Evolution of Microbial Life: Prokaryotes and Protista

1
Evolution of Microbial Life Prokaryotes and
Protista

• Prokaryotes
• Bacteria
• Archaea
• Protists

2
Prokaryotes have inhabited earth for billions of
years

• Fossil record shows prokaryotes abundant 3.5 bya
• Currently, collective biological mass is at least
  10 times that of eukaryotes
• There are tens of thousands of species (many of
  which have not been described)

3
Prokaryotes come in a variety of shapes

• Coccus spherical
• Streptococcus, staphloylococcus
• Bacillus rods
• Spirillum curly Q

4
Prokaryote External Structures

• Gram
• Simple walls with thick peptidoglycan
• Gram
• Complex walls with little peptidoglycan, outer
  membrane

5
Prokaryote External Structures

• Capsule
• Sticky layer of polysaccharides

• Fimbriae
• Hairlike appendages, help anchor bacteria
• Motility
• Many have flagella (lacks microtubules)- protein
  structure

6
Reproduction and Adaptation

• Most reproduce in 1-3 hours
• Some can form endospore protection in harsh
  environment (Bacillus anthracis)- can remain
  dormant for centuries

7
Internal Organization

• Some have specialized membranes that perform
  metabolic functions
• Circular DNA, different ribosomes, etc.

8
Autotrophs

• Produce their own carbon molecules
• Photoautotrophs photosynthesis
• Chemoautotrophs inorganic chemicals

9
Heterotrophs

• Obtain carbon from other sources
• Photoheterotrophs can do photosynthesis
• Chemoheterotrophs obtain energy and carbon from
  exterior sources

10
(No Transcript)
11
Prokaryotes obtain nourishment in a variety of
ways

• Some are individualists (obtain their own food,
  energy)
• Some are cooperative (some cells perform some
  processes, while other cells perform other
  processes)
• Biofilms cells in a colony adhere to each other
  and their substrate (function as one)
• Some cross-species cooperation possible

12
(No Transcript)
13
Prokaryotes help clean up the environment

• Natural situations many prokaryotes recycle
  nitrogen, etc. through natural systems
• Bioremediation remove pollutants from soil, air,
  or water with help of organisms
• Prokaryotes help clean up oil spills, clean sewage

14
(No Transcript)
15
Bacteria and Archaea

• Two kinds of prokaryotes bacteria and archaea
• Current theory Archaea and Eukaryotes have
  evolved from the same ancestor
• Differences cell wall components (bacteria has
  peptidoglycan, archaea doesnt have
  peptidoglycan) different plasma membrane lipids,
  etc.

16
(No Transcript)
17
Archaea thrive in extreme environments- and in
other habitats

• Extreme halophiles salt lovers
• Salt-lake
• Extreme thermophiles heat lovers
• Hot springs, deep ocean vents (over 100 C)
• Methanogens anaerobic conditions
• Mud at bottom of lakes (swamp bubbling)
• Almost everywhere else, too!

18
Methanogens
Thermophiles
19
(No Transcript)
20
Bacteria

• Proteobacteria gram-negative
• 5 of the 9 groups

• Gram-positive bacteria

21
Bacteria

• Cyanobacteria
• Plant-like, oxygen producing photosynthesis

• Chlamydias

22
Bacteria

• Spirochetes helical (syphilis, Lyme disease)

23
(No Transcript)
24
Some bacteria cause disease

• Pathogenic bacteria cause about ½ of all human
  diseases
• Most produce poison
• Exotoxin secreted by bacterial cell
  (Staphlococcus aureus, E. coli O157H7)
• Endotoxin components of outer membrane of gram-
  bacteria (Salmonella)
• Sanitation has reduced threat, as has education

25
Staph
26
How to Win a Nobel Prize
27
Bacteria can be used as biological weapons

• Millionth of a gram of Bacillus anthracis can
  kill a person (anthrax)
• Gram of aerosolized botulinum toxin can kill 1.5
  million people (Clostridium botulinum)

28
(No Transcript)
29
The eukaryotic cell probably originated as a
community of prokaryotes

• Widely accepted view two processes
• Membrane infolding
• Created endomembrane system
• Endosymbiosis
• Mitochondria and chloroplasts were at one time
  free-living prokaryotes (they are very similar to
  modern day prokaryotes)
• Were engulfed by eukaryotic cells (explains extra
  membranes)

30
(No Transcript)
31
(No Transcript)
32
Protists are an extremely diverse assortment of
eukaryotes

• Probably not 1 kingdom
• Algae photosynthesis
• Protozoans heterotrophic
• Most are aquatic, unicellular
• Have membrane enclosed organelles, cilia and
  flagella have 92 microtubule arrangement

33
(No Transcript)
34
Chromalveolates

• Autotrophs
• Diatoms unicellular algae with glassy walls
• Dinoflagellates usually photosynthetic,
  unicellular, cause red tide
• Brown algaes multicellular,
  called seaweed, kelp

35
Chromalveolates

• Heterotrophs
• Water molds unicellular, decomposers
• Ciliates move, feed using cilia

36
Rhizarians

• Amoebas
• Use pseudopods for movement, feeding
• Some have internal or external structures that
  are rigid or semi-rigid

37
Excavata

• Have an excavated feeding groove
• Many lack functional ETC in mitochondria, so use
  anaerobic pathways
• Many are human pathogens, parasites

38
Unikonts

• More amoebas (free-living, test free)
• Slime molds
• Plasmodial huge, but unicellular bright colors
• Cellular start as amoeboid cells, form glob that
  produces spores

39
(No Transcript)
40
(No Transcript)
41
Archaeplastids

• Most are autotrophic, colored algaes
• Red algae some have hard outer parts, others
  commercially important
• Green algae unicellular to multicellular, very
  similar to plants (NOT plants)

42
(No Transcript)
43
Multicellularity evolved several times in
eukaryotes

• Unicellular organisms all of lifes activities
  occur within a single cell
• Multicellular organisms specialized cells for
  specialized processes
• Process
• Ancestral colony formed
• Cells in colony become specialized
• Specialization continues until formation of sex
  cells

44
(No Transcript)