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CHAPTER 16 The Origin and Evolution of Microbial Life: Prokaryotes and Protists. 4.8 BYA - earth The early atmosphere probably contained H 2 O, CO, CO 2 , N 2 , and possibly some CH 4 , but little or no O 2 – reducing atmosphere. Figure 16.1A. = 500 million years ago.

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slide2

4.8 BYA - earth

  • The early atmosphere probably contained H2O, CO, CO2, N2, and possibly some CH4, but little or no O2 – reducing atmosphere

Figure 16.1A

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= 500 million years ago

Earliest animals; diverse algae

Earliest multicellular eukaryotes?

Earliest eukaryotes

Accumulation of atmospheric

O2 from photosyntheticcyanobacteria

Billions of years ago

Oldest known prokaryotic fossils

Origin of life?

Figure 16.1C

Formation of Earth

2 domains of prokaryotes
2 Domains of prokaryotes

Domain Archaea

(Kingdom Archaebacteria)

Evolved first

  • “extreme” bacteria
  • Probably gave rise to eukaryotes based on cell structure (chart pp. 323)
domain bacteria
Domain Bacteria
  • More recent bacteria
  • Most of the bacteria we are familiar with
  • Contain helpful & harmful
phyla classification
Phyla classification
  • 9 major groups or phyla (5 in book)
  • P. Proteobacteria
  • P. Chlamydias
  • P. Spirochetes
  • P. Gram +
  • P. Cyanobacteria
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classified by shape & clustering

  • SHAPES
  • Spheres
  • Rods
  • Curves & sprirals
    • Clustering
  • Strepto
  • Staphylo

Figure 16.9A-C

morphology
Morphology
  • Gram positive bacteria
  • Gram negative –
nutrition niche
Nutrition & Niche
  • Heterotrophs (organic C)
  • Autotrophs (CO2 for C)
  • Photo- (use of sun for NRG) or chemo- (use of inorganic compounds for NRG)
how did they ever evolve
How did they ever evolve??
  • mutations
  • Conjugation
  • Transduction
  • Transformation
how do they cause harm
How do they cause harm?
  • Exotoxins
  • Endotoxins
    • Toxins released when bacteria die
  • Enzyme destruction of tissue
    • Attachment of bacteria to cell, enzymes “digest” cell
control of bacteria
Control of Bacteria
  • Prevent entry to body
  • Antibiotics
    • Antibiotic resistance
viruses

Viruses

… a little bit of left-over life…

what is a virus
What is a virus?
  • Non-living
  • Particle
  • Obligate intra-cellular parasites
    • Can only “live” and make more within a host
effects of viruses
Harmful

Virulent

Temperate

Helpful

Transduction

Breeding

TMV and other viruses often destroy chlorophyll – unique coloration

Effects of Viruses
classified by
Classified by…
  • Shape
    • Icosahedral, spherical, rod, lunar-lander
  • Genetic Material
    • DNA – makes mRNA & thus viral proteins OR
    • RNA –
  • Host they infect
    • The living world – plants, animals, bacteria
structure
Structure
  • Protein coat surrounding a core of genetic material =
  • Viroid -
  • Prion -
  • Bacteriophage –
how they work
How they work
  • Must infect host cell - specificity
  • Take over the host’s genetic machinery
  • Vectored by
  • Can cause immediate harm or “wait” for the right time to become “active”
lytic cycle
Lytic Cycle
  • Fast cycle, immediate harm
  • Absorbtion
    • Recognition of host
  • Entry
    • Often only the DNA/RNA
  • Replication
    • Many copies of viral genes made
  • Assembly of new viruses
  • Release to reinfect other cells
    • lyse
lysogenic cycle
Lysogenic Cycle
  • Slow cycle with dormant or latent period
  • Absorbtion
  • Entry
  • Formation of prophage –
  • Replication without harm – host makes many copies of virus as it copies its own genetic info for mitosis
  • Stimulus –
hiv the lysogenic cycle
HIV & the Lysogenic Cycle
  • HIV + vs. AIDS
  • Dormant phase of 8-10 years
  • When activated, so much virus is present, symptoms appear very rapidly
  • Affects T4 cells or the “white blood cell immunity army”
    • NO defence against other “invaders”
control of viruses
Control of Viruses
  • NO
  • Prevent entry to body
    • Prevent insect bites, boil water, heat food, clean, cover mouth, no unprotected sex
  • Stop attachment –
  • Stop entry to cell
  • Stop replication – induced mutations
  • Stop lysing
  • White blood cells and immunity