1. Virus & Bacteria Unit

2. Part 1: Viruses
Big Idea: VIRUSES ARE NOT LIVING BECAUSE THEY DON’T FULFILL ALL THE CHARACTERISTICS OF LIVING THINGS.

3. Definition Viruses are tiny particles unlike any other organism.
A virus consists of genetic material such as RNA or DNA wrapped in a protein coat.

4. Characteristics of Life
Homeostasis
Nutrition
Transport
Respiration
Synthesis
Growth
Excretion
Regulation
Reproduction
Is a virus living?

5. Is it living?
No, because a virus can not reproduce on its own. It needs a host cells.

6. How does a virus’ size relate to the size of the cell?
Viruses are much smaller than a cell and that is why they can easily get into a cell

7. How are viruses characterized?
Characterized as:
Plant
Animal
Bacterial virus

8. What are the two parts that comprise a virus?
Nucleic Acid Core (either RNA or DNA)
Protein Coat called a capsid

9. Shapes of Viruses
1. Rod shaped (tobacco mosaic virus)

10. Shapes of Virus
2. Polyhedral (Mumps)

11. Shapes of Virus
3. Helical (Herpes)

12. How does a DNA virus replicate?
DNA virus produces RNA (transcription)
RNA directs production of viral proteins OR
Viral DNA combines with host cell’s DNA

13. How does RNA virus replicate or reproduce itself?
Once inside the host, an RNA virus directs the host cell to produce proteins OR
Viral RNA may make DNA

14. Retrovirus
Virus that has RNA as its genetic material
Example is HIV

15. Bacteriophage Virus that attacks a bacterial cell
Two types of infection:
Lytic Cycle
Lysogenic Cycle

16. Lytic Cycle Bacteriophage attaches to host cell and injects its DNA
Foreign DNA produces more proteins in the host cell
Causes cell to lyse (or break open) and the virus/phage is released into the host’s body

17. Lytic Cycle

18. Lysogenic Cycle Bacteriophage injects DNA into the host cell
Bacteriophage’s DNA integrates itself into a chromosome
Bacteria reproduces

19. Lysogenic Cycle

20. Bacteria Unit Big Idea:
BACTERIA ARE PROKARYOTIC CELLS THAT HAVE DIFFERENT SHAPES, STRUCTURES, & FUNCTIONS IN THEIR ENVIRONMENT.

21. What is a prokaryote?
Cells that lack a true nucleus.
Cells that lack membrane-bound organelles.
Most surrounded by a cell wall.
Many secrete a protective slime capsule.

22. How big is a prokaryotic cell?
1- 5 micrometers
(1 millionth of a meter)

23. Classification
Archaebacteria vs Eubacteria

24. Archaebacteria
Surrounded by a cell wall lacking peptidoglycan.
Live in extreme conditions

25. Examples of Archae
Methanogens: convert H2 and CO2 into methane gas for energy
Halophiles: love salt
Thermoacidophiles: love heat and acid

26. Eubacteria:
Surrounded by a cell wall made of peptidoglycan.
Example: rhizobium nitrogen–fixing bacteria

27. Identifying Prokaryotes
1. Shape:
Coccus – spherical
Bacillus – rod-shaped
Spirillum – spiral
Vibrio – comma shape

28. Bacillus
Coccus
Vibrio
Spirillum

29. Cocci and Bacilli may group together
Prefixes for arrangements:
Diplo – two
Ex. Diplococcus

30. Strepto – chain
Streptococcus
Streptobacillus

31. Staphylo - clustered
Staphylococcus

32. 2. Motility: ability to move
Flagella: whip-like structure used to propel bacteria
Slime: glide along slime secretion
Spiral motion: cork-screw motion (spirillum)

33. 3. Metabolism: Oxygen or NOT
Obligate Aerobes: Need oxygen
Obligate Anaerobes: cannot live in oxygen
Facultative anaerobes: can live with or without oxygen

34. 3.Metabolism: Obtaining Energy
Autotroph vs. Heterotroph
Photoautotroph- uses light energy for photosynthesis
Chemoautotroph- uses energy from inorganic chemicals for chemosynthesis

35. Photoheterotrophs- uses photosynthesis and eats organic compounds
Heterotroph – consumes organic compounds

36. What role do chemosynthetic bacteria have in the ecosystem?
review
What role do chemosynthetic bacteria have in the ecosystem?

37. Bacterial Reproduction

38. Asexual: Binary fission
Circular DNA replicates
Cell membrane and cell wall divide
Identical daughter cells separate

39. How fast does this happen?
approximately every 20 minutes

40. Genetic recombination
Sharing or exchanging of genetic material
3 types:
Conjugation
Transformation
Transduction

41. 1. Conjugation
A temporary bridge forms between two cells.
A plasmid, a separate section of DNA, is transferred from one cell to the other.
Often the plasmid contains useful genes, like antibiotic resistance.

42. 2. Transformation
Bacteria takes in DNA from the environment.
Dead bacteria may break apart and release DNA.
Other bacteria can pick up this DNA and become genetically different.

43. 3. Transduction
Viruses can pick up small amounts of DNA from a host bacteria.
When it infects another bacteria, the new DNA is transferred into that cell.

44. Disease
Pathology is the study of disease.
Pathogens: organisms that cause disease.

45. Exotoxins
Poisonous proteins that are released by some gram-positive bacteria.

46. For example
Clostridium tetani secretes an exotoxin that causes tetanus.
Tetanus causes stiffness in muscles.
Clostridium botulinum produces a very powerful exotoxin that causes the fatal disease, botulism.
1 g of botulism toxin can kill 1 million people.

47. Endotoxins
Lipids and carbohydrates in the cell membranes of some Gram-negative bacteria, that are poisonous.
They are released when the bacteria die.

48. For example:
Most species of Salmonella, are endotoxin producing bacteria.
Salmonella typhi, causes typhoid fever.

49. Antibiotics
Antibiotics interfere with the bacteria’s cellular activities.

50. For example: Penicillin: blocks the building of the cell wall.
“Accidently” discovered by Alexander Fleming in 1920s
Tetracyline: blocks protein synthesis.

51. Where do antibiotics come from?
Antibiotics are naturally made by some fungi and bacteria.
Some are made synthetically in labs.
But most used in treatment still come from bacteria.

52. Antibiotic-Resistance
Bacteria can quickly adapt to their environment because of their rapid rate of reproduction.

53. Antibiotic-Resistance
If one bacterium mutates and becomes resistant,
then in the presence of antibiotics, bacteria not resistant die
Those with the resistance take over the population.

54. Which diseases are preventable by better sanitation practice?
Cholera
Salmonella
Tetanus
Staph

55. What are other ways that antibiotic resistance is passed?
Genetic recombination