Genetic Technology

Section 11.1

What is Biotechnology? Biotechnology is using living organisms to

produce something useful for humans Selective breeding – breeding organisms to

produce desirable traits Inbreeding – crossing of organisms that have

similar genotypes so the desirable traits will eventually be homozygous (crops, horses, dogs . . . not people!) Can also increase the chance of harmful recessive

traits showing up

Consider Dalmatians . . . A white coat with crisp spots is

the desired look breeders want However, the presence of white

in the hair coat increases the likelihood of deafness

Breeders were selecting for the perfect coat color, but at the same time they were also selecting the gene for congenital deafness!

8% of all Dalmatians in the US are bilaterally deaf and 22% are unilaterally deaf

Hybridization Outbreeding – crossing distantly related

organisms Combines desirable traits from different parents Hybrid vigor – larger, healthier offspring may be

produced, but often sterile if different species. Mule from male donkey and female horse is more docile

than donkey but hardier than a horse

Genetic Engineering Genetic engineering – manipulating genes

for practical purposes. Can yield changes in a very short period of

time

Cohen and Boyer (1973) Stanley Cohen and Herbert Boyer

They isolated the gene that codes for rRNA from the DNA of an African clawed frog.

They inserted the gene into E. coli bacteria. During transcription, the bacteria produced

frog rRNA!

Changing Genomes Recombinant DNA – formed when DNA is

combined from different organisms Human genes that produce human proteins can be

added to bacteria or yeast to mass produce the proteins

Mechanism of Recombination, 3D animation with with basic narration

Genetic Engineering to Procuce Insulin

Changing Genomes Vector – carrier of the DNA

Plasmid – small circular pieces of DNA found in bacteria

Genes are spliced into the genome of the vector by utilizing restriction enzymes and sticky ends Restriction Enzymes –

recognize specific DNA sequences and cut the DNA between specific nucleotides

Sticky Ends – pieces of DNA with short single stands on each end that are complimentary to each other

MakingMakingINSULININSULIN

Human Human DNADNA

RestrictiRestriction on enzymes enzymes cut the cut the DNADNA

DNA DNA FragmentFragments with s with “Sticky “Sticky Ends”Ends”

Small, Small, Circular, Circular, Bacterial Bacterial DNA =DNA =PlasmidPlasmid

Restriction Restriction enzyme cuts enzyme cuts the plasmidthe plasmid

Insulin gene Insulin gene inserted into inserted into plasmidplasmid

rDNA used rDNA used as vectoras vector

Eaten Cheddar Cheese Lately?One of the most successful applications of recombinant DNA technology

for foods is the production of chymosin, an enzyme used in cheese making. Chymosin, when added to milk, causes the curd to form.

Chymosin, which was available only from the stomach of calves, was in limited supply due to a reduction in the veal industry and expansion of the cheese industry.

Then the gene for chymosin production was incorporated into the DNA of both bacteria and yeasts. Pure chymosin can now be made. The enzyme is identical to that produced in the calf and the process itself adds no contaminants. The FDA evaluated the safety of the process and the product itself in 1990 and ruled that the enzyme preparation was safe for human consumption.

Most Americans who have had a slice of Cheddar cheese since 1990 have eaten a product improved by biotechnology.