Genetics of Viruses and Bacteria

1. Genetics of Viruses and Bacteria Ch 19 & 20 Everything you need to know about viruses.

2. Infected? With What?How can you tell? • Start with Symptoms: illness is abrupt and is characterized by fever, headache, joint and muscle aches, sore throat, and weakness, followed by diarrhea, vomiting, and stomach pain. A rash, red eyes, internal and external bleeding from all orifices. • Who is at risk? Persons on the southeast coast of Africa, Congo,Sudan, Zaire, and Uganda • Treatment: No known treatment • Disease: Ebola Hemorragic Fever • Surveillance: CDC SPECIAL PATOGENS UNIT, WHO Ebola Outbreak history

3. How the flu Changes. Infected? With What?How can you tell? • Start with Symptoms: Myalgia, fever, headache, extreme tiredness, dry cough, sore throat, runny or stuffy nose, and muscle aches. • Who is at risk? Everyone • Treatment: Bed Rest and Fluids • Disease: Influenza • Surveillance: CDC and WHO Antigenic Shifts Avian Flu PBS

4. The Bacteriophageor Phage • Viruses that attack bacteria

5. Viruses: Are They Alive?

7. Characteristics of Viruses • Much smaller than a bacterium. • Have 2 essential structural features: Nucleic Acid (DNA or RNA) and Protein Coat called a capsid surrounding it. • Must have a host (host range) in order to propagate itself.

8. Viral Shapes Fig 19.3

9. Grouping VirusesFig 19.1 • Presence of a Capsid and Envelope • Whether they contain RNA or DNA • Shape

12. Virus Reproduction • DNA viruses can immediately produce RNA to construct new viruses or become part of host’s DNA. • RNA viruses must uses reverse transcriptase. Hiv Replication

13. HIV is a retrovirus: uses reverse transcriptase. Provirus: integrated viral DNA

14. Phage Lysogenic Cycle DetailsFig 19.6 • Virus replicates without destoying the host cell. • Prophage: Dormant virus within host (HIV) • Prophage switches to lytic phase. • Temperate viruses are capable of both lytic and lysogenic cylces within a bacterium.

15. The Lysogenic Cycle The Lysogenic Cycle

16. Phage Lytic cycle details. • DNA replication produces more viral DNA • Transcription and translation produce protein coats and glycoprotein spikes

17. The Lytic Cycle

19. Virus Evolution • Plasmids (circular DNA in bacteria and Yeast), or Transposons (mobile DNA segments) may have escaped. • May have originated when fragments of host genes escaped or were expelled from cells or from prions. • Can mutate quickly. • Treated with antivirals • Prevented by vaccines.

20. Other non-life forms Viroids and Prions • Viroids: the smallest particles that are able to replicate. • A short, circular RNA that has no capsid • They disrupt plant cell metabolism

21. Prions: (PREE-ahnz) are misfolded proteins that clump together inside a cell. Normal proteins begin to fold and clump as well. The clumping kills the cell. Fig. 19.11 • Composed of about 250 amino acids and have no associated nucleic acid. • Indestructible. Can’t destroy or deactivate through normal cooking temperatures.

22. Prions cause scrapie in sheep, mad cows disease, and Creutzfeld-Jakob disease in humans Good review Clips Of General Concepts

23. Infected? With What?How can you tell? • Start with Symptoms: Severe abdominal pain, weight loss, stomach ulcers, nausea and vomiting. • Who is at risk? Everyone • Treatment: Antibiotics • Disease: Stomach Ulcers caused by H. Pylori • Surveillance: Both National and International By CDC and WHO How it Works

24. What are bacteria? • Single celled microscopic prokaryotes • Circular DNA condensed into a nuceoid. (no nuclear membrane) • With or without a peptidoglycan in cell wall. • Autotrophs or heterotrophs

25. How are bacteria named? Group Arrangement: Strepto= Chains Staphylo= Clusters Shape:

26. Unicellular Prokaryotes No introns Peptidoglycan cell walls Anaerobes or Aerobes Some are Decomposers or Pathogens Some use conjugation No organelles or nucleus E.Coli (used in genetic engenering to make insulin) Some used to fix nitrogen for the nitrogen cycle Viruses placed here for lack of a place to put them. Domain Bacteria: live in moderate environments. Characteristics: Bacteria on Contact lens Plaque on teeth

27. What is the bacterial cell wall made of? • Peptidoglycan (polypeptides and sugar) • Gram Positive: thick peptidoglycan • Stains Purple • Penicillin puts holes in the peptioglycan • Gram Negative: thin peptidoglygan and lipopolysaccharides coating cell wall. • Stains Red (When she felt negative she saw red) • More antibiotic resistant. • Lipids are toxic to humans Mycobacterium leprae or Leprosy E. Coli

29. Parts of a bacteria. • All have a Cell Wall and Plasma Membrane • Cytoplasm, Pilli, Plasmid • Some have Flagella and Capsules • May make Endospores when dormant for protection. Bacterial Conjugation Don’t Look!

30. Conjugation:primitive sexual method. Bacterial transformation. Discovered by Frederick Griffith 1927. Donating DNA

31. How do bacteria reproduce? • Binary Fission =asexual. • Replicate their DNA in Both directions from a single point of origin= Theta Replication, because it looks like Θ. • Very few mutations. But reproduce often.

32. What is a plasmids and what do they do? • Plasmid: foreign, circular, self-replicating DNA molecule in a bacterium. • Bacterium may have more than one plasmid. • Express genes they carry • Create pilli = F plasmid • Resist antibiotics = R plasmid

33. What is an Operon? • A set of genes found in bacteria and phages that combined with the promoterand operator express those genes. • A gene regulation mechanism. • Jacob and Monod (1940) discovered the first operon in E.coli. They found 2 types: • Lac operon: Inducible operon. Always off • Tryptophan operon: Repressible operon. Always on. • The correct signal will switch the Lac on or the Tryptophan off.

34. Operon Operations Lac Operon Overview • Terms to know: • Promoter: Region of the DNA RNA polymerase binds to • Repressor: binds to operator preventing RNA polymerases attachment. Noncompetitive inhibition. • Operator: Site for repressor attachment at the start of the bacterial operon. The AP Version of the Lac Operon

35. The Lac operon: Inducible • Job of the Lac operon: to utilize lactose turning it into glucose and glactose. • Three enzymes necessary to do this: • B-galactosidase, permease, and transacetylase • RNA polymerase must bind to the promoter to allow the cell to utilize lactose. • Allosteric effector, allolactose, acts as an inducer. Allolactose binds to the repressor causing a conformation of the repressor. It can not longer repress. • If a repressor binds to the operator (noncompetitive inhibition) lactose can not be utilized.

36. Tryptophan Operon: Repressible • Continuously on unless switched off by a corepressor. • rRNA polymerase binds to the promoter and transcribes. • Repressor combines with the corepressor on the tryptophan gene it changes conformation, binds to the operator = RNA polymerase can not bind and transcription is blocked. • Turned of when tryptophan levels are high, negative feedback. Tryptophan Operon

37. What is an Allosteric effector? • Tryptophan: Tryptophan Operon • Lactose: Lac Operon • The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site. AP Bio Tryp