1. Section 15-1: Selective Breeding

2.  When humans allow only organisms with “wanted” or “desired” characteristics to produce the next generation  Technique used for thousands of years to produce new varieties of cultivated plants and domesticated animals  Two methods: hybridization and inbreeding

3.  Crossing dissimilar individuals to bring together the best characteristics of both organisms  Hybrids often hardier than either parent  Example: crossing a disease resistant plant with one that produces a lot of food

4.  Continued breeding of individuals with similar characteristics  Maintains desirable characteristics in a line of organisms  Example: pure bred dogs and cats  Can be risky – higher chance of recessive alleles pairing, genetic defects

5.  Scientists who manipulate organisms’ genetic makeup are using biotechnology – the application of a technological process, invention, or method to living organisms  Types of biotechnology include selective breeding, increasing mutation rates, using drugs to create polyploid plants, and others

6.  Using radiation or chemicals (mutagens) can increase the rate of mutation  Breeders can create mutants with beneficial characteristics  Example: oil digesting mutant bacterial strains are used to help clean up oil spills; working on bacteria that can clean up radioactive substances or metal pollution

7.  Drugs that prevent chromosome separation in meiosis are useful in plant breeding, to create polyploid plants that are larger and stronger than the normal diploids  Many important crop plants are polyploid

9. College Prep Biology Mr. Martino

10.  Gene Therapy: transfer of one or more modified genes into an individual’s cells  Correct genetic defect  Boost immune system  Recombinant DNA Technology: science of cutting and recombining DNA from different species  Genes are then placed into bacterial, yeast or mammalian cells and replicated  Genetic Engineering: genes are isolated, modified, and inserted back into a cell  also called biotechnology

11.  Restriction enzyme: enzyme that chops up DNA at a specific sequence  Bacterial  Viral defense mechanism  May cut a DNA strand a few times  Helpful in studying DNA  Produces “sticky ends” which may pair with other DNA  Genome: all the DNA in a haploid number of chromosomes for each species

12.  Plasmids: small circle of DNA  In bacterial cells  Insert foreign DNA (gene) into and put back in bacteria – reproduces naturally making a DNA clone  Cloning vector: plasmid used to accept foreign DNA and replicate it  Reverse transcriptase: enzyme from RNA viruses that perform transcription in reverse (RNA to DNA)  cDNA: (copied DNA) mature mRNA transcript that has already been spliced  Bacteria cannot remove introns and splice exons  Reverse transcriptase makes DNA from mRNA to insert into plasmid

13.  PCR: a fast method of amplifying (making lots of copies) DNA  DNA isolated, mixed with DNA polymerase, nucleotides, and some other good stuff  Produces 2 daughters  Daughters replicate, etc.  1 DNA molecule generates 100 billion in a few hours  Used in evolution research, analyze DNA from fossils, analyze embryos, court cases

14.  No two people have exactly identical DNA  Except identical twins  DNA Fingerprint: unique set of DNA fragments  Used to determine paternity, solve crimes, etc.  99.9% all human DNA is identical  Focus on highly variable areas of tandem repeats  Mutations occur within families and are more common in these areas

15.  Gel electrophoresis: uses an electric current to force DNA fragments through a gel  DNA is negative  Size of fragment determines how far it migrates  The fewer tandem repeats the farther it travels  Differences in homologous DNA sequences resulting in fragments of different lengths are restriction fragment length polymorphisms (RFLP’s)

17.  1995 – entire DNA sequence for a bacterium was determined  4/25/03 – Human genome completed  Several bacteria, yeast, Drosophila,C. elegans - worm, Arabidopsis - weed, Mickey…a mouse, just completed 3/31/04 – a rat)  Used a sequencing machine

18.  Genomic Library: set of DNA fragments from an organism’s genome  Complementary RNA sequence can be synthesized with a radioactive isotope tag called a probe  Used to find a specific gene  Tags the gene whenever encountered  Gene may then be isolated

19.  True human insulin is now manufactured  Also somatotropin (growth hormone), blood-clotting factors, hemoglobin, interferons (cancer research), and various other drugs and vaccines  Bacteria for oil spill clean up and other environmental pollution

20.  Genetically engineered plants have been developed for pharmaceuticals, herbicide, pest, and disease resistance, larger and tastier plants, fruits, and vegetables with greater yields  Corn, cotton, potato, soy bean, etc

21.  Cloning holds promises for future  Clone organs and tissues  Possibly modify animals to be more disease resistant and produce greater quantities of products  Not currently occurring in farm animals

25.  1997 – the first animal was cloned – Dolly a lamb  1. Remove nucleus from cell  2. Transfer nuclei from desired cells into unfertilized eggs  3. Implant the “zygote” into surrogate mother  Since Dolly – we have cloned mice, rats, cows, cats, mules, horses, and Rhesus monkeys along with a couple of endangered animals

27.  HGP – an int’l effort to map and sequence all human genes  15 countries started 11/1/90 and finished 4/25/03 (50 years after Watson & Crick paper published)  1. Genome – only 30,000 genes so it took less time  Includes mapping & sequencing of other species for comparison  2. RNA transcription – more difficult since 30,000 genes code for 80,000 proteins due to alternative splicing  3. Proteome – quest for every human protein

28.  HGP already has an ethics committee due to insistence of James Watson  HGP needs to be used to help people and must be regulated by laws  Must prevent invasion of privacy and discrimination by insurance companies, employers,etc.  Must prevent Eugenics: purging of “undesirable” traits from human population (Hitler)  Science provides society with knowledge and opportunities – society requires rules and constraints to prevent abuse

29. Section 15-3: Applications of Genetic Engineering

30.  Genetic engineering used to improve products we get from plants and animals  Could lead to better, less expensive, more nutritious food, and safer manufacturing processes

31.  Genetically modified plants since 1996  Example: adding bacterial genes that produce Bt toxin - kills insects  No pesticides needed  Higher crop yields  Resistance to herbicides, viral infections, rot and spoilage  Some being made to produce plastics

33.  30% of milk produced by cows modified with hormones that increase milk production  Pigs that produce leaner meat, high levels of omega-3  Salmon with extra growth hormone to make them grow quicker  Canada – goats that produce silk  Goat milk with antibacterial enzymes

34.  Scientists hoping to clone transgenic animals to increase food supply and save endangered species  2008 – gov’t allowed sale of meat and milk from cloned animals  Avoid complications of traditional breeding, duplicate exactly

35.  Making more nutritious plants  Producing antibodies to fight disease  Make proteins we need

36.  Transgenic animals used as test subjects  Study defective genes, disease progression  Conduct drug tests

37.  Recombinant DNA technology used to make human proteins to treat disease – human growth hormone, insulin, blood-clotting factor, cancer-fighting proteins  Also gene therapy – the process of changing a gene to treat a medical disease or disorder  Absent or faulty gene replaced with a normal, working gene

39.  Very risky  Need a more reliable way to insert working genes  Make sure it’s not harmful

40.  Hundreds of diseases/disorders can be tested for  Some use labeled DNA probes that can detect disease-causing alleles  Some search for changes in cutting sequences  Some use PCR to detect differences in length between normal and abnormal alleles

41.  Not every gene is active in ever cell all the time  Understand how cells function by studying active genes using DNA microarray technology - measures level of activity of genes

42.  Glass slide or silicon chip to which spots of single-stranded DNA are attached – each spot with a different DNA fragment  Colored tags label source of DNA

44.  Red spots = more cancer mRNA  Green spots = more normal mRNA  Yellow spots = both

45.  No 2 individuals are genetically identical (except identical twins)  Regions of chromosomes contain repeated sequences that do not code for proteins that differ from person to person

46.  DNA fingerprinting analyzes sections of DNA that have little/no function but that vary widely from one individual to another  Use REs to cut DNA into fragments, electrophoresis to separate fragments

47.  DNA probe detects fragments with highly variable regions  If enough probe/enzyme combos are used, resulting banding pattern can be used to distinguish a person  DNA from any tissue can be used

48.  Forensics = study of crime scene evidence  Uses DNA fingerprinting to solve crimes, overturn convictions  Wildlife conservation

49.  When genes are passed parent to child, the markers used in DNA fingerprinting are scrambled  Y chromosome, however, passed directly from father to son with few changes – paternity tests  Pieces of mitochondrial DNA (mtDNA) also passed from mother to child directly – 2 people with the same mtDNA share a common maternal ancestor