SUBMIT HOMEWORK ASSIGNMENT FROM LAST WEEK

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

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

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

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

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.

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

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

Viruses Lytic vs Lysogenic 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

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.

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.

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)

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.

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

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

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

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

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

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

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 .