1. Prokaryotes and Viruses
Biology I

2. 16.1 Prokaryotic life began on a young Earth
Stromatolites= Ancient fossils found in dome-shaped rocks
Used as evidence bacteria were present 3.5 billion years ago.

3. How did life begin? Origin of small molecules
1953 Stanley Miller, simulated conditions on early Earth
Formation of Organic Polymers
How did polymers form?
Heat and clay help bind organic monomers together
Lightening was energy source

4. Formation Cont. What was the original process of inheritance?
RNA, short strands could replicate without the use of enzymes
Formation of Pre-Cells
Early organic materials and RNA became encased in membranes

5. Supports 4 stage process:
First, small organic molecules, such as amino acids and nucleotides
Second, these small molecules joined together into larger ones such as proteins and nucleic acids.
Third, molecules that could copy themselves provided a basis for the inheritance of molecular information.
In the last stage, these various organic molecules became packaged within membranes and separated from their surroundings. In other words, they formed pre-cells.

6. Where did life begin? Shallow waters and moist sediments such as clay
Deep-sea thermal vents

7. 16.2 Diverse prokaryotes populate the biosphere
Diversity of Prokaryotic Life
-found EVERYWHERE

8. Archaea “ancient” bacteria Extremophiles: Consists of three types
Thermophiles – heat lovers
Halophiles – salt lovers
Methogens – live anaerobic environment, produce methane gas
DNA evidence indicates closer relationship to eukaryotes than bacteria

9. Differences between Archaea and Bacteria
Differences in RNA and DNA information
Enzymes that catalyze RNA are different
Bacteria lack introns
Antibiotics effective only to Bacteria
Archea cell walls lack petidoglycan

10. Structure and Function of Bacteria
Bacteria is identified and distinguished based partly on three characteristics.
Cell Shape
–cocci (round)
bacilli(rod)
spiral(spirochetes)

11. Structure and Function of Bacteria
Cell Wall Structure
Two types of cell walls
Determined by a Gram stain
Gram positive bacterium (purple)
Gram negative bacterium (pink)

12. Structure and Function of Bacteria
Motility
Flagella
Pili
Slimy threads

13. Asexual Reproduction Binary fission Rapid reproduction
Cloning of the parent
Can have mutations, antibiotic resistance

14. Sexual Reproduction
Transformation – bacterium takes up free DNA from the environment
Conjugation – two bacterial cells temporarily join and directly transfer genetic material between them
Transduction – virus phage inserts genetic material
Endospore Formation – dormant bacteria with highly resistant outer wall

15. Genetic Variation

16. Modes of Nutrition

17. Cyanobacteria and Oxygen
Believe to be the first photoautotrophs.
Helped bring oxygen in the atmosphere
Revolutionized the evolution of aerobic organisms and cellular respiration.

18. 16.3 Prokaryotes perform essential functions in the biosphere
Chemical recycling– help in breaking down or decomposing, organic waste products and dead organisms
e.g. carbon locked in organic compounds returned to atmosphere as CO2
Used in nitrogen gas conversion through legumes

19. Nitrogen Cycle

20. Human uses of bacteria
Use of organisms to remove pollutants from water, air and soil – bioremediation
Used in sewage treatment, oil clean up, mining clean up, genetic exploration
PCB clean up

21. 16.4 Some Prokaryotes cause disease
Pathogen – bacteria or other microorganism that cause a disease.
Bacteria can invade the cell and destroy it
Develop toxins
Secrete toxins from the bacterial cell Exotoxins
can destroy the cell or interfere with cell function
Cause digestive problems or paralysis
Toxin is a component of the bacterial cell wall Endotoxins
Causes the body to respond (immune system) with fever, aches, weakness, or can lead to shock.

22. Diseases and Methods of Transmission
Inhalation
Anthrax
Tuberculosis
Sexual
Syphilis
Gonorrhea
Bites
Lyme disease
Improperly stored or prepared foods
Botulism
salmonella

23. Bacterial Diseases Tuberculosis Invades tissues and destroys cell
Engulfs white blood cells

24. Bacterial Diseases caused by poisons
Closstridium botulinum –botulism
1 gram of pure toxin could kill 1 million people
Staphylococcus aureus –Staph infection
Secretes a poison by the bacterial cells
Proteins secreted cause the illness

25. Diseases caused by bacteria
Salmonella –
Is a component of the cell wall that causes the illness
Can also cause typhoid fever

26. Defense against bacteria
Hygiene –wash your hands, stay clean
Clean drinking water
Don’t get run down, weakens the immune system
Antibiotics, resistance to antibiotics

27. 16.5 Viruses infect cells by inserting genes
Virus is not a cell, cannot reproduce on its own.
Structure of a virus
Protein coat
Genetic material, either RNA or DNA

28. Virus reproduction Two reproductive cycles Lytic cycle
1. Host cell produce virus parts
2. Virus parts assemble
3. Host cell bursts, releasing hundreds of complete, functioning viruses
Lysogenic cycle
1. Viral DNA combines with host DNA
2. Host cell replicates as normal
3. Then converts to lytic cycle

29. Viral reproduction

30. Viruses and Disease
Viruses have an outer envelop that help the virus enter and leave a cell
Contain RNA as genetic material
Common cold, flu, measles, mumps, polio, AIDS
Contain DNA as genetic material
Hepatitis, herpes infections
Antibiotic do not work against viruses

31. HIV– A retrovirus
Retrovirus – uses RNA as genetic material versus DNA

32. Defense against Viruses
Vaccines –dead or disabled pieces of virus that fool immune system, form future resistance
First vaccine –Edward Jenner, small pox vaccine
Some may not work as the virus mutate too quickly for a vaccine to work (HIV)