1. SUBMIT HOMEWORK ASSIGNMENT FROM LAST WEEK

2. 2. 1 The Organization of Life/ Viruses 2
2.1 The Organization of Life/ Viruses 2.2 Comparing Bacteria to Archaea

3. Review What are the two types of cell division?
Mitosis and Meiosis
What is the difference between the two?
Mitosis produces 2 identical cells to the parent cell
Meiosis produces reproductive cells—half the number of chromosomes as the parent cells
Why is meiosis important? (Hint: creates one of the 3 types of bio-)
Creates genetic diversity

4. Prokaryotes vs Eukaryotes (Table 2.1)
Two basic cell types recognized by biologists
Eukaryotes
Membrane bound organelles
Unicellular/ Multicellular
Most are aerobic
Reproduce by mitosis/meiosis

5. Prokaryotes vs Eukaryotes (Table 2.1)
Two basic cell types recognized by biologists
Prokaryotes
Circular DNA
No membrane bound organelles
Unicellular
Many are anaerobic
Don’t reproduce by mitosis/meiosis

6. Viruses Neither prokaryotic nor eukaryotic
Not capable of living independently outside of cells—use host cell’s machinery for survival and reproduction
Dormant outside of the living cells
No cytoplasm, membrane bound organelles or cell membranes—not living organisms?
So how are they able to cause disease in plants and animals?
Biologists have a system of classifying viruses, but it is not part of the classification system of life.

7. Viruses WHAT DO VIRUSES LOOK LIKE?
Capsid: the outer protein layer that surrounds the genetic material of the virus
Genetic material can be in the form of DNA or RNA

8. Viruses How do they reproduce? THEY DON’T! They replicate 
Require a host cell (either prokaryotic or eukaryotic)

9. Viruses Lytic vs Lysogenic Cycle
Lysogeny involves viral DNA integrating with host DNA
Viral DNA is then referred to as the provirus.
Lysis refers to the rupturing of the cell membrane.
Lytic Cycle is a part of the Lysogenic Cycle, but not necessarily the other way around.
LYTIC CYCLE: new viruses are made, kills host cell
LYSOGENIC CYCLE: viral DNA is copied during cell division

10. Viruses
In viruses that undergo the lysogenic cycle, effects on the host may not be immediate.
HERPES SIMPLEX VIRUS (cold sores)
Appear when the viral cycle destroys cells
Disappears when the virus is in its provirus stage
The trigger to switch between one replication strategy to another depends on the health of the host cell.

11. Viruses HIV (human immunodeficiency virus)
Only when the infection spreads to more and more cells do the symptoms of AIDS (acquired immune deficiency syndrome) eventually appear
AIDS results in an inability of the body to fight off infection because HIV has destroyed the body’s T-cells (white blood cells)
Death occurs from an accumulation of other infections and ailments, not from AIDS itself.

12. Prions Non-viral disease causing agents
Cause several deadly brain diseases
Like viruses, cause diseases that are not usually detected for decades after infection
Only known disease-causing agents that do not contain DNA/ RNA (and therefore are not viruses)

13. Prions
They are proteins normally found in the body that are converted into a more harmful form (isomer)
Mad Cow Disease is an example of a prion-caused deadly brain disease.

14. Viruses and Biotechnology
Viruses can be useful tools for genetic engineers who want to make a copy of a certain gene
Used for their ability to enter host cells and direct the activity of the host cell’s DNA
Insert the gene into the viral DNA/RNA
Virus enters host cell and directs the cell to make multiple copies of the virus
Each new virus made contains the added gene that researches want copied

15. Archaea vs Bacteria
Both are prokaryotes, so why are they in two different domains?
The two groups are more different from each other than any two groups within the domain
Example?
Archaea have an independent evolutionary history than Bacteria; the two have many differences in their biochemistry
Archaea is actually more closely related to Eukaryotes than Bacteria

16. Archaea vs Bacteria
Both are prokaryotes, so why are they in two different domains?
Obtain energy differently
NO Archaea perform photosynthesis
Aerobic respiration (requires oxygen)
Photosynthetic BACTERIA exist however (cyanobacteria)
6CO2 + 6H2O → C6H12O6 + 6O2

17. Archaea vs Bacteria
Both are prokaryotes, so why are they in two different domains?
Obtain energy differently
Some Archaea: methanogenesis
Form of anaerobic respiration; a process that occurs in environments that lack oxygen
One of the final stages of decomposition
Without methanogenesis, carbon products would accumulate.
CO2 + 4 H2 → CH4 + 2H2O
CH3COOH → CH4 + CO2

18. Archaea vs Bacteria
Both are prokaryotes, so why are they in two different domains?
Live in different habitats
Archaea are extremophiles
They are able to live in environments of extreme heat (Thermophile), acidity (Acidophile), or salt concentrations (Halophile)
Most Bacteria are mesophiles
Habitats of moderate condition; less extreme

19. Archaea vs Bacteria
However they both have similar reproduction strategies
Binary Fission (pg. 62)
In environmentally favourable conditions
Conjugation (of plasmids)
In less favourable conditions
Only bacteria form endospores

20. Homework
Pg. 55 #3, 5
Pg. 58 #4, 6, 14
Pg. 62 #7, 8, 11, 12
Pg. 66 #5, 8
Create a chart comparing Viruses, Bacteria and Archaea .