Unit 5 Applied Genetics Notes

Always remember…

• Technology involved in genetic engineering is called DNA technology.

• This technology can be used to cure diseases, treat disorders, improve crops, and help make people’s lives better.

Isolating specific genes

• Sometimes scientists want to move a gene from one organism to another. How can they do this?

• Genetic engineers use restriction enzymes that come from bacteria to cut DNA molecules into manageable pieces. These enzymes can recognize specific sequences of DNA and cut at that spot.

• When segments are cut, single chain tails of DNA called sticky tails are created on each segment to allow them to bind to complimentary chains of DNA. This allows new sequences of nucleotides to be created.

• Once a segment of DNA has been isolated, it can be transferred to a carrier chromosome called a cloning vector.

• These chromosomes are normally found in bacteria in a ring shape and are known as plasmids.

• The donor gene is inserted into the plasmid and is then separated from the bacteria. Now you have a gene clone that has an exact copy of the gene taken from the original organism. The new gene can allow an organism to show a new trait (glowing cats) or produce a new substance (bacteria that produce human insulin).

• The combination of DNA from two or more sources is called recombinant DNA.

• A host organism that receives recombinant DNA is called a transgenic organism.

DNA Fingerprinting

• A DNA fingerprint is a pattern of bands made up of specific fragments from an individual’s DNA. Each person’s banding is unique (just like a regular fingerprint) and can used to identify that person.

• The method for preparing a DNA fingerprint is called restriction fragment length polymorphism or RFLP analysis. Fragments of DNA are separated in a process called gel electrophoresis.

• To make a DNA fingerprint, a sample of DNA is placed in wells in the gel and then an electric current is run through the gel. The DNA fragments become negatively charged and migrate toward the positively charged end of the gel.

• Each fragment of DNA moves at a different rate with smaller fragments moving at a faster rate. The DNA fragments are split into single chains and blotted onto filter paper.

• Segments of radioactive DNA called probes bind to the DNA on the paper and form visible bands that show up when exposed to photographic film. The bands can be analyzed by a computer. The accuracy of the DNA fingerprints depends on how unique the prints are.

Human Genome Project

Human Genome Project

• The two goals of the human genome project are to determine the nucleotide sequence of the entire human genome (about 3 billion nucleotide pairs or 100,000 genes) and to map the location of each gene on each chromosome.

• This project began in 1990 and was completed in 2003. In May 2006, Human Genome Project (HGP) researchers announced the completion of the DNA sequence for the last of the 24 human chromosomes. How does this differ from the finished human genome announced by HGP researchers in 2003?

• The DNA sequences announced in 2003 were only rough drafts for each human chromosome. While this draft already has advanced medical research, more detail was needed. The draft genomic sequences can be compared broadly to a cross-country road excavated by a bulldozer that leaves behind many gaps across difficult terrain that will require bridges and other refinements

Gene Therapy

• Treating a genetic disorder by introducing a gene into a cell or by correcting a gene defect in a cell’s genome is called gene therapy.

• Some success in treating cystic fibrosis has been seen using gene therapy. A nasal spray that carries a normal cystic fibrosis gene can be sprayed in the nose and delivered to the lungs where it is absorbed by the nucleus of the cells. The treatment must be repeated periodically because the gene is not inserted into the cell’s chromosomes.

• DNA technology is used to produce medical products that are often safer and less expensive than those produced by conventional means.

• Insulin for diabetics can be produced by genetically engineered bacteria. Human growth hormone can be produced and used to treat dwarfism. Interferons can be used to treat viral infections and some cancers by preventing the replication of viruses.

• Genetically engineered vaccines can produce a harmless version of a deadly virus, allowing our bodies to produce antibodies against a deadly pathogen that causes us to become ill.

Some crops have been genetically engineered to become resistant to herbicides used to kill weeds. Other crops could have new genes introduced to their cells that would cause them to be sweeter or bigger.

• Clones, animals that are produced from a body cell rather than sperm & eggs, could allow us to have herds of critters with specific traits.

Cc, Copycat,world’s firstcloned cat.

Cc’s mom

• We could have copies of our pet Rottweiler, Fluffy, forever! How could that be helpful to us? How could it be dangerous?

• Idaho GemThe world's first cloned mule, was born on May 4. He is an identical genetic copy of his brother, a champion racing mule called Taz, and the first clone to be born in the equine family.Photo: Gerry Thomas, Getty Images

The End!