1. CHAPTER 21 VIRUSES MONERA
STRUCTURE
AND SHAPE
CLASSIFICATION
REPRODUCTION
RETROVIRUS
ORIGIN OF VIRSUSES
CLASSIFICATION
STRUCTURE
ECOLOGY/
ADAPTATION
REPRODUCTION
ECONOMIC IMPORTANCE
Bacteria Testing

2. 21:1 Structure and Shape of viruses
Don’t possess life functions
Composed of Protein coat and Genetic materials ( DNA or RNA)
Most are spherical or other geometric form

3. Shape of viruses
Many are spherical with projections

4. More Virus shapes

5. Filamentous virus Ebola

6. Complex Virus Structures

7. HIV MODEL
RNA
Inner protein
Core Protein Coat
Enzymes

8. Virus slides
1- Influenza virus
2- Polio virus
3- Tobacco Mosaic virus

9. Virus Sizes
With electron microscopy the level of resolution is 5nm (1nm = 10-9 meters). To put this into some kind of perspective:
an atom is about nm in diameter
DNA is about 2nm in diameter. A small virus
parvovirus has a diameter of about 25nm. A large virus (e.g.
poxviruses) have a diameter of up to 300nm.

10. Classification of Viruses
Grouped by the type of genetic material they have
Single strand of DNA
Double strands of DNA
Single strand of RNA
Double Strands of RNA
Shape and size

11. Virus Families Poxviridae (pox viruses) Parvoviridae Reoviridae
Picornaviridae (Hepatitis A virus, foot-and-mouth disease virus)
Togaviridae (Rubella virus)
Flaviviridae (Hepatitis C virus, yellow fever virus)
Rhabdoviridae
Bunyaviridae (Hantaan virus)
Herpesviridae (Human Herpes Simplex Viruses 1&2, VZV, Human

12. Virus Families continued
Adenoviridae
Papovaviridae (Papillomaviruses)
Hepadnaviridae (Hepatitis B virus)
Caliciviridae
Arenaviridae
* Paramyxoviridae (Measles virus)
* Orthomyxoviridae (Influenza viruses A-C)
* Filoviridae (Ebola virus)
* Retroviridae (HIV-1&2, HTLV-1)
* Astroviridae

13. Viral Reproductions
Since viruses are nonliving they must use a host for reproduction. The host provided all the material and energy to replicate itself.
Viruses are very specific in which types of cell they require as host. This is why it is very difficult (but not impossible)to get a virus infection from an animal.
Two types of reproductive cycles
Lytic cycle
Lysogenic cycle

14. Lytic Cycle Attachments Entry ( injection / endocytosis )
DNA or RNA replication
Assembly New protein coat added
Releasing new virus
Lysis
Budding
Cell membrane channels

15. Replication steps

16. Movie clip showing Replication

17. Lysogenic Cycle see page 508
Attachment
Entry
Provirus formation
Cell Division
Trigger
Lytic cycle

18. Retrovirus The most complex RNA viruses
During injection of their RNA they also inject a special enzyme that help in the reverse transcriptase
See page 510
HIV is such a virus

19. ORIGIN OF VIRUSES
The theory is that viruses originated from cells who DNA or RNA some how escaped a developed a way to reproduce as parasites.
This would indicate that new viruses could be continually being made.

20. Monera (Bacteria)
Archaebacteria - ancient bacteria that live in extreme enviroments.
Oxygen free environments
salt water environments
hot acidic waters

21. Life on Mars

22. Eubacteria- Heterotrophs
Heterotrophs- decomposers
Eubacteria - Chemosynthetic
Eubacteria- Photosynthetic

23. Bacteria structures Shapes coccus- round bacillus- rod shape
spirallus- cork screw shape
Arrangements
diplo-
staphylo-
strepto-

24. Shapes of Bacteria

25. Coccus - Round shape

26. Bacillus- Rod Shape

27. Bacillus 2 E. Coli sem x1815

28. E.coli Sem x49,440

29. Streptomyces sem x 5,510

30. Spirallus bacteria

31. Naming of Bacteria
Names are a combinations of the shape and the cluster arrangements.
Example
diplococcus
streptococcus
staphylbaccillus

32. A typical bacteria structure
Prokaryotes- Lack a membrane bound nucleus.
Cell wall- Different chemical composition than plants- complex polysaccharide (not found in eukaryotes)
Plant cell walls contain cellulose.
See Transparency # 44

33. Structures continued
Capsule- slimy material that covers the cell wall. Protects the bacteria.
EX. Capsule protects the cell from the white blood cells and antibodies produced by animal cells.
Cell membrane- located just inside the cell wall. Prokaryotes lack organelles. All reactions take place in the folds of the cell membrane.

34. Structure continued 2
Cytoplasm- contains ribosome (synthesize proteins). If bacteria carry out photosynthesis chlorophyll is contained here.
Hereditary material (DNA)- Lack a "true" nucleus. DNA is circular. Found in the nucleolid. Plamids are smaller segments of DNA.

35. Structures continued 3
6.Endospores- Formed within the cytoplasm. Contain DNA and a small amount of cytoplasm. Form when conditions are unfavorable. Allows the bacteria to remain dormant. When conditions become favorable the bacteria will grow again. Developed this trait for survival

36. Protection from Osmotic rupture
Like most living things the concentration of water and other liquids is higher outside the organism then inside
Most bacteria have a thick cell wall composed of sugar molecules linked with amino acids.

37. Penicillin- Bacteria Killer?
Penicillin kills bacteria by interfering with the amino acids that link the sugars together in the cell wall
This rupturing of the wall allows water to rush in lysing the cell

38. Ecology and Adaptations
Obligate aerobes bacteria require oxygen
Obligate anaerobes live in an oxygen free environment. - oxygen will kill them.
Endospores are formed by some bacteria when conditions become harmful to them

39. Reproductions
Binary fission- asexual process - bacteria will simply undergo mitosis
Sexual reproduction - Chromosomes are exchanged from one bacteria to another through the Pili

40. Reproduction

41. Rod shape bacteria with Pilus

42. SEM of Pili

43. Economic Importance
Nitrogen fixation - all organism need nitrogen to construct things like protein, DNA, RNA and ATP.
Nitrogen fixation - occurs in some bacteria that are able to get nitrogen from the air (N2) and convert it to NH3 or NO2, NO3

44. Nitrogen Fixing nodules

45. Economic Importance 2
Bacteria cause organic material to decay. This allows for the recycling of nutrients.
Some bacteria use fermentation which makes a variety of molecules with distinctive flavors and aromas- Yogurt, cheese, vinegar.

46. Why to we culture bacteria?
to study them in more detail
to study or improve strains of bacteria.
to identify which bacterium has infected you and therefore what treatment to begin.

47. How Bacteria are cultured?
Life forms require certain foods, water and temperatures to exist bacteria are no exception.
Each type of bacteria prefers either sugars, starch, fats or proteins. So by providing a certain nutrient you will encourage a specific type of bacteria to grow.
Temperature should be 20 C to 37 C

48. Inoculation
Adding bacteria to a culture dish is called inoculation

49. Inoculation results

50. Inoculation results 2

51. Inoculation results 3

52. Culture Results
By Studying pure culture plates of a bacterial species, and observing the texture, aroma, color, growth pattern, height of the growth, and other physical characteristics of the colonies, you can learn a lot about the specimen.

53. Testing Bacteria
One way to determine how to treat a bacteria is to determine the type of cell wall it has.
Thick wall usually indicate a Gram positive type
Thin wall usually indicate a Gram negative type

54. Gram Negative test
It was found that thick wall bacteria will stain differently than those that have thin wall.
The Gram negative test uses a process to stain bacteria.

55. Gram Positive They are usually Coccus and Bacillus in shape
Most are harmless to people and are used for their fermentation process to make foods.
Examples of common Gram-positive cells include Staphylococcus aureusand Streptococcus cremoris, a bacterium used in dairy production.

56. Gram Negative These bacteria are more harmful then helpful
Afflicted individuals are usually treated with streptomycin or erythromycin.