AP Biology Reminders…  Test is Monday/Tuesday  Closed note, group (my choice)  Covers Chapters  Review Guide will be available Thursday.  Quiz Corrections – I’ll take re-writes. Best you can get for the re-take is 85.  Take your time, follow the prompts.

AP Biology Viruses Big Questions: What is a virus? How does a virus function?

AP Biology What a virus is…  “Obligate Intracellular Parasite”  Cannot carry out life cycle independent of a cell host  Composed of:  Genome: DNA or RNA  Protein coat: Capsid  Host can be: any cell (prokaryote or eukaryote)

AP Biology How big is a virus?

AP Biology Prokaryotic Viruses  PHAGES! (bacteriophages)  2 kinds: Virulent phages: Lytic life cycle Temperate phages: Lysogenic life cycle

AP Biology Eukaryotic Viruses  More diverse than phages  DNA or RNA genomes  Double or single stranded  Can have lipid envelope around protein coat  RNA viruses (retroviruses) mutations are very common, so permanent immunity not possible

AP Biology Eukaryotic Viral Replication

AP Biology HIV Life Cycle RNA viruses violate the Central Dogma! Code an enzyme for Reverse Transcriptase HIV destroys immune system cells (T- Helper) which leaves the body prone to opportunistic infections. Drugs try to stop viral replication inside cell. Ex: Protease inhibitors Cost = $1200 month

AP Biology Remember Protein Modifications?  Because HIV is so compact and efficient, it packs many of its protein strings into one long, nonfunctional string.  In order to work, these protein strings need to be cut into different components. When the strings are cut up, they can carry out their specific functions for replication.  Protease Inhibitors prevent this modification and limit the viral replication.

AP Biology Plant Viruses  Plants get viruses too!  Look like “blotchy” pigment patterns

AP Biology What viruses are not…  Viruses are not the most simple kinds of infections:  Viroids: Disease causing RNA molecules in plants  Prions: Disease causing protein molecules Prions  Mad Cow, CJD in humans, scrapie (sheep)

AP Biology Questions – Ask Away!

AP Biology Questions to answer! (Chapter 19) 1. Explain how different types of viruses utilize the information system of cells to complete their life cycles. 2. Compare bacteriophages and eukaryotic viruses. 3. Compare lytic and lysogenic cycles of viral reproduction. 4. Explain the structure and function of HIV. 5. How do viral processes increase genetic variation in organisms? 6. Compare viruses to other infectious particles.

AP Biology Biotechnology

AP Biology Biotechnology today  Genetic Engineering  Electrophoresis  Recombinant Technology  Polymerase Chain Reaction  Transgenics/GMO’s  Cloning

AP Biology Recombinant Technology  rDNA is DNA with 2 or more sources  Bacteria are used to copy DNA and make desired proteins  Identify gene of interest and cut it out  insert new gene into a plasmid  insert plasmid into bacteria  Vector – plasmid carrying new gene into host  bacteria can express new gene or make copies of inserted DNA

AP Biology

Restriction Enzymes – Cut the DNA!  a.k.a.restriction endonucleases  evolved in bacteria to cut up foreign DNA from viruses  Molecular scissors that cut between specific bases  “Sticky Ends” are where the enzyme cut allow for joining with another piece of DNA cut with the same enzyme

AP Biology Recombinant tech.  Transformation  insert recombinant plasmid into bacteria  grow recombinant bacteria in agar cultures  bacteria make lots of copies of plasmid  “cloning” the plasmid  production of many copies of inserted gene  production of “new” protein  transformed phenotype DNA  RNA  protein  trait

AP Biology Recombinant Plasmid  Plasmids used to insert new genes into bacteria gene we want cut DNA cut plasmid DNA insert “gene we want” into plasmid... “glue” together ligase like what? …insulin …HGH …lactase Cut DNA? DNA scissors? recombinant plasmid

AP Biology Grow bacteria…make more grow bacteria harvest (purify) protein transformed bacteria plasmid gene from other organism + recombinant plasmid vector

AP Biology Transgenics – organisms with foreign DNA  Genetically modified organisms (GMO)  enabling plants to produce new proteins  Protect crops from insects: BT corn  corn produces a bacterial toxin that kills corn borer (caterpillar pest of corn)  Extend growing season: fishberries  strawberries with an anti-freezing gene from flounder  Improve quality of food: golden rice  rice producing vitamin A improves nutritional value

AP Biology Green with envy?? Jelly fish “GFP” Transformed vertebrates

AP Biology Many uses of restriction enzymes…  Now that we can cut DNA with restriction enzymes…  we can cut up DNA from different people… or different organisms… and compare it  why?  forensics  medical diagnostics  paternity  evolutionary relationships  and more…

AP Biology Comparing cut up DNA  How do we compare DNA fragments?  separate fragments by size  How do we separate DNA fragments?  run it through a gelatin  agarose  made from algae  gel electrophoresis DNA jello?? Can’t we just add those little marshmallows?

AP Biology  DNA moves in an electrical field…  DNA is negatively charged  size of DNA fragment affects how far it travels  small pieces travel farther  large pieces travel slower & lag behind Gel electrophoresis + – DNA        “swimming through Jello”

AP Biology Gel Electrophoresis longer fragments shorter fragments power source completed gel gel DNA & restriction enzyme wells - +

AP Biology Uses: Evolutionary relationships  Comparing DNA samples from different organisms to measure evolutionary relationships – + DNA  turtlesnakeratsquirrelfruitfly

AP Biology Uses: Medical diagnostic  Comparing normal allele to disease allele chromosome with disease-causing allele 2 chromosome with normal allele 1 – + allele 1 allele 2 DNA  Example: test for Huntington’s disease

AP Biology Uses: Forensics  Comparing DNA sample from crime scene with suspects & victim – + S1 DNA  S2S3V suspects crime scene sample

AP Biology Electrophoresis use in forensics  Evidence from murder trial  Do you think the suspect is guilty? “standard” blood sample 3 from crime scene “standard” blood sample 1 from crime scene blood sample 2 from crime scene blood sample from victim 2 blood sample from victim 1 blood sample from suspect OJ Simpson N Brown R Goldman

AP Biology Uses: Paternity  Who’s the father? + DNA  childMomF1F2 –

AP Biology Copy DNA without plasmids? PCR!  Polymerase Chain Reaction  method for making many, many copies of a specific segment of DNA  ~only need 1 cell of DNA to start It’s a DNA copy machine!

AP Biology PCR process  What do you need to do?  in tube: DNA, DNA polymerase enzyme, primer, nucleotides  denature DNA: heat (90°C) DNA to separate strands  anneal DNA: cool to hybridize with primers & build DNA (extension) What does 90°C do to our DNA polymerase? play DNAi movie

AP Biology Clone  A genetically identical organism or a group of cells derived from a single cell

AP Biology Cloning Process  The nucleus from a somatic (body) cell is harvested  An egg is harvested and the nucleus of the egg is removed  The nucleus from the somatic cell is then transferred into the egg  An electric shock causes the cell to replicate  The embryo is now implanted into the uterus to grow into a new individual

AP Biology Big Ideas of Biotechnology  Genes from virtually any organism can be cloned using plasmid transformation or using PCR.  Electrophoresis and restriction enzymes are widely used in DNA analysis.  GMO’s and cloned animals and plants can be given beneficial characteristics or make needed products such as pharmaceuticals.

AP Biology Now you try… Try: Science Tools/Virtual Labs Also check out: Epigenetics Molecules of Inheritance Cloning Genetic Variation