Genetic+Technologies

= Section 1 Applied Genetics =

Selective Breeding
[|Teosinte's few fruitcases modified to modern corn's rows of exposed kernels through selective breeding]

Inbreeding develops pure lines Inbreeding is mating between closely related individuals. It results in offspring that are homozygous for most traits. Inbreeding can bring out harmful recessive traits because two individuals may carry harmful recessive traits for two alleles. A breed is a selected group of organisms within a species that has been bred for particular characteristics, like a German Sheppard.



Hybrids are usually bigger and better

[|Zebra Hybrid link]

Determining Genotypes


Test crosses can determine genotypes



= Section 2 Recombinant DNA Technology =

Genetic Engineering
Transgenic organisms contain recombinant DNA Transgenic Organisms-  You can take Recombinant DNA, and put it in a host, this host will start copying that DNA and creating more of it as if it were its own. This is a three step process. Plants and animals that retain recombinant DNA are called **transgenic organisms**.  An example of this is the glowing tobacco plant. Biochemists took genes from a firefly and put them in the tobacco plant, to create The Glowing Tobacco plant.

Restriction enzymes cleave DNA To isolate DNA pieces are cut off from chromosomes. Restriction enzymes are bacterial proteins that have the ability to cut both the strands of the DNA molecule at a specific nucleotide sequence. There are hundreds of these restriction enzymes, and each can cut the DNA at a specific point, and the resulting DNA fragments are all different lengths. Some are cut straight across both strands, and are called blunt ends. EcoRI cut palindromic sequences of DNA by unzipping them for a few nucleotides. Fragments that join with other fragments are called sticky ends.



**Vectors Transfer DNA** Vectors are the ways that DNA is transferred into new chromosomes. DNA is added to make changes in the DNA and as such, make changes in the organism. Because of natural equilibrium, various changes stabilize naturally. RNAi follows the same basic principles, causing various RNA functions to stop or start in separate positions, made to create separate proteins. Vectors are either biological or mechanical, depending on their base. Because of the natural affinity of a virus to inject separate DNA into other cells, viruses can have separate DNA implanted to inject into the cells. Plasmids are separate biological vectors used to modify DNA, especially in a bacterium. Mechanical vectors are separate, man-made injectors. A micropipette, a very small syringe, is injected into the cells, which works in much the same way as the virus concept. A DNA ‘gun’ fires a protein/DNA coated bullet into the cell, where the enzymes break down the bullet and absorb the DNA.

Insertion into a vector If a plasmid and foreign DNA have been cleaved with the same restriction enzyme, the ends of each will join together. They will reconnect the plasmid ring. The foreign DNA is recombined into a plasmid (or viral DNA) with help of a second enzyme.

Gene cloning Once foreign DNA has been inserted into the plasmid, the recombined DNA is transferred into a bacterial cell. This plasmid can replicate separately from a bacterial host and can produce up to 500 copies per bacterial cell. The nice thing about using these bacterial cells to clone DNA is that they can reproduce very quickly. So millions of bacteria are produced and they contain lots of recombinant DNA molecules. Each of these identical recombinant DNA molecules are called a gene clone. Plasmids can be used to deliver genes to animal or plant cells too. Every time a host cell divides, it copies the recombinant DNA. The host cell is able to produce proteins that are encoded on the recombinant DNA. Today, scientists are able to produce mutant forms of a protein and determine how that mutation alters the protein’s function within a cell. By using a vector, recombinant DNA can be inserted into yeast, plant, and animal cells.



Cloning of animals Many scientists have tried to create clones over the years. The most famous of all these clones was Dolly the sheep, cloned in 1997. Other various mammals have also been cloned since then, and the process of cloning is becoming more perfect. Huge benefits could come from the practice of cloning animals efficiently. //Dolly the sheep clone, stuffed and in a museum. Yeah!//

Polymerase chain reaction

Sequencing DNA can allow scientists to identify mutations. In DNA sequencing, millions of double-stranded DNA fragments are cloned using PCR. Next, the strands are separated. The single strand fragments are put into test tubes, one for each DNA base. One nucleotide in each tube is tagged with a different fluorescent color. The reactions produce complimentary strands of different lengths. The strands are separated by size by gel electrophoresis. This produces bands in the gel. These bands are seen by using a laser scanner or a UV light. How does gel electrophoresis work? Read the section on it to find out!

Applications of DNA Technology (3rd Period)
Recombinant DNA in industry The production of cheese, laundry detergents, pulp and paper production, and sewage treatment have all been enhanced by recombinant DNA techniques that increase enzyme activity, stability, and specificity. There is research going on to develop high protein corn with protein levels comparable to beef, and making fuel from discarded cornstalks.

Gel electrophoresis

Scientists add restriction enzymes to the DNA. Then, the enzymes break the DNA into several small fragments. A tray of gel is used, and there are small wells that the DNA fragments are placed in. A power source is used to make an electric field having one end of the gel being positive and the other negative. Since the gel is fairly dense only the smaller fragments move faster, yet, all move. DNA is negatively charged so they will move to the positive side.

When scientists manipulate and recombine DNA in different ways, they can use it for help in the medicinal field. Pharmaceutical companies are using recombinant DNA to treat human diseases such as pituitary dwarfism. They use recombinant bacteria, which produce large amounts of insulin, a hormone/protein, to help treat people. Recombinant DNA provides safe vaccines for diseases which there are no prevention.
 * __ Recombinant DNA in medicine __**

Transgenic animals A transgenic animal is an animal that has DNA from different sources. Mice are good test subjects for transgenic testing because they reproduce quickly, their chromosomes are similar to human chromosomes, and scientists know the location of many genes on mouse chromosomes. The roundworm and the fruit fly are often commonly used. In a farm in Scotland, a transgenic sheep was produced with the corrected human gene for hemophilia A. The farm has also created sheep which produce a protein that assists lung functions. These proteins can be used as medicines.

//Recombinant DNA in agriculture//

Recombinant DNA and biotechnology have been used to increase the efficiency of plant growth by increasing the efficiency of the plant's ability to fix nitrogen. [|Nitrogen fixation] is the utilization of the free gaseous nitrogen in the air by soil bacteria – either in cooperation with the plants (legumes) or without plants – to produce useable nitrogen products which plants and other organisms can use (just as plants would use commercial fertilizers) to grow and produce protein, fiber, and seed. For clarity; the term "useable" nitrogen can be substituted for "fixed" nitrogen. Scientists have obtained the genes for nitrogen fixation from bacteria and have incorporated those genes into plant cells. The plant cells can then perform a process that normally takes place only in bacteria.

CliffsNotes.com. //DNA and Agriculture//. 26 Mar 2009 .



= Section 3 The Human Genome =

Mapping and Sequencing the Human Genome
Linkage maps

Sequencing the human genome The first step in sequencing the human genome is to break the DNA into samples using restriction enzymes. After that each piece is cloned and sequenced. After that the cloned fragments are aligned in proper order by overlapping the matching sequences. Then they take the fragments, putting them together to see the longer sequence. Automated machines often do this work and are beginning to make the job very fast.

Applications of the Human Genome Project
Diagnosis of genetic disorders

Gene therapy- People who have genetic disorders can now try an experimental technology called GENE THERAPY. GENE THERAPY is the insertion of normal genes into human cells to correct genetic disorders. So far over 3000 patients have tried to use gene therapy. They have tried to treat SCID (severe combined immonodeficiency syndrome). The tests on these have been the most successful. This disorder is where the affect person's immune system shuts down, so all sicknesses are threatening. To treat this they take out bone marrow and put good marrow in. They also have done gene therapy in cystic fibrosis, sickle-cell anemia, hemophilia, and other disorders.

= Comprehension Check = = What effects are a result of inbreeding for offspring? = =What is one thing that can determine genotypes? What is the most famous clone? What are DNA fragments which join with other DNA fragments called?=

DNA fingerprinting