Download chapt28_lecture - OCC

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Carbapenem-resistant enterobacteriaceae wikipedia , lookup

Sexually transmitted infection wikipedia , lookup

Traveler's diarrhea wikipedia , lookup

Antibiotics wikipedia , lookup

Neisseria meningitidis wikipedia , lookup

Transcript
Prokaryotes
Chapter 28
2
The First Cells
Prokaryote Video
Microfossils are fossilized forms of
microscopic life
-Oldest are 3.5 billion years old
3
The First Cells
Stromatolites are mats of cyanobacterial
cells that trap mineral deposits
-Oldest are 2.7 billion years old
4
The First Cells
Isotopic analysis of carbon-12 in fossils
suggests that carbon fixation was active
as much as 3.8 BYA
Biomarkers are organic molecules of
biological origin
-Lipids were found in ancient rocks
-This indicates that cyanobacteria are
at least 2.7 billion years old
5
Prokaryotic Diversity
Prokaryotes are the oldest, and structurally
simplest forms of life
Prokaryotes are ubiquitous
Less than 10% of species are known
Bacteria (also called eubacteria)
Archaea (formerly called archaebacteria)
-Many archaeans are extremophiles
6
Prokaryotic Features
Unicellularity
-Most are single-celled
-Some can form complex biofilms
Cell size
-Most are less than 1 mm in diameter
Chromosome
-Single circular double-stranded DNA
-Found in the nucleoid
7
Prokaryotic Features
Internal compartmentalization
-No membrane-bounded organelles
Flagella
-Simple in structure; spin like propellers
Cell division
-Most divide by binary fission
Genetic recombination
-Occurs through horizontal gene transfer
8
9
Prokaryotic Features
Metabolic diversity
-Two types of photosynthesis
-Oxygenic = Produces oxygen
-Anoxygenic = Nonoxygen producing
- E.g: Sulfur and sulfate
-Chemolithotrophic prokaryotes derive
energy from inorganic molecules
10
Marsh
• Detritus = Organic material
• Bacteria break down detritus through
anaerobic processes creating sulfur
dioxide = rotten egg smell.
11
Molecular Classification
12
Prokaryotic Shapes
Most prokaryotes have one of 3 basic shapes
-Bacillus = Rod-shaped
-Coccus = Spherical
-Spirillum = Helical-shaped
13
The Bacterial Cell Wall
Maintains shape and protects the cell from
swelling and rupturing
Consists of peptidoglycan
-Polysaccharides cross-linked with peptides
Archaea do not possess peptidoglycan
-Some have pseudopeptidoglycan
Cell wall is the basis of the Gram stain
14
The Bacterial Cell Wall
15
The Bacterial Cell Wall
Two main types
-Gram-positive bacteria
-Thick peptidoglycan
-Teichoic and lipoteichoic acids
-Gram-negative bacteria
-Thin peptidoglycan
-Have an outer membrane
-Contains lipopolysaccharide
16
The Bacterial Cell Wall
17
External Layers
S-layer
-A rigid paracrystalline layer found in some
bacteria and archaea
-Aids in attachment
Capsule
-A gelatinous layer found in some bacteria
-Aids in attachment
-Protects from the immune system
18
Bacterial Appendages
Pili
-Short, hairlike structures
-Found in Gram-negative bacteria
-Aid in attachment and conjugation
Flagella
-Long, helical structures
-Composed of the protein flagellin
-Involved in locomotion
19
Bacterial Appendages
20
Internal Structure
Nucleoid region
-Contains the single, circular chromosome
-May also contain plasmids
Ribosomes
-Smaller than those of eukaryotes and differ
in protein and RNA content
-Targeted by antibacterial antibiotics
21
Mutation
Mutations can arise spontaneously in bacteria
-Also caused by radiation and chemicals
Mutations (and plasmids) can spread rapidly
in a population
-Negative consequences for humans
-For example:
-Methicillin-resistance
Staphylococcus aureus (MRSA)
-Vancomycin-resistant
Staphylococcus aureus (VRSA)
22
Prokaryotic Metabolism
Acquisition of Carbon
-Autotrophs = From inorganic CO2
-Heterotrophs = From organic molecules
Acquisition of Energy
-Chemolithotrophs = From inorganic
chemicals
-Phototrophs = From sunlight
23
Prokaryotic Metabolism
Photoautotrophs
-Cyanobacteria
Chemolithoautotrophs
-Nitrifiers
Photoheterotrophs
-Purple and green nonsulfur bacteria
Chemoheterotrophs
-Majority of prokaryotes
-Use organic molecules for C and energy
24
Human Bacterial Disease
In the early 20th century, infectious diseases
killed 20% of children before the age of five
-Sanitation and antibiotics considerably
improved the situation
In recent years, however, many bacterial
diseases have appeared and reappeared
25
Human Bacterial Disease
Tuberculosis
-Mycobacterium tuberculosis
-A scourge for
thousands of years
-Afflicts the
respiratory system
-Mutidrug-resistant
(MDR) strains are
very alarming
26
Human Bacterial Disease
Dental caries (tooth decay)
-Plaque consists of bacterial biofilms
-Streptococcus ferments sugar to lactic acid
-Tooth enamel degenerates
Peptic ulcers
-Helicobacter pylori is the main cause
-Treated with antibiotics
27
Sexually transmitted diseases (STDs)
Gonorrhea
-Neisseria gonorrhoeae
-Can pass from mom to baby via birth canal
-Can cause pelvic inflammatory disease (PID)
Chlamydia
-Chlamydia trachomatis
-“Silent STD”
-Can cause PID and heart disease
28
Sexually transmitted diseases (STDs)
Syphilis
-Treponema pallidum
-Can pass from mom to baby via birth canal
-Four distinct stages
-Primary - Chancre
-Secondary - Rash
-Tertiary - Latency
-Quaternary - Heart and nerve damage
29
Sexually transmitted diseases (STDs)
30
Beneficial Prokaryotes
Prokaryotes are crucial to chemical cycles
-Decomposers release a dead organism’s
atoms to the environment
-Photosynthesizers fix carbon into sugars
-Nitrogen fixers reduce N2 to NH3
(ammonia)
31
Bacterial Decomposition in
Wastewater Treatment
32
Beneficial Prokaryotes
Prokaryotes may live in symbiotic
relationships with eukaryotes
-Mutualism = Both parties benefit
-Nitrogen-fixing bacteria on plant roots
-Cellulase-producing bacteria in animals
-Commensalism = One organism benefits
and the other is unaffected
-Parasitism = One organism benefits and
the other is harmed
33
Beneficial Prokaryotes
Bacteria are used in genetic engineering
- “Biofactories” that produce various
chemicals, including insulin and antibiotics
Bacteria are used for bioremediation
-Remove pollutants from water, air and soil
-Exxon Valdez oil spill
34
Beneficial Prokaryotes
35
Chapter 29 - Protists
• Protists are the most diverse of the four
eukaryotic kingdoms
– Unicellular, colonial and multicellular groups
•
•
•
•
Some are photosynthetic (like plants)
Autotrophic & Heterotrophic
Found anywhere in the water
Video Clip
36
37
38
39