1. Microbiology
Microbiology is the field of biology that studies microorganisms such as:
viruses • archaea • eubacteria • protists • fungi
Microorganisms are either:
prokaryotic – cells which have no mucleus and no membrane-bound organelles (archaea and eubacteria, the two types of bacteria)
eukaryotic – cells which have numerous membrane-bound organelles including a nucleus (protists, fungi, plants, animals)
Microorganisms usually require magnification to be observed. Many are unicellular (made of a single cell) and others form multicellular groups of associated cells.

2. Most microorganisms can go through two types of reproduction:
asexual
sexual
asexual reproduction (one cell reproduces itself)
production of offspring from a single parent
an exact copy of a cell and its DNA is made (e.g. mitosis, binary fission, cloning)
the genetic information (DNA) of the offspring is identical to the parent
sexual repoduction
production of offspring from the union of two sex cells, one from each parent (ex. Meiosis – humans produce eggs and sperm)
the genetic information (DNA) of the offspring is different from the parents

3. 6 Kingdom Classification System
1. Archaebacteria / 2. Eubacteria 3. 4. 5. 6.

4. The 5 Kingdoms
Archaebacteria / Eubacteria

5. Viruses
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SBI3U - A.Y. Jackson S.S. 5 5

6. Viruses
Questions
Where do viruses fit into the model of the 6 Kingdom classification system?
Are viruses considered living organisms? 6 6

7. Viruses What are the characteristics of living organisms?
Living things…
are made of cells
grow and develop
reproduce
respond to their environment
adapt to their environment
obtain and use energy
produce wastes 7 7

8. Viruses More realistic size of a virus compared to an animal cell
Magnified image of a virus
Image of an animal cell
cells can fulfill all characteristics of life
viruses on their own can be considered lifeless chemicals, unless ……? 8 8

9. Viruses Answer … unless they are reproducing
viruses are not considered to be living organisms because:
not made up of cells
only capable of 1 life function
i.e. reproduction & only within a living cell
outside cells, viruses are lifeless chemicals 9 9

10. Typical Viral Stucture
capsid:
protein coat for protection
core:
either DNA or RNA (genetic material)
Receptor sites:
spikes that help virus attach to its
specific host cell 10 10

11. Typical Viral Stucture11 11

12. Viral Capsids
Viruses come in many shapes.
Examples:

13. Viral Classification (DNA or RNA) Viruses are generally classified by:
1. the organisms they infect
host range (types of cells that the virus can infect)
examples: a) cold virus
b) rabies
c) HIV
d) bacteriophage
2. structure
size and shape of the capsid
type genetic material
(human respiratory cells)
(nerve cells in dogs, rodents, humans)
(human WBC)
(bacteria)
(DNA or RNA)
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14. Viral Size very small, measured in units called nanometres (nm)
1nm = 1X10-9 m
(billionth of a metre)
size ranges from nm
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15. Homework
Questions page 107 # 1, 2, 5 – 8
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