Download Gram-Positive Bacteria

LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 27
Bacteria and Archaea
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Overview: Masters of Adaptation
• Utah’s Great Salt Lake can reach a salt
concentration of 32%
• Its pink color comes from living prokaryotes
© 2011 Pearson Education, Inc.
• Prokaryotes thrive almost everywhere, including
places too acidic, salty, cold, or hot for most
other organisms
– microscopic
– more in a handful of fertile soil than the number of
people who have ever lived
• Prokaryotes are divided into two domains:
bacteria and archaea
Video: Tubeworms
© 2011 Pearson Education, Inc.
Concept 27.1: Structural and functional
adaptations contribute to prokaryotic
success
• Earth’s first organisms
• unicellular
• prokaryotic cells: 0.5–5
µm
– Eukaryotic Cells:
10–100 µm
• Shape: spheres
(cocci), rods (bacilli),
and spirals
© 2011 Pearson Education, Inc.
Cell-Surface Structures
• Cell Wall: maintains cell shape, cell protection,
and prevents it from bursting in a hypotonic
environment
– contain peptidoglycan: a network of sugar polymers
cross-linked by polypeptides
• Archaea: lack peptidoglycan
• Gram stain: classify bacteria
– Gram-positive: simpler walls with a large amount of
peptidoglycan
– Gram-negative: less peptidoglycan and an outer
membrane that can be toxic
© 2011 Pearson Education, Inc.
Figure 27.3
(a) Gram-positive bacteria: peptidoglycan traps crystal violet.
Gram-positive
bacteria
(b) Gram-negative bacteria: crystal violet is easily rinsed
away, revealing red dye.
Gram-negative
bacteria
Carbohydrate portion
of lipopolysaccharide
Cell
wall
Peptidoglycan
layer
Cell
wall
Plasma
membrane
10 m
Outer
membrane
Peptidoglycan
layer
Plasma membrane
• Many antibiotics target peptidoglycan and
damage bacterial cell walls
• Gram-negative bacteria: > antibiotic resistant
• capsule: protein layer that covers many
prokaryotes
• Fimbriae: stick to their substrate or other
individuals in a colony
• Pili (or sex pili) are longer than fimbriae and
allow prokaryotes to exchange DNA
© 2011 Pearson Education, Inc.
Figure 27.5
Fimbriae
1 m
Motility
• Taxis: ability to move toward or away from a
stimulus
• Chemotaxis is the movement toward or away
from a chemical stimulus
– Flagella: scattered about the surface or concentrated
at one or both ends
Video: Prokaryotic Flagella (Salmonella typhimurium)
© 2011 Pearson Education, Inc.
Figure 27.6
Flagellum
Filament
Hook
Motor
Cell wall
Plasma
membrane
Rod
Peptidoglycan
layer
20 nm
Internal Organization and DNA
• lack complex compartmentalization
• Some have specialized membranes that
perform metabolic functions
– infoldings of the plasma membrane
•
•
•
•
less DNA than the eukaryotes
circular chromosome
located in the nucleoid region
Plasmid: smaller rings of DNA
© 2011 Pearson Education, Inc.
Figure 27.7
1 m
0.2 m
Respiratory
membrane
Thylakoid
membranes
(a) Aerobic prokaryote
(b) Photosynthetic prokaryote
Figure 27.8
Chromosome
Plasmids
1 m
Reproduction and Adaptation
• prokaryotic reproduction:
– They are small
– They reproduce by binary fission
– They have short generation times
• Endospore: metabolically inactive, which
can remain viable in harsh conditions for
centuries
• Their short generation time allows prokaryotes
to evolve quickly
© 2011 Pearson Education, Inc.
Figure 27.9
Endospore
Coat
0.3 m
Figure 27.10
EXPERIMENT
Daily serial transfer
0.1 mL
(population sample)
Old tube
(discarded
after
transfer)
New tube
(9.9 mL
growth
medium)
Population growth rate
(relative to ancestral population)
RESULTS
1.8
1.6
1.4
1.2
1.0
0
5,000
10,000
15,000
Generation
20,000
Concept 27.2: Rapid reproduction,
mutation, and genetic recombination
promote genetic diversity in prokaryotes
• Three factors contribute to this genetic diversity:
– Rapid reproduction
– Mutation
– Genetic recombination
© 2011 Pearson Education, Inc.
Transformation, Transduction, & Conjugation
• Transformation: prokaryotic cell takes up and
incorporate foreign DNA from the surrounding
environment
• Transduction: movement of genes between
bacteria by bacteriophages (viruses that infect
bacteria)
• Conjugation: genetic material is transferred
between prokaryotic cells
– A donor cell attaches to a recipient by a pilus, pulls it
closer, and transfers DNA
© 2011 Pearson Education, Inc.
Figure 27.11-4
Phage
A B
Donor cell
A B
A
Recombination
A
A B
A B
Recipient
cell
Recombinant cell
Figure 27.12
1 m
Sex pilus
Concept 27.3: Diverse nutritional and
metabolic adaptations have evolved in
prokaryotes
• Prokaryotes can be categorized by how they
obtain energy and carbon
–
–
–
–
Phototrophs obtain energy from light
Chemotrophs obtain energy from chemicals
Autotrophs require CO2 as a carbon source
Heterotrophs require an organic nutrient to make
organic compounds
© 2011 Pearson Education, Inc.
Metabolism
• Prokaryotic metabolism varies with respect to O2
– Obligate aerobes require O2 for cellular
respiration
– Obligate anaerobes are poisoned by O2 and
use fermentation or anaerobic respiration
– Facultative anaerobes can survive with or
without O2
– In nitrogen fixation, some prokaryotes
convert atmospheric nitrogen (N2) to
ammonia (NH3)
© 2011 Pearson Education, Inc.
Archaea
• Archaea share certain traits with bacteria and
other traits with eukaryotes
– extremophiles: archaea that live in extreme
environments
•
•
halophiles highly saline
Thermophiles: very hot environments
– Methanogens: live in swamps and marshes
and produce methane as a waste product
•
poisoned by O2
© 2011 Pearson Education, Inc.
Figure 27.16
Proteobacteria: gram • Alpha Proteobacteria
– Rhizobium: forms root nodules in legumes and fixes
atmospheric N2
– Agrobacterium: produces tumors in plants and is used
in genetic engineering
• Beta Proteobacteria: soil bacterium converts NH4+ to NO2–
• Gamma Proteobacteria
– Pathogens: Legionella, Salmonella, and Vibrio cholerae
– Escherichia coli
• Epsilon Proteobacteria: Campylobacter (blood poisoning)
and Helicobacter pylori (stomach ulcers)
© 2011 Pearson Education, Inc.
• Chlamydias: blindness and nongonococcal
urethritis by sexual transmission
• Spirochetes:Treponema pallidum
(syphilis) and Borrelia burgdorferi (Lyme
disease)
• Cyanobacteria: generate O2
– Plant chloroplasts
© 2011 Pearson Education, Inc.
Gram-Positive Bacteria
• Gram-positive bacteria include
–
–
–
–
Actinomycetes, which decompose soil
Bacillus anthracis, the cause of anthrax
Clostridium botulinum, the cause of botulism
Some Staphylococcus and Streptococcus,
which can be pathogenic
– Mycoplasms, the smallest known cells
© 2011 Pearson Education, Inc.
Chemical Recycling
• Chemoheterotrophic prokaryotes:
decomposers, breaking down dead organisms
and waste products
• Prokaryotes: increase the availability of nitrogen,
phosphorus, and potassium for plant growth
• Prokaryotes can also “immobilize” or decrease
the availability of nutrients
© 2011 Pearson Education, Inc.
Ecological Interactions
• Symbiosis: two species live in close contact: a
larger host and smaller symbiont
– Mutualism: both benefit
– Commensalism: one benefits while neither harming
nor helping the other
– parasitism, an organism called a parasite harms but
does not kill its host
• pathogens
© 2011 Pearson Education, Inc.
Mutualistic & Pathogenic Bacteria
• Human intestines are home to about 500–1,000
species of bacteria
• Many of these are mutalists and break down
food that is undigested by our intestines
• Prokaryotes cause about half of all human
diseases
– For example, Lyme disease is caused by a
bacterium and carried by ticks
© 2011 Pearson Education, Inc.
Figure 27.20
5 m
Prokaryotes in Research and Technology
• DNA technology
– E. coli is used in gene cloning
– Agrobacterium tumefaciens: produce transgenic
plants
• make natural plastics
• Bioremediation: organisms to remove pollutants
from the environment
• Produce vitamins, antibiotics, and hormones
• Produce ethanol from waste biomass
© 2011 Pearson Education, Inc.
Figure 27.21
(a)
(c)
(b)
LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 28
Protists
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Concept 28.1: Most eukaryotes are
single-celled organisms
• Protists constitute a polyphyletic group, and
Protista is no longer valid as a kingdom
• Protists are eukaryotes
– organelles and are more complex than prokaryotic cells
– Most are unicellular, but there are some colonial and
multicellular species
© 2011 Pearson Education, Inc.
• Protists, the most nutritionally diverse of all
eukaryotes, include
– Photoautotrophs, which contain chloroplasts
– Heterotrophs, which absorb organic molecules or
ingest larger food particles
– Mixotrophs, which combine photosynthesis and
heterotrophic nutrition
• Reproduce: asexually, sexually, or by
meiosis and fertilization
© 2011 Pearson Education, Inc.
Endosymbiosis in Eukaryotic Evolution
• protist diversity  endosymbiosis
• Endosymbiosis: a unicellular organism engulfs
another cell and becomes an organelle in host cell
– Mitochondria (aerobic prokaryote) & Plastids
(photosynthetic cyanobacterium)
© 2011 Pearson Education, Inc.
Figure 28.2c
Secondary
endosymbiosis
Plastid
Euglenids
Secondary
endosymbiosis
Green alga
Chlorarachniophytes
Types of Protist
• Dinoflagellates: two flagella
– both marine and freshwater phytoplankton
– Toxic “red tides” are caused by dinoflagellate blooms
• Apicomplexans: parasites of animals
– Plasmodium: malaria
– Approximately 900,000 people die each year from
malaria
• Brown algae: kelp or sea-weed
• Oomycetes include water molds, white rusts, and
downy mildews
– potato blight caused by Phytophthora infestans
© 2011 Pearson Education, Inc.
Figure 28.10-3
Inside mosquito
Inside human
Merozoite
Sporozoites
(n)
Liver
Liver
cell
Apex
Oocyst
MEIOSIS
Red blood
cell
Merozoite
(n)
Zygote
(2n)
0.5 m
Red blood
cells
FERTILIZATION
Gametes
Gametocytes
(n)
Key
Haploid (n)
Diploid (2n)
Diatoms
• Diatoms are unicellular algae with a unique twopart, glass-like wall of hydrated silica
• Diatoms usually reproduce asexually, and
occasionally sexually
© 2011 Pearson Education, Inc.
Figure 28.3c
50 m
Diatom diversity
Concept 28.5: Red algae and green algae are
the closest relatives of land plants
Concept 28.6: Unikonts include protists that
are closely related to fungi and animals
Concept 28.7: Protists play key roles in
ecological communities
© 2011 Pearson Education, Inc.
Symbiotic Protists
• Some protist symbionts benefit their hosts
– Dinoflagellates nourish coral polyps that build
reefs
– Wood-digesting protists digest cellulose in the gut
of termites
© 2011 Pearson Education, Inc.