 Chapter 15 Genetics Engineering

15.1 Selective Breeding  Selective breeding:  Allowing only those animals with wanted characteristics to produce the next generation.  What are some things that are used for selective breeding?

Hybridization  Luther Burbank was one of the first selective breeders. He developed over 800 varieties of plants. He did this by using hybridization. The disease resistance of one plant would combine with the food producing capacity of another. This allowed farmers to produce more food.  Hybridization:  Crossing dissimilar individuals to bring together the best of both organisms.

 Inbreeding:  The continued breeding of individuals with similar characteristics.  Think of dogs and trophy animals.

Increasing Variation  Breeders can increase the genetic variation in a population by introducing mutations, which are the ultimate source of biological diversity.  Biotechnology:  The application of a technological process, invention, or method to living organisms.

 What are some things that can cause mutations which can cause diversity?  Radiation or chemicals.  Breeders can increase the mutation rate by using radiation or chemicals.  Many mutations are harmful, with luck and perseverance scientists can use some mutated organisms.  Best example would be bacteria, scientist are able to modify bacteria, to create bacteria strains.

15.2 Recombinant DNA  In 1987, Douglas Prasher, a biologist at Woods Hole Oceanographic Institute in Massachusetts, wanted to find a specific gene in a jellyfish that codes for a molecule called green fluorescent protein, or GFP.  This natural protein, found in the jellyfish, absorbs energy from light and makes parts of the jellyfish glow.  Prasher thought that GFP from the jellyfish could be linked to a protein when it was being made in a cell, a bit like attaching a light bulb to that molecule.

Finding Genes  GFP – Green Fluorescent Protein Isolated from jellyfish Used to label or ‘mark’ other proteins. The GFP gene is added to other genes Weird, but useful results:

Finding Genes  To find GFP: Restriction fragments separated by gel electrophoresis Find the one fragment that binds tightly to a corresponding molecule of mRNA Southern blotting, named after its inventor, Edwin Southern, used to identify the GFP gene Today, it’s quicker and easier to find genes in databases because the DNA of many organisms has been sequenced

 How do scientists copy the DNA of living organisms?  Polymerase chain reaction (PCR):  The technique used by biologists to make copies of a particular gene.

Polymerase Chain Reaction  Polymerase chain reaction (PCR) allows scientists to make many copies of a gene  1. A piece of DNA is heated, which separates its two strands.

Polymerase Chain Reaction  2. Add a primer so that DNA polymerase knows where to bind and start working

Polymerase Chain Reaction  3. DNA polymerase copies the gene. These copies then serve as templates to make more copies.  4. Several dozen cycles can produce billions of copies

 Most DNA polymerase is denatured at high temperature  Polymerase used in PCR is from bacteria that live in hot springs The DNA Polymerase

Changing DNA  Recombinant DNA:  Joining together DNA from two or more sources.  This can create a change in genetic composition of living organisms.

Combining DNA Fragments  A gene from one organism can be attached to the DNA of another organism.  Restriction enzymes cut DNA at specific sequences, producing “sticky ends,” which are single-stranded overhangs of DNA.

Combining DNA Fragments  If two DNA molecules are cut with the same restriction enzyme, their sticky ends will bond to a DNA fragment that has the complementary base sequence. DNA ligase then joins the two fragments.  The resulting molecules are called recombinant DNA.

 Plasmids:  Small circular DNA molecules.  Joining DNA to a plasmid, and then using the recombinant plasmid to transform bacteria, results in the replication of the newly added DNA along with the rest of the cell’s genome.

 The recombinant plasmid has a genetic marker, such as a gene for antibiotic resistance  Genetic marker:  Joining DNA to a plasmid, and then using the recombinant plasmid to transform bacteria, results in the replication of the newly added DNA along with the rest of the cell’s genome.

Transgenic Organisms  How can genes from one organism be inserted into another organism?  Transgenic organisms can be produced by the insertion of recombinant DNA into the genome of a host organism.  Transgenic:  Organisms that contains genes from another organism.

 The universal nature of the genetic code makes it possible to construct organisms that are transgenic, containing genes from other species.  Like bacterial plasmids, the DNA molecules used for transformation of plant and animal cells contain genetic markers that help scientists identify which cells have been transformed.  By examining the traits of a genetically modified organism, it is possible to learn about the function of the transferred gene.

Transgenic Animals  Scientists can transform animal cells using some of the same techniques used for plant cells.  The egg cells of many animals are large enough that DNA can be injected directly into the nucleus.  Once the DNA is in the nucleus, enzymes that are normally responsible for DNA repair and recombination may help insert the foreign DNA into the chromosomes of the injected cell.

 What was the first animal to be cloned?  Clones of animals were first produced in 1952 using amphibian tadpoles.

 What was the first animal to be cloned that you heard of?  Dolly the sheep  When did this happen?  July 5 th, 1996  Did she die?  February 14 th, 2003

 Clone:  Member of a population of genetically identical cells produced from a single cell.  The technique of cloning uses a single cells from an adult organism to grow an entirely new individual that is genetically identical to the organism from which the cell was taken.

Steps in Cloning  1. The nucleus of an unfertilized egg cell is removed.  2. Next, the egg cell is fused with a donor cell that contains a nucleus, taken from an adult.  3. The resulting diploid egg develops into an embryo, which is then implanted in the uterine wall of a foster mother, where it develops until birth.  4. Cloned cows, pigs, mice, and even cats have since been produced using similar techniques.

15.3 Applications of Genetic Engineering  How can genetic engineering benefit agriculture and industry?  Genetic modification could lead to better, less expensive, and more nutritious food as well as less-harmful manufacturing processes.

GM Crops  Since 1996, GM plants have been an important component of our food supply.  GM crops made up 92% of soybeans, 86% of cotton, and 80% of corn grown in the United States.  GM have Bt toxin, which kills insects, and is harmless to animals and humans.

GM Animals  About 30% of our milk have come from cows that have been injected with hormones.  Use growth hormones to grow salmon more quickly.  In Canada, scientists combined spider genes into the cells of lactating goats, the goats began to manufacture silk along with their milk.

Health and Medicine  How can recombinant-DNA technology improve human health?  Preventing disease  Medical research  Treating disease  Genetic testing

 Gene therapy:  Process of changing a gene to treat a medical disease or disorder.  An absent or faulty gene is replaced by a normal, working gene. Gene therapy allows the body to make the protein or enzyme it needs, which eliminates the cause of the disorder.

Examining Active Genes  DNA microarray:  Studies hundreds or even thousands of genes at once to understand their activity level.  Scientists can study which cells are active or inactive and what their functions are.

 If you commit a crime, what are something's you do not want to leave behind?  DNA, fingerprints…. Etc  DNA fingerprinting:  Analyzes sections of DNA that may have little or no function but that vary widely from one individual to another.

DNA fingerprinting

 Forensics:  The scientific study of crime scene evidence.  DNA evidence has saved more than 110 wrongfully convicted prisoners from death sentences.

Who is this guy? What does he say?