Control & Manipulation of Genes

 Before Transcription  Access Acetylation loosens grip of histone, allowing access of polymerase to DNA Methylation of an allele blocks that gene’s affect  How transcribed Gene sequences rearranged or multiplied, generate large amounts of gene product

 Transcription Processing  mRNA cannot pass out of nucleus without transport protein  Some proteins can block translation from starting  Translation Control  Affect ribosome components (no rRNA, no translation)  Control speed of breaking down mRNA (how many times it can be reused)

 X Chromosome Inactivation  Females XX  One X chromosome is 75% “shut down”  Barr body—condensed X chromosome  Random

 Operon—arrangement of promoter and operators that control access to a gene  Lac operon in E. coli cells  E. coli normally doesn’t use lactose (milk sugar)  Lac operon binds to gene that would allow use of lactose, prevents it’s transcription  When glucose is scarce but lactose present, activator is synthesized  Activator then prevents lac operon from functioning, allowing lactose to be used  Inhibition can be reversed

 Recombinant DNA—any DNA molecule consisting of base sequences from two or more organisms of the same or different species.  Able to combine genetic sequence of different species  Restriction enzymes  Plasmids & cloning vectors

 A restriction enzyme is added to a solution with DNA  Enzyme “cuts” DNA at a specific place  Can fuse with DNA molecule “cut” with same enzyme

 Bacteria have two forms of DNA  One chromosome, a single circular DNA strand  Plasmids—small circles of “extra” DNA with only a few genes  Bacteria divide rapidly, providing many new organisms in a short period of time.

 In nature, bacteria can share characteristics through plasmids  Antibiotic resistance

 With restriction enzymes, can splice DNA into plasmid  Plasmid taken into bacteria cells

 “Donor” gene is used by bacteria, produces product of gene  Is now part of bacteria’s genetic code, is passed on during division

 Uses  Laboratory studies of specific genes  Produce products quickly & cheaply Insluin Antibiotics  Vaccines Animal diseases HIV Ebola

 Polymerase Chain Reaction (PCR)—method to reproduce fragments of DNA millions or billions of time  Primer—short stretch of synthetic, single- stranded DNA

 Primers are added to solution with DNA fragments and polymerase  Solution is heated, denaturing and “opening” DNA  Solution is cooled  Primers attach to matching base pairs during cooling  Polymerase starts at primer, synthesizes DNA chain  Process is repeated

 Each “cycle” results in exponential growth  Quickly grow a segment of DNA

 Uses  Forensics  Diagnostics (viral & bacterial diseases)  Paternity or relationship testing  Historical analysis Mummies, mammoths, etc.

 DNA is mixed with certain compounds in a solution  The solution is placed into a gelatinous substance  Electrical charge is carried along the gel  The DNA separates along the gel in a pattern based on the structure and weight of the individual genes

 Everyone’s DNA is unique to them  Base-pair patterns different between people  PCR & electrophoresis to find & analyze DNA  1 in 3,000,000,000,000 chance of unrelated people having identical DNA

 1988—National Institutes of Health combined previously begun research into one project  2003—Human genome officially completed  Almost 20,000 confirmed genes  Over 2,000 possible genes  Don’t know what all of these genes do!  Much of human genome DOESN’T code for proteins  Many might regulate expression of other genes…. “Master Control” genes

 Study diseases & disorders  Be able to predict and detect disease  Gene therapy—transfer one or more normal or modified genes into a person’s body cells  Correct genetic defect  Boost resistance to disease  Imperfect at this time

 Bacteria  Insulin  Blood-clotting factors  Hemoglobin  Vaccines  Environmental clean-up Oil spills Pollutants Radioactive waste

 Plants  Drought resistance  Disease resistance  Herbicide resistance  Soil tolerance  Greater yield  Better nutrition

 Animals  Medical research Mice susceptible to human diseases  Disease resistance  Environmental resistance Featherless chickens  Medical proteins Cattle—human collagen (cartilage, bone, skin repair)  Better nutrition Low-fat pigs