Genetic Engineering

Agricultural Biology

Introduction

• For thousands of years people have changed the characteristics of plants and animals.– Through selective breeding

– Through exploitation of mutations

• Since breeders have been able to take advantage of naturally occurring mutations they have dreamed of being able to artificially create mutations.

• The ability to design new varieties of plants and animals has now become a reality through genetic engineering

• Genetic engineering involves the manipulation of genes within a cell or organism to bring about a change in the genetic makeup of an organism

• There are several methods of gene manipulation currently used, most of which include the removal and insertion of genetic material into organisms

Gene Mapping

• One of the most important processes in gene manipulation is that of finding the location of genes on the chromosomes

• Gene mapping involves the finding of the particular location on the strand of DNA that contains the genes that control certain traits

• The arrangement of nitrogen bases (A,T,C,G) on the molecule of DNA determine the genetic code

• The process of mapping the genes on the strands of DNA involves the use of molecules that act as probes

– The probes attach themselves to certain parts of DNA where the nitrogen bases join each other

– The probe looks for combinations of where the nitrogen bases join in certain sequences

– Once the probe locates the nucleotides, the sequences of Adenine, Thymine, Cytosine, and Guanine can be listed in a map

• Although coding is extremely complex, the code is the same in all organisms

– The nucleotides only pair with certain other nucleotides.

– The pairing of nucleotides is the phenomena that makes genetic engineering possible

Gene Splicing

• Once the location of the DNA sequence has been located, scientists can use restriction enzyme to separate the DNA at a particular location on the gene

• Once the pieces of DNA are removed other DNA can be spliced in or recombined with the remaining DNA– This results in recombinant DNA

– This new form of DNA will reproduce with the new characteristics of the introduced DNA

The first genetic splicing was done using bacteria– Bacteria has plasmids(circular shaped pieces of

DNA) that float freely in the cell’s fluid

– By selecting the proper enzyme, scientists cut out part of the plasmid DNA and insert DNA from another organism.

– The DNA replicates and the new bacteria produced from the spliced DNA holds the desired characteristics.

• One of the first uses of gene splicing was the manufacture of human insulin

– Scientists isolated the DNA sequence that regulates the production of insulin

– The DNA segment is spliced into the DNA of the E.coli bacteria

– The bacteria carrying the DNA for insulin production reproduces and passes the capability along to the next generation

• The bacteria are produced in large quantities through a process called fermentation

• When the proper number of bacteria are reproduced, they are removed from the fermentation tanks and are taken apart to retrieve the insulin produced.

• The insulin is then separated, purified, and the remains of the bacteria are destroyed

• This procedure provides a ready relatively inexpensive supply of insulin for those people who need it

Other Uses• Bacteria have become the manufacturing centers

for many substances that have made the lives of humans better and more productive

– Vaccines

– Hormones

Bovine somatotrpin (BST)• A relatively recent agricultural innovation using

genetic engineering • A hormone composed of protein that is

produced by the animal’s pituitary gland• Helps control the production of milk by assisting

the regulation of nutrients into the production of milk or fat

• Supplementary BST causes the cow to produce less fat and more milk

• By splicing genetic material into E. coli bacteria the hormone can be produced at a relatively low cost.

Tissue Culture

• Tissue culture- the process of regenerating plants from a single cell

• Through the introduction of new DNA into a single cell, a completely new plant of different genetic makeup can be grown.

Future Uses?????

Societal Concerns

• Even though many feel we must have genetic engineering to produce sufficient food, there is still widespread concern about ethical issues

• Those who develop genetic material believe they should have ownership

• Other believe you cannot own genetic materials, especially human materials.

Societal Concerns

• In 1986 Congress passed the Animal Patent Act allowing patents to be held for genetically engineered animals

• Plants are similarly covered through the Plant Variety Protection ACT

• Since these were passed over 200 patents for GMO’s have been filed for.

Societal Concerns

• Concern is raised about releasing GMO’s into the environment

• Worry that GMO’S will push out native species is a concern

• Greatest fear is that once organisms are released into the environment, there will be no way to remove them.

Regulation of Genetic Engineering

• Labs were research is done are very controlled and secure

• USDA has strict guidelines for developing GMO’s

• Much of the fear people have of GMO’s is misunderstanding