0 PROKARYOTES 167 Prokaryotes have inhabited Earth for billions of years Prokaryotes are the oldest lifeforms And remain the most numerous and widespread organisms Colorized SEM 650 ID: 775253
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Slide1
Chapter 16
The Origin and Evolution of Microbial Life: Prokaryotes and Protists
0
Slide2PROKARYOTES
16.7 Prokaryotes have inhabited Earth for billions of yearsProkaryotes are the oldest life-formsAnd remain the most numerous and widespread organisms
Colorized SEM 650
Figure 16.7
Slide3Three Domains – Archaea, Bacteria, Eukarya
Slide416.8
Bacteria and
archaea
are the two main branches of prokaryotic evolution
Domains Bacteria and
Archaea
Are distinguished on the basis of nucleotide sequences and other molecular and cellular features
Slide5Differences between Bacteria and Archaea
Table 16.8
Slide616.9 Prokaryotes come in a variety of shapesProkaryotes may be shaped asSpheres (cocci) Rods (bacilli)Curves or spirals (vibrio or spirochaete)
Colorized SEM 12,000
Colorized SEM 9,000
Colorized SEM 3,000
Figure 16.9A–C
Slide716.10 Various features contribute to the success of prokaryotes
External Structures
Cell wall
Pili
Flagella
Reproduction and adaptation
Specialized internal structures
Form colonies
Varied methods of obtaining food
Slide8External StructuresThe cell wallIs one of the most important features of nearly all prokaryotesIs covered by a sticky capsule
Colorized TEM 70,000
Capsule
Figure 16.10A
Slide9Some prokaryotesStick to their substrate with pili
Colorized TEM 16,000
Pili
Figure 16.10B
Slide10MotilityMany bacteria and archaeaAre equipped with flagella, which enable them to move
Flagellum
Plasma
membrane
Cell wall
Rotary movement of
each flagellum
Colorized TEM 14,000
Figure 16.10C
Slide11Reproduction and Adaptation
Prokaryotes
Have the potential to reproduce quickly in favorable environments
Slide12Some prokaryotes can withstand harsh conditionsBy forming endospores
TEM 34,000
Endospore
Figure 16.10D
Slide13Internal OrganizationSome prokaryotic cellsHave specialized membranes that perform metabolic functions
Figure 16.10E
Respiratory
membrane
Thylakoid
membrane
TEM 45,000
TEM 6,000
Slide1416.11
Prokaryotes obtain nourishment in a variety of ways
As a group
Prokaryotes exhibit much more nutritional diversity than eukaryotes
Slide15Types of Nutrition
Autotrophs
make their own organic compounds from inorganic sources
Photoautotrophs
harness sunlight for energy and use CO
2
for carbon
Chemoautotrophs
obtain energy from inorganic chemicals instead of sunlight
Slide16Heterotrophs obtain their carbon atoms from organic compoundsPhotoheterotrophs can obtain energy from sunlightChemoheterotrophs are so diverse that almost any organic molecule can serve as food for some species
Figure 16.11A
Slide17Nutritional classification of organisms
Table 16.11
Slide18Metabolic CooperationIn some prokaryotesMetabolic cooperation occurs in surface-coating colonies called biofilms
Colorized SEM 13,000
Figure 16.11B
Slide1916.12 Archaea thrive in extreme environments (extremophiles) — and in other habitatsArchaea are common inSalt lakes, acidic hot springs, deep-sea hydrothermal vents
Figure 16.12A, B
Slide20Archaea are also a major life-form in the ocean
Plankton dispersal
Phytoplankton
Slide2116.13 Bacteria include a diverse assemblage of prokaryotesBacteria are currently organized into several subgroups, includingProteobacteria ChlamydiasSpirochetes
LM 13,000
Colorized TEM 5,000
Figure 16.13A, B
Slide22Gram-positive bacteriaCyanobacteria, which photosynthesize in a plantlike way
Figure 16.13C, D
Colorized SEM 2,800
LM 650
Photosynthetic
cells
Nitrogen-fixing
cells
Colorized SEM 2,8000
Slide23CONNECTION
16.14 Some bacteria cause diseasePathogenic bacteria cause disease by producingExotoxins or endotoxins
SEM 12,000
Spirochete
that causesLyme disease
“Bull’s-eye”rash
Tick that carriesthe Lyme diseasebacterium
SEM 2,800
Figure 16.14A, B
Slide24Figure 16.15
CONNECTION
16.15
Bacteria can be used as biological weapons
Bacteria, such as the species that causes anthrax
Can be used as biological weapons
Slide25CONNECTION
16.16 Prokaryotes help recycle chemicals and clean up the environmentBioremediationIs the use of organisms to clean up pollution
Slide26Prokaryotes are decomposers inSewage treatment and can clean up oil spills and toxic mine wastes
Figure 16.16A, B
Liquid wastes
Outflow
Rotating
spray arm
Rock bed
coated with
aerobic
bacteriaand fungi
Slide27PROTISTS
16.17
The
eukaryotic cell probably originated as a community of prokaryotes
Eukaryotic cells
Evolved from prokaryotic cells more than 2 billion years ago
Slide28The nucleus and
endomembrane
system
Probably evolved from
infoldings
of the plasma membrane
Mitochondria and chloroplasts
Probably evolved from aerobic and photosynthetic
endosymbionts
, respectively
Slide29Endosymbiotic Theory
A model of the origin of eukaryotes
Cytoplasm
Ancestral prokaryote
Plasma
membrane
Endoplasmic
reticulum
Nucleus
Nuclearenvelope
Cell with nucleus andendomembrane system
Membrane infolding
Aerobic heterotrophicprokaryote
Ancestral host cell
Endosymbiosis
Mitochondrion
Chloroplast
Photosyntheticeukaryotic cell
Photosyntheticprokaryote
Mitochondrion
Somecells
Figure 16.17
Slide3016.18 Protists are an extremely diverse assortment of eukaryotesProtistsAre mostly unicellular eukaryotesMolecular systematicsIs exploring eukaryotic phylogeny
LM 275
Figure 16.18
Slide31How are Protists classified?
16.19 A tentative phylogeny of eukaryotes includes multiple clades of protistsThe taxonomy of protists Is a work in progress
Diplomonads
Euglenozoans
Dinoflagellates
Apicomplexans
Ciliates
Water molds
Diatoms
Brown algae
Amoebas
Plasmodial slime molds
Cellular slime molds
Fungi
Choanoflagellates
Animals
Red algae
Green algae
Closest algal relatives of plants
Plants
Alveolates
Stramenopila
Amoebozoa
Ancestral eukaryote
Figure 16.19
Slide3216.20 Diplomonads and euglenozoans include some flagellated parasitesThe parasitic GiardiaIs a diplomonad with highly reduced mitochondria
Colorized SEM 4,000
Figure 16.20A
Slide33EuglenozoansInclude trypanosomes and Euglena
Colorized SEM 1,300
Colorized SEM 1,300
Figure 16.20B, C
Slide3416.21 Alveolates have sacs beneath the plasma membrane and include dinoflagellates, apicomplexans, and ciliatesDinoflagellatesAre unicellular algae
SEM 2,300
Figure 16.21A
Slide35Apicomplexans are parasitesSuch as Plasmodium, which causes malaria
Red blood cell
Apex
TEM 26,000
Figure 16.21B
Slide36CilliatesUse cilia to move and feed
Cilia
Macronucleus
LM 60
Figure 16.21C
Slide3716.22 Stramenopiles are named for their “hairy” flagella and include the water molds, diatoms, and brown algaeThis clade includesFungus-like water molds
Figure 16.22A
Slide38Photosynthetic, unicellular diatoms
LM 400
Figure 16.22B
Slide39Brown algae, large complex seaweeds
Figure 16.22C
Slide4016.23 Amoebozoans have pseudopodia and include amoebas and slime moldsAmoebasMove and feed by means of pseudopodia
LM 185
Figure 16.23A
Slide41A plasmodial slime mold is a multinucleate plasmodium That forms reproductive structures under adverse conditions
Figure 16.23B
Slide42Cellular slime moldsHave unicellular and multicellular stages
Slug-like aggregate
45
LM 1,000
15
Amoeboid cells
Reproductive
structure
Figure 16.23C
Slide4316.24 Red algae and green algae are the closest relatives of land plantsRed algaeContribute to coral reefs
Figure 16.24A
Slide44Green algaeMay be unicellular, colonial, or multicellular
Chlamydomonas
Volvox
colonies
LM 80
LM 1,200
Figure 16.24B
Slide45The life cycles of many algaeInvolve the alternation of haploid gametophyte and diploid sporophyte generations
Mitosis
Male
gametophyte
Gametes
Spores
Mitosis
Meiosis
Fusion of
gametes
Femalegametophyte
Zygote
Sporophyte
Mitosis
Haploid (n)
Diploid (2n)
Key
Figure 16.24C
Slide4616.25 Multicellularity evolved several times in eukaryotesMulticellularity evolved in several different lineagesProbably by specialization of the cells of colonial protists
Figure 16.25
Unicellular protist
Colony
Early multicellular organism
with specialized, interdepen-
dent cells
Later organism thatproduces gametes
Food-synthesizingcells
Locomotorcells
Somaticcells
Gamete
1
2
3
Slide47Multicellular life arose over a billion years ago