GENETIC ENGINEERING BIOTECHNOLOGY We have been manipulating DNA

GENETIC ENGINEERING BIOTECHNOLOGY

We have been manipulating DNA for generations! • Selective breeding – Allowing only those animals/plants with desired characteristics to produce the next generation (foods, vaccines, bidegeneration, antibiotics, vitamins)

Animal Breeding

Breeding Food Plants � “Descendants” of the wild mustard �the “Cabbage family”

Corn from tiosinte plants

Using mutations to increase genetic diversity Selective breeding/artificial breeding would not be possible if it were not for the large amounts of diversity � Biologists/geneticists can increase this diversity by causing mutations in a DNA sequence � �Ex: using this technique scientists have developed several different kinds of helpful bacteria ○ Bacteria that can digest oil and were once used to clean up oil spills

How Can We Do This? � We manipulate the DNA! �Genetic engineering-making changes in the DNA code of a living organism

Can an animal gene be put into a plant or vice versa? � YESSSS!!!! � Steven Howell and his associates isolated the gene that allows fireflies to glow (luciferase), and inserted it into tobacco cells. When these cells were grown into a plant, the entire plant glew in the dark.

Transgenic Organisms � Bacteria �Used most often because of how quickly they reproduce �Genes are spliced in the bacterial DNA; bacteria produce proteins that are coded for in gene; cheap and in great abundance ○ Ex: Insulin �People with insulin-dependent diabetes are now treated with pure human insulin produced by human genes that were inserted into bacteria

Gene splicing

Transgenic Animals � Genes from humans have been inserted into mice to improve their immune systems so that we can use them to test the effects of diseases on the human immune system � Growth hormone is added to have animals grow faster, produce leaner meat � Blood clotting factor mass produced in pigs

Mice from the same litter

Transgenic plants In 2000, 52 percent of soy bean and 25 percent of corn grown in the U. S. was transgenic or genetically modified � GMO (Genetically modified organisms) � Contain genes that produce natural insecticides so that they don’t have to sprayed � Some contain genes that prevent them from being killed by weed killers � Some strawberries and other fruits contain anti-freezing agent found in arctic flounder �

What’s next? � Plants may soon be used to produce human antibodies that can be used to fight disease � Foods that may be resistant from rot � Chicken that is immune to the bacteria that cause food poisoning � Exists already-rice containing Vitamin A which our body produces, increases health of millions around the world

What about humans? � Is it ethical to genetically modify humans? � Should we be able to alter a human’s DNA? � Should there be boundaries drawn?

What already exists? � The Human Genome Project �Contains over 6 billion basepairs �That is 6, 000, 000 A, T, G, and C’s �E. Coli (a bacteria) contains 4, 639, 221 bps � In 2000 a working copy of the human genome was essentially complete �Allows us to look at the human DNA sequence and determine where specific genes are located

Genetic Testing � Genetic testing is now used for: � Carrier screening, or the identification of unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to manifest; � Confirmational diagnosis of symptomatic individuals; � Determining sex; � Forensic/identity testing; � Newborn screening; � Prenatal diagnostic screening; � Presymptomatic testing for estimating the risk of developing adult-onset cancers; � Presymptomatic testing for predicting adult-onset disorders. � Some genetic tests are already available, although most of them are used in developed countries. The tests currently available can detect mutations associated with rare genetic disorders like cystic fibrosis, sickle cell anemia, and Huntington’s disease.

Gene Therapy � Because of the Human Genome Project, we may soon be able to �Cure genetic disorders by gene therapy �An absent or faulty gene is replaced by a normal, working gene �This way, the body can make the correct protein or enzyme it needs, which eliminates the disorder.

Cloning Dolly the sheep was cloned in 1997.

� Clone-member of a population of genetically identical cells produced from a single cell Researchers hope that cloning will enable them to make copies of transgenic animals and even help save endangered species. -Many suffer from genetic defects and health problems.

Cloning in Fruits � Grafting-tissues of one plant are inserted into those of another in order to get desired characteristics � Example: Apples � Some apples cannot be grown from seeds. So they use grafting as a way to clone those apple types

How’s cloning work? Cloned cows, pigs, sheep, dogs, and mice have been produced.

Stem Cells � Cells that have the ability to form any type of cell, which could therefore, be used to grow any type of cell that is needed.

What do you think? � Is the use of stem cells ok? � How should they be limited, if used at all? � What are the potential benefits and dangers?

Biotechnology � What can be done with DNA? �Polymerase Chain Reaction (PCR) �Testing for Specific Alleles �DNA Fingerprinting

Things to think about? � Who controls your DNA? �Use by the U. S. Department of Defense? �Employers using it to discriminate against people carrying certain genes? � Do Genetically Modified foods need stricter controls? �Pg 330

How do forensic scientists figure out who committed a crime from a single drop of blood or a single hair? � Polymerase Chain Reactions �Makes mass copies of a specific gene �DNA is heated to different temperatures in order to break strands apart, primers are added, and DNA polymerase is added to make copies �DNA polymerase came from bacteria in the hot springs in Yellowstone National Park

PCR

DNA Fingerprinting � Helps identify individuals � Does not focus on cell’s most important genes because they are all so similar in every human � Instead focuses on sections of DNA that have little or no known function but vary widely from person to person

� Restriction enzymes-enzyme that cuts DNA at a specific sequence of nucleotides � 1) DNA is collected and run through PCR to increase sample of DNA � 2) Restriction enzymes are added that locate specific sequences in the human DNA and cut DNA into fragments of various lengths

� 3) These different size samples are loaded into an agarose gel where they bands are separated using an electrical current. � 4) A buffer is placed in the electrophoresis chamber before the DNA is run to provide a stable p. H and help conduct the electrical current. � Agarose gel-a pourous gel used to separate different strands of DNA

� DNA has a negative charge!!!

� When the DNA is placed in the gel and the gel in run, which direction will the DNA travel? � The smaller bands of DNA will travel the farthest down the gel, because they can easily travel through the agarose. � The gel is stained and the DNA fragments are compared.