Genetic Engineering Chapter 15 in Textbook

Selective Breeding Selective Breeding: allowing only those organisms with desired characteristics to reproduce. –How could you use selective breeding to develop dogs with more intelligence? –Selective breeding takes advantage of natural genetic variation (the trait must already exist in the population)

2 Methods of selective breeding 1.Hybridization: crossing dissimilar individuals together to get the best of both organisms Ex: Killer Bees – While attempting to create a bee that produces more honey in tropical climates scientist bred a European honey bee with a African honey bee. 2.Inbreeding: the continued breeding of individuals with similar characteristic Ex: Purebred Dog Breeds – dog breeds are created by breeding individuals with similar characteristics to ensure that the combination of traits will be passed on to the next generation. Selective Breeding

In order for selective breeding to work, you need a wide variation of genetic traits. –Explain you cannot use selective breeding to create a monkey that glows in the dark? How do new traits get introduced into a population? –Induce mutations to develop new traits in a population (Mutations are the ultimate source of genetic traits)

Limitations of selective breeding and mutations: –Selective breeding requires traits already exists in a population – we can not make new traits. –Mutations are unpredictable and will not create the exact traits that we want. (most mutations are harmful to the organism) Scientists are learning how to directly manipulate the DNA of an organisms to produce desired traits. Genetic Engineering: the development and application procedures, and technologies that allow you to directly manipulate an organisms DNA Selective Breeding

Gel Electrophoresis: Method for separation and analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on their size and charge Gel Electrophoresis

Basic Steps for DNA Gel Electrophoresis 1.Mix a sample of DNA with a restriction enzyme. Restriction Enzymes: a protein that cuts DNA at a specific nucleotide sequence. Different samples of DNA produce fragments of different sizes. Gel Electrophoresis

2. Separating the DNA fragments –A mixture of DNA fragments is put into one end of a porous gel –An electric current drives the DNA through the gel –The smaller the segment, the faster it moves.

3. Analyzing the Results –Measure the distance the segment of DNA traveled away from the original position. –Smaller fragments of DNA move further across the gel. –DNA always have a negative charge, so it moves towards the positive electrode. Gel Electrophoresis

Recombinant DNA: Molecule of DNA that is created by joining segments of DNA from different sources. How to create recombinant DNA: 1.Cut both 2 different samples of DNA with the same restriction enzyme. –Sticky Ends: Single stranded DNA sequence created after the DNA is cut by certain restriction enzymes Recombinant DNA

2.Join the 2 cut DNA segments together. –Since both of the DNA molecules were cut with the same restriction enzymes the sticky ends will contain complimentary bases. –DNA ligase can be used to fuse together the DNA fragments. –Beside recombinant DNA, in what other process is DNA ligase used? Recombinant DNA

How is recombinant DNA useful? Recombinant DNA can be inserted into bacterial cells to create human growth hormone. How to make bacteria with recombinant DNA: 1.Remove a plasmid for a bacteria cell. –Plasmid: A small, circular DNA molecule in bacterial cells that is separate from the bacteria’s chromosome. Recombinant DNA

2.Cut the plasmid and the human DNA with the same restriction enzyme. 3.Use ligase to join the fragment of human DNA containing the insulin gene with the cut bacterial plasmid. 4.Insert the plasmid with recombinant DNA into a bacteria cell. Recombinant DNA

5.The bacteria cell divides and produces more transgenic bacterial cells that will produce human insulin that can be given to diabetes patients. Transgenic Organisms: Organisms that have had genes from other species inserted into their genome Recombinant DNA

Clone: genetically identical individuals produced from a single cell. Cloned colonies of bacteria and plants are easy to grow How to clone a mammal: 1.Remove the nucleus from a diploid cell of the animal you wish to clone. Cloning The cloned lamb is identical to which sheep?

2.Remove the haploid nucleus of an unfertilized egg cell and replace it with the diploid nucleus. 3.The diploid egg cell will begin to divide, growing into an embryo. 4.The embryo is implanted into a foster mother where it develops until birth. Cloning The cloned lamb identical to which sheep?

Understand the pro and cons of each of the following: 1.Genetically Modified Foods (GMO’s) 2.Designer Babies 3.Cloning Mammals Ethics and Impacts of Genetic Engineering