DNA Technology

Biotechnology Biotechnology is using other organisms to make a specific product Selective breeding chooses plants or animals with certain traits and then allows them to breed

Test Crosses Test crossing is used to determine the genotype of a dominant phenotype Example: You want to make all purple-flowered plants. You don’t know if your parent plant is homo- or heterozygous. How do you find out?

Test Crosses You must cross your purple plant with a white plant. Why? White is recessive, so it has a known genotype (pp). There are two possible outcomes:

Test Crosses Genotypes all Pp Phenotypes all purple Outcome a. PP x pp

Test Crosses Outcome b. Pp x pp Genotypes ½ Pp, ½ pp Phenotypes ½ purple, ½ white P p Pp pp What does is mean if you get recessive offspring?

Applications of DNA Technology Genetic Engineering is the moving of genes from one organism to those of another http://www.fluorescentpets.com/prod31.jpg

Applications of DNA Tech. Industry examples Bacteria are used to: break down pollutants produce cheese, detergent, paper products extract minerals from ores make chemicals like indigo and phenylalanine

Applications of DNA Tech. Medical examples Bacteria are used to produce hormones, proteins, and vaccines Human diseases can be studied in other animals (like mice) http://www.ingenious.org.uk/media/4.0_SAC/webimages/1032/1/10321271_3.jpg

Applications of DNA Tech. Agriculture examples Plants are resistant to frost, pesticides, insects (Bt crops) Plants are made with more vitamins in them (golden rice) Plants can be made non- allergenic

Restriction Enzymes Restriction Enzymes are one of the tools used in genetic engineering The enzymes cleave or digest (cut) DNA into smaller pieces The enzymes look for specific locations in the DNA sequence

Restriction Enzymes Most of the recognition sequences are palindromes The enzyme will cut at a specific point within the sequence

Restriction Enzymes Many times a staggered cut is made This produces “sticky ends” that can readily combine with other cut pieces of DNA

Bacterial Transformation Recombinant DNA is formed by combining DNA from two different sources

Making Recombinant Plasmids Isolate the gene of interest (ex. human insulin) Isolate bacterial plasmid (a small circular piece of DNA) Cut both types of DNA with the SAME restriction enzyme You will get matching sticky ends

Mix the two types of DNA together (gene splicing) Add the enzyme DNA ligase to permanently bond the pieces Insert the plasmid into a host bacterial cell

Getting the recombinant plasmid into a host cell is not easy. Gene gun can “shoot” the DNA into the cell (works best with plants) Injection of DNA Inducing the cells by electric or temperature shocking

Let the host cell replicate many times This produces clones  This is how to make a transgenic organism

Plant Plasmids

Human Genome Project

Human Genome Project The HGP was an international effort to completely sequence and map the human genome genome = all of an organism’s genetic material

Human Genome Project The human genome has between 30,000 and 40,000 genes.

Human Genome Chromosome Linkage Maps show the locations of genes on chromosomes  this is just chromosome #1

Applications of HGP Genetic testing to diagnose genetic disorders Developing gene therapy When normal genes are inserted into cells to correct genetic disorders

Gene Therapy This technique() has been used to treat SCID, sickle-cell anemia, hemophilia Cystic fibrosis has been treated with cold viruses

Applications of HGP DNA Fingerprinting This is the unique banding pattern created when a sample of DNA is cut and separated Restriction enzymes cut the DNA Gel electrophoresis separates the cut pieces by size

Gel Electrophoresis Cut DNA is loaded into a slab of gel (wells are usually at one end) Electrodes are attached to opposite ends of the gel

Gel Electrophoresis, cont. Negatively charged DNA is pulled towards the positive pole Small pieces move easily through the gel, thus travelling farther

Gel Electrophoresis

Uses of DNA Fingerprints Paternity testing (Who’s the Daddy?) Forensic analysis to identify suspects and unidentified victims Classify new organisms/fossils

Polymerase Chain Reaction What if you only have one drop of blood left at a crime scene? How do you test that? Scientists can make billions of copies of DNA by PCR (polymerase chain reaction) This simulates DNA replication, but only takes a few hours