Engineering• Also called, recombinant DNA

technology or gene cloning

• Uses a bacterial host because of fast reproduction and a circular DNA vehicle to hold the foreign DNA=plasmid

Organisms containing recombinant DNA or foreign DNA are known as transgenic

Steps involved:1. select the desired gene(s) to be inserted

into the organism and a bacterial host containing a plasmid (vehicle to hold the desired gene)

2. cut specific DNA molecules into fragments with special (restriction) enzymes

3. splice (rejoin) the fragments (gene and plasmid) together in the desired combination

4. introduce or insert the new DNA into a living cell for replication (mitosis)

= Vector to transfer DNA

Restriction Enzymes

• Used to cut a DNA molecule at a specific nucleotide sequence

• Produces one of two types of DNA fragments

1. Sticky ends (palindrome)

2. Blunt ends

Sticky Ends (palindrome)

Blunt ends

= Vector to transfer DNA

Vectors• Vector: in nature, an organism that can

transmit DNA to another organism, often an infection

• Biotechnology uses this ability to transfer desired genetic information to a host cell.

Gene Libraries

• Store DNA sequences for biotech applications

• May use plasmid or phage • (Phage: virus that infects bacteria and looks like a

spaceship)

• May contain entire genome or only DNA used in gene expression.

• Expressed DNA is called cDNA (complementary DNA) and is made from mRNA with the enzyme...

Reverse Transcriptase!!!!

Gene Cloning• Used to produce genetically identical copies

of a cell, tissue, organ, and/or organism• Needed to produce multiple copies of the

desired DNA

Cloning Applications

Currently • Plants are cloned to produce a large

number of genetically identical plants in a short amount of time

Future?2. Clone productive and healthy animals

to increase yield for farmers and to grow organs for transplants

How it works….

Gene Therapy• The insertion of normal genes into human

cells to correct genetic disorders like cystic fibrosis.

DNA Fingerprinting1. Obtain a small sample of DNA2. Make millions of copies using PCR

(polymerase chain reaction) technique3. Cleave (cut) DNA with restriction

enzymes4. Separate DNA fragments using gel

electrophoresis and compare 5. Each human’s DNA will have some

unique pieces because each of our DNA is unique

Restriction Fragment Length Polymorphism (RFLP)

• RFLP: Each individual.....has different numbers of restriction sites...different # of base pairs between restriction sites

• Gel electrophoresis is used to create a DNA fingerprint of these unique sizes.

• Small amounts of DNA are loaded into wells in the gel.

• An electric current pushes the small pieces of DNA farther down the gel than the larger pieces.

RFLP• DNA patterns are compared to known patterns.• Used for forensics, blood samples, and paternity

tests (children get half their bands from mom and half from dad)

Running a gel…

How DNA moves…

Step 1: Pour gel with comb for wells,not unlike a jellomold.

Step 2: Pipette DNA into wells.

DNA has been cut with restriction enzymes.

Step 3: Run an electric current to watch DNA migrate.

Small strands, fewer base pairs, travel further.

Step 4: Notice similaritiesand differences in banding patterns.

The Human Genome Project

• There are approximately 80,000 genes on the 46 human chromosomes

• Human Genome Project- an international effort to completely map and sequence human chromosomes (April 2003)

Southern Blotting• Purpose: to use a cloned gene to probe for

the same gene in another sample.

• Named for Edward M. Southern-– Western and Northern Blots play on that

name– These have slightly different procedure

(Western involves protein rather than DNA)

Southern Blotting• Unknown DNA is run on a gel.• DNA bands are blotted onto special paper.• Paper is flooded with labeled complementary

DNA

p32

Southern Blotting• Hybridization: Single stranded DNA probe

binds to any complementary DNA on paper, and the rest is washed off

• Bands that are hybridized are radioactive and can be visualized.

• http://www.accessexcellence.org/RC/VL/GG/ecb/southern_blotting.html

Uses of Radioactive Probes

• Biochemists use radioactive probes to find things such as:– Genes– Proteins

• Enzymes• Receptors on membranes• Antigens (by using radioactive antibodies)

Bioinformatics

• This area of study uses genetic material (or any biological material) to gather information.

Such as…

Bioinformatics

• Whether a gene is similar to a previously sequenced gene.

• Whether a specific gene is correlated with a specific disease, such as which genes are prevalent in cancer cells.

• Whether a certain drug can benefit or harm a patient based on the patient’s genotype.

Credits

• This Power Point was provided by Abby Price and modified by Andrea Wise, Providence High School, 2007