Ch 15 DNA Technology/ Genetic Engineering

Selective Breeding Selective Breeding – humans take advantage of naturally occurring genetic variation to pass wanted traits on to the next generation of organisms. 2 methods: Hybridization – crossing dissimilar individuals to bring together the best of both organisms. Inbreeding – the continued breeding of individuals with similar characteristics.

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.

DNA Extraction Chemical treatments cause cells and nuclei to burst The DNA is inherently sticky, and can be pulled out of the mixture This is called “spooling” DNA

“Spooled” DNA

Cutting DNA Restriction enzymes cut DNA at specific sequences Useful to divide DNA into manageable smaller fragments

Electrophoresis Also known as DNA fingerprinting. Used in forensics – study of crime scene evidence. DNA can be separated based on size and charge The phosphate groups are negatively charged DNA is placed in a gel and electricity is run through

Electrophoresis Negative DNA moves toward the positive end of the gel Smaller fragments move farther and faster through the gel.

Electrophoresis

Steps in DNA Sequencing Many copies of a single strand of DNA are placed in a test tube DNA polymerase is added A mixture of DNA nucleotides is added some of which have dye molecules attached Each base (A,T,C,G) has a different color dye

Steps in DNA Sequencing The enzyme uses the unknown strand of DNA to make a new strand. By chance, some dyed nucleotides & some regular ones are added Dye molecules are large and stop the chain from growing

DNA Sequencing The result is DNA fragments of multiple sizes with colors that can be identified

DNA Sequencing After the gel separates the resulting fragments by size, we 'read' the sequence from bottom to top.

Copying DNA Polymerase Chain Reaction Also called PCR A method of making many copies of a piece of DNA or gene.

Steps in Copying DNA A DNA molecule is placed in a small test tube DNA polymerase that can work at high temps is added

Steps in Copying DNA The DNA is heated to separate the two strands Primers, short pieces of DNA, complementary to the ends of the molecule to be copied, are added Provide the place for the DNA polymerase to start working

Copying DNA The tube is cooled, and DNA polymerase adds new bases to the separated strands

Large amounts of DNA can be made from a small starting sample PCR Large amounts of DNA can be made from a small starting sample

Cloning Clone- a member of a group of genetically identical cells produced from a single cell. A body cell from one organism and an egg cell from another are fused The resulting cell divides like a normal embryo

Cloning “Dolly” 1997

Human Genome Project Started in 1990 Research effort to sequence all of our DNA (46 chromosomes) Over 3.3 billion nucleotides Mapping every gene location (loci) Conducted by scientists around the world

Benefits of Human Genome Project Improvements in medical prevention of disease, gene therapies, diagnosis techniques … Production of useful protein products for use in medicine, agriculture, bioremediation and pharmaceutical industries. Improved bioinformatics – using computers to help in DNA sequencing …

Recombinant DNA Recombinant DNA – joining together DNA from two or more sources. This technique makes it possible to change the genetic composition of living organisms.

Biotechnology and Benefits of Genetic Engineering: The use of gene science to create new products from plants and animals Improved food products Medical advances An enhanced environment

Biotechnology Breakthroughs Insulin (1982) First commercial biotech product Reliable, inexpensive source of insulin Rice Enriched with beta-carotene and iron Bananas Containing edible hepatitis vaccine

Biotechnology Breakthroughs Potatoes with higher solid content Garlic that lowers cholesterol Fruits and vegetables that reduce risks of cancer and heart disease

Environmental Benefits Reduced pesticide use Lower energy requirements Cleaner water Less soil erosion