chapter 16 the origin and evolution of microbial life: prokaryotes and protists
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
CHAPTER 16The Origin and
Evolution of Microbial Life: Prokaryotes and
Protists
• 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
Figure 16.1C
= 500 million years ago
Earliest animals; diverse algae
Earliest multicellular eukaryotes?
Earliest eukaryotes
Accumulation of atmosphericO2 from photosyntheticcyanobacteria
Oldest known prokaryotic fossils
Origin of life?
Formation of Earth
Bil
lio
ns
of
ye
ars
ag
o
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
– More recent bacteria
– Most of the bacteria we are familiar with
– Contain helpful & harmful
Phyla classification
• 9 major groups or phyla (5 in book)
• P. Proteobacteria
• P. Chlamydias
• P. Spirochetes
• P. Gram +
• P. Cyanobacteria
Importance
SHAPES• Spheres• Rods• Curves & sprirals
classified by shape & clustering
Figure 16.9A-C
Clustering• Strepto
• Staphylo
Bacterial cell morphology
Bacterial Plaque
Morphology• Gram positive bacteria
• Gram negative –
Nutrition & Niche• Heterotrophs (organic C)
–
• Autotrophs (CO2 for C)• Photo- (use of sun for NRG)
or chemo- (use of inorganic compounds for NRG)
Reproduction & Growth
conjugation
How did they ever evolve??• mutations
• Conjugation
• Transduction
• Transformation
How do they cause harm?
• Exotoxins
• Endotoxins– Toxins released when bacteria die
• Enzyme destruction of tissue– Attachment of bacteria to cell, enzymes
“digest” cell
suvivorship
Common bacterial Diseases
transmission
Control of Bacteria
• Prevent entry to body
• Antibiotics– Antibiotic resistance
Viruses
… a little bit of left-over life…
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
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
• Protein coat surrounding a core of genetic material =
• Viroid -
• Prion -
• Bacteriophage –
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 • 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• 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 + 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
• 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