Biotechnology• Application of biological science to solving

practical problems• Method we focus on:

I. Breeding Strategies A. Selective Breeding

- indirect manipulation of DNA- select parents with desirable traits

- create “better” individual- oldest way to improve a species- breed cats, dogs, horses, trees, mice

Ways of Selective Breeding1. Inbreeding

- to maintain traits in a population

- mate parents with similar genomes

- keeps desireable traits, but increases risks for undesirable mutations (illness/disease)

2. Outbreeding (Hybridization)

- Crossing of distantly related organisms

- offspring sterile but hardier (hybrid vigor)

- ex. Mule, hybrid corn

Mule

Broccoflower

B. Other Options

1. Use of Mutagens (Mutagenesis)

- radiations or chemicals to cause mutations

- used in bacteria

2. Induced Polyploidy

- use chemical which causes cells to have extra set of chromosomes

- fruits, flowers, and plants larger

- natural or induced with chemical

- lethal in animals

Genetic Engineering- direct manipulation of DNA- cutting and pasting of genes- design organisms or create transgenic organisms- transgenic organism- organism with foreign DNA or rDNA- recombinant DNA (rDNA)- DNA molecule made of DNA fragments from two different species- vector- agent/vehicle used to transport rDNA or gene of interest into organisms

Genetic Engineering

• 1st – You would need a way to carefully cut the DNA containing the gene away from the genes surrounding it.

• 2nd – You would have to find a way to combine that gene with a piece of DNA from the recipient organism.

• 3rd – You would have to insert the combined DNA into a new organism.

• Finally, it would be useful to have a way to read the sequence of nucleotide bases in the gene in order to analyze the genes that you are manipulating.

• Each of these tools are now available, making it possible to insert a gene from one organism into another.

Restriction Enzymes

• Proteins that can cut genes at specific DNA sequences.

• (More that 75 different kinds of restriction enzymes are known, and each one “recognizes” and cut DNA at a particular sequence)

• Restriction enzymes make it possible to cut DNA into fragments that can be isolated, separated, and analyzed.

• The cut ends made by the restriction enzymes produce matching “sticky ends” on the DNA fragment and the cut plasmids.

DNA Recombination

• In the 2nd step of genetic engineering, DNA fragments are incorporated into part of the recipients cell’s genetic material.

• Bacteria contain small circular DNA molecules known as plasmids.

• These plasmids can be removed from bacterial cells and cut with the same restriction enzymes used to produce the DNA fragments.

• The sticky ends from the DNA fragment and a plasmid can be joined end to end, forming a new plasmid that contains a piece of foreign DNA.

• Combined DNA is known as Recombinant DNA.

• The recombinant DNA is mixed with bacteria. Some bacteria will take up the DNA.

• These bacteria can be isolated and grown into large colonies. (clone)

http://library.thinkquest.org/18258/index2.htm

DNA Sequencing

Gel Electrophoresis

a. Method of seperating DNA fragments according to their size

b. DNA slight (-) charge, will run towards (+) charge

c. Shorter DNA fragments will move farthest

But how is this useful?• 1)  To isolate DNA fragments so that they

can be incorporated into a plasmids or some other vector. 

• 2) To map DNA so that we know the exact order of the nucleic acid base pairs (A, T, C, or G) along a DNA strand.

• 3)  To perform DNA Fingerprinting, which can be used to test organic items, such as hair or blood, and match them with the person that they came from.  This is useful in criminal investigations.

http://www.biology.com/learning/molecular/concept2.html

Prokaryotic Control of Gene Expression

Animation 1

Animation 2

Eukarotic Controls of Gene Expression• Gene expression is the

transcription and translation of genes into proteins

• Eukaryotic controls are elaborate than prokaryotes

• Genes are not controlled in clusters

• Proteins called transcription factors regulate transcription by binding to promoters or RNA polymerase– Turned ON or OFF by

chemical signals in the cell

Cellular Differentiation

STEM CELLS are cells that are undifferentiated and have the potential to differentiate into various types of cells

Homeotic Genes

• “Master switches”; control formation of body parts in specific locations

• Small changes in these genes can result in major morphological changes