SUBMIT HOMEWORK ASSIGNMENT FROM LAST WEEK

1. SUBMIT HOMEWORK ASSIGNMENT FROM LAST WEEK

2. 2.1 The Organization of Life/ Viruses2.2 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 • LyticvsLysogenic Cycle • http://www.youtube.com/watch?v=NUrGNd-a76E • 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. Archaeavs 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. Archaeavs Bacteria • NO Archaea perform photosynthesis • Aerobic respiration (requires oxygen) • Photosynthetic BACTERIA exist however (cyanobacteria) 6CO2 + 6H2O → C6H12O6 + 6O2 • Both are prokaryotes, so why are they in two different domains? • Obtain energy differently

17. Archaeavs Bacteria • 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 • Both are prokaryotes, so why are they in two different domains? • Obtain energy differently

18. Archaeavs Bacteria • 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 • Both are prokaryotes, so why are they in two different domains?

19. Archaeavs 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 .