Campbell reece chapter 27
This presentation is the property of its rightful owner.
Sponsored Links
1 / 106

BACTERIA & ARCHAEA PowerPoint PPT Presentation


  • 77 Views
  • Uploaded on
  • Presentation posted in: General

CAMPBELL & REECE CHAPTER 27. BACTERIA & ARCHAEA. PROKARYOTIC ADAPTATIONS. typical prokaryote: 0.5 -5 microns unicellular variety of shapes cocci (spherical) bacilli (rods) spirochetes (corkscrews). Cell-Surface Structures. nearly all have cell wall maintains shape protects cell

Download Presentation

BACTERIA & ARCHAEA

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Campbell reece chapter 27

CAMPBELL & REECE

CHAPTER 27

BACTERIA & ARCHAEA


Prokaryotic adaptations

PROKARYOTIC ADAPTATIONS

  • typical prokaryote:

    • 0.5 -5 microns

    • unicellular

    • variety of shapes

      • cocci (spherical)

      • bacilli (rods)

      • spirochetes (corkscrews)


Cell surface structures

Cell-Surface Structures

  • nearly all have cell wall

    • maintains shape

    • protects cell

    • plasmolyze in hypertonic solution

      • water loss inhibits cell division hence salt used as food preservative (ham)


Cell wall structure

Cell Wall Structure

Prokaryotes

Eukaryotes

cell walls mostly cellulose or chitin

ARCHAEA

(-) peptidoglycan

(+) variety polysaccharides & proteins

  • bacterial cell walls contain peptidoglycan: a polymer made of sugars cross-linked with short polypeptides


Peptidoglycan

Peptidoglycan


Gram staining

Gram Staining

  • used to classify many bacteria as gram + or gram –

  • + or – staining due to differences in cell wall composition


Bacteria archaea

Gram +

Gram -

more complex

less peptidoglycan

+ outer membrane with lipopolysaccharides

  • simpler cell walls

  • more peptidoglycan


Bacteria archaea

Gram +

Gram -


Bacteria archaea

Gram + Rods

Gram - Rods


Medical implications of gram stain

Medical Implications of Gram Stain

Gram +

Gram -

many strains virulent:

tends to be:

toxic (fever, shock more likely)

drug resistance

  • some strains virulent

  • some drug resistance (staph)


Penicillin

Penicillin

  • works by inhibiting peptidoglycan cross-linking  makes cell nonfunctional

  • since none in eukaryotic cells  does not harm them


Penicillin1

Penicillin

  • Which infection would more likely respond to treatment with pcn?


Prokaryotic capsules

Prokaryotic Capsules

  • dense, well-defined outermost layer (called slime layer if not well-defined)

  • Sticky

    • stick to each other in a colony or to infected individual’s cells

  • make it more difficult for immune system to get to bacterial cell


Capsules

Capsules


Fimbriae

Fimbriae

  • used to stick to host cells

  • shorter & more numerous than pili


Bacteria archaea

Pili

  • appendages that pull cells together prior to DNA transfer between cells

  • aka sex pili


Bacteria motility

Bacteria Motility

  • taxis: a directed movement toward or away from a stimulus

  • chemotaxis: movement toward a chemical (+ chemotaxis) or away from a toxic chemical (- chemotaxis)


Flagella

Flagella

  • most common structure used for prokaryotic motility


Flagella1

Flagella

  • not covered by extension of plasma membrane as in eukaryotic cell flagellum

  • smaller (~ 1/10th width of eukaryotic flagella)

  • Bacteria & Archaea flagella similar in size & rotation mechanism but composed of different proteins


Flagella2

Flagella

  • all these differences suggest flagella arose independently in all 3 Domains

  • so are analogous structures not homologous structures


Flagella3

Flagella

Archaea

Bacteria


Bacterial flagella

Bacterial Flagella

  • 3 main parts:

  • motor

  • hook

  • filament


Bacterial flagella1

Bacterial Flagella

  • evidence indicates it started as a simpler structure that has been modified in steps over time

  • (like evolution of eye) each step would have had to have been useful

  • analysis shows only ~1/2 proteins in flagellum necessary for it to function


Bacterial flagella2

Bacterial Flagella

  • analysis shows only ~1/2 proteins in flagellum necessary for it to function

  • 19 of 21 proteins in flagella are modified versions of proteins that perform other tasks in bacteria

  • this is example of exaption: process in which existing structures take on new functions through descent with modification


Dna in prokaryotic cells

DNA in Prokaryotic Cells

  • most have less DNA than eukaryotic cell

  • circular chromosome with many fewer proteins

  • loop located in nucleoid

  • most also have a plasmid: smaller ring(s) of independently replicating DNA


Dna in prokaryotic cells1

DNA in Prokaryotic Cells


Inner membranes in prokaryotic cells

Inner Membranes in Prokaryotic Cells

  • So how do some prokaryotic cells undergo photosynthesis and cellular respiration if they do not have membrane-bound organelles?


Inner membranes in prokaryotic cells1

Inner Membranes in Prokaryotic Cells


Reproduction of prokaryotic cells

Reproduction of Prokaryotic Cells

  • BINARY FISSION


Bacterial reproduction

Bacterial Reproduction

  • many bacteria can divide in 1- 3 hrs. (some in 20 min)

  • factors that slow down reproduction:

    • loss of nutrients

    • toxic metabolic waste

    • competition with other bacteria

    • eaten by predators


Survivors in extreme environments

Survivors in Extreme Environments

  • Halobacterium

    • rod-shaped

    • Archaea

    • lives in 4M saline (or higher)


Endospores

Endospores

  • developed by certain bacteria to withstand harsh conditions

  • resistant cells develop when essential nutrients lacking


Endospores1

Endospores

  • survive boiling water

  • remain dormant & viable for centuries


Prokaryotic evolution

Prokaryotic Evolution

  • short generations (up to 20,000 in 8 yrs)

  • adapt rapidly

  • populations have high genetic diversity

  • have been around for 3.5 billion yrs


Genetic diversity

Genetic Diversity

  • Factors that promote genetic diversity:

  • rapid reproduction

  • mutation

  • genetic recombination


Rapid reproduction mutation

Rapid Reproduction & Mutation

  • because generations are so short even 1 mutation will produce many offspring and so increase genetic diversity which contributes to evolution


Genetic recombination

Genetic Recombination

  • the combining of DNA from 2 sources

  • occurs 3 ways in prokaryotes

    • transformation

    • transduction

    • conjugation


Transformation in prokaryotic cells

Transformation in Prokaryotic Cells

  • uptake of foreign DNA from its surroundings

  • many bacteria have cell-surface proteins that recognize DNA from closely related species & transport it into the cell


Transformation in prokaryotic cells1

Transformation in Prokaryotic Cells


Transduction in prokaryotic cells

Transduction in Prokaryotic Cells

  • bacteriophages (phages) carry prokaryotic genes from 1 host cell to another…..usually as result of “accidents” during replicative cycle


Transduction

Transduction


Conjugation plasmids

Conjugation & Plasmids

  • DNA is transferred between 2 prokaryotic cells (usually same species) that are temporarily joined by a mating bridge (from pilus)

  • transfer in 1 direction only

  • must have particular piece of DNA: F factor

  • DNA transferred either plasmid or section of loop DNA


Conjugation

Conjugation


Conjugation1

Conjugation


Plasmids antibiotic resistance

Plasmids & Antibiotic Resistance


Genetic recombination in prokaryotic cells

Genetic Recombination in Prokaryotic Cells


Metabolic adaptations in prokaryotic cells

Metabolic Adaptations in Prokaryotic Cells

  • phototrophs: obtain energy from light

  • chemotrophs: obtain energy from chemicals

  • autotrophs: need CO2 as carbon source

  • heterotrophs: require at least 1 organic nutrient to make other organic compounds


Oxygen

Oxygen

  • obligate aerobes: must use O2 for cellular respiration

  • obligate anaerobes: O2 is toxic to them (fermentation)

  • faculative anaerobes: use O2 when available but also carry out fermentation if have to


Oxygen prokaryotic cells

Oxygen & Prokaryotic Cells


Nitrogen metabolism

Nitrogen Metabolism

  • N essential to make a.a. & nucleic acids

  • Nitrogen Fixation

    • cyanobacterium & some methanogens

    • N2 from atmosphere  NH3  used by plants


Nitrogen fixation

Nitrogen Fixation


Metabolic cooperation

Metabolic Cooperation

  • heterocysts formation

  • biofilms

  • sulfate/methane consuming bacteria


Metabolic cooperation1

Metabolic Cooperation

  • Anabaena, a cyanobacterium carries genes for both photosynthesis and N fixation but any one cell can only do one or the other at same time

  • Anabaena forms filamentous chains, most carry out photosynthesis but a few, heterocysts only do N fixation


Anabaena filaments

Anabaena Filaments

  • heterocysts surrounded by thickened cell wall to prevent O2 from getting in (O2 turns off enzymes for N fixation)

  • intercellular connections allow heterocyst to send fixed N to neighboring cells


Anabaena filaments1

Anabaena Filaments


Biofilms

Biofilms

  • surface-coating colonies of different prokaryotic species

  • channels in biofilm allow nutrients to reach cells in interior (& wastes to leave)

  • cells secrete

  • signaling molecules  recruit nearby cells

  • polysaccharides & proteins that stick cells together


Biofilms1

Biofilms


Sulfate methane consumers

Sulfate/Methane Consumers

  • 1 archaea species that is a methane consumer forms ball-shaoedaggreagate with 1 sulfate consuming bacteria on ocean floor:

  • 1 uses wastes of other to obtain necessary nutrients


Prokaryotic phylogeny

Prokaryotic Phylogeny

  • b/4 technology made molecular systematics available prokaryotic organisms grouped by:

    • nutrition

    • shape

    • motility

    • Gram stain


Molecular systematics

Molecular Systematics

  • began comparing prokaryotic genes in the 1970’s

  • concluded some prokaryotes more closely related to eukaryotes than to rest of bacteria…..Bacteria & Archaea Domains


Polymerase chain reaction pcr

Polymerase Chain Reaction(PCR)

  • http://www.sumanasinc.com/webcontent/animations/content/pcr.html

  • used in 1980’s to make multiple copies of genes from prokaryotes in soil & water:

  • handful of soil could have up to 10,000 species of prokaryotes (overall there are only 7,800 with scientific names)


Comparison of 3 domains of life

Comparison of 3 Domains of Life


Archaea

ARCHAEA

  • share some traits with Bacteria, some with Eukarya

  • some unique traits too


Extremophiles

Extremophiles

1.extreme halophiles

  • live in highly saline environments

  • some tolerate high salinity

  • some require high salinity

    • proteins function best in extremely salty environments (die if salinity <9%) (ocean is 3.5%)


Halobacterium

Halobacterium


Extremophiles1

Extremophiles

2. extreme thermophiles

  • thrive in hot environments

  • Sulfolobuslive in sulfur-rich volcanic springs up to 90ºC

  • strain-121 lives in deep-sea hydrothermal vents up to 121ºC

    • Most cells would die: DNA would unfold, proteins would unwind; these cells have adaptations that avoid this.


Strain 121

strain-121


Extremophiles2

Extremophiles

3. methanogens

  • live in moderate environments

    • swamps, marshes

    • under ice in Greenland

    • in bovine colon, in termites

  • use carbon dioxide to oxidize H2 gas  produces energy & methane as a waste product

  • strict anaerobes


Methanogens

Methanogens


Archaea1

Archaea

  • new clades continue to be found


Bacteria

Bacteria

  • majority of prokaryotic species

  • have diverse nutritional & metabolic capabilities


Proteobacteria

Proteobacteria

  • a large & diverse clade

  • Gram (-)

  • (+) for photoautotrophs, chemoautotrophs, & heterotrophs

  • some aerobic, some anaerobic


Proteobacteria1

Proteobacteria


Chlamydias

Chlamydias

  • all parasites

  • Intracellular

  • Gram(-) but lack peptidoglycan in cell wall

  • Chlamydia trachomatis: #1 cause of blindness in the world & causes most common STD in USA


Chlamydia trachomatis

Chlamydia trachomatis


Chlamydia trachomatis1

Chlamydia trachomatis


Spirochetes

Spirochetes

  • helical heterotrophs

  • internal flagellum-like structures that allows them to corkscrew through their environment

  • pathogenic strains:

    • Treponemapallidum: syphilis

    • Borreliaburgdorferi: Lyme disease


Spirochetes1

Spirochetes

SYPHILIS

Lyme disease


Cyanobacteria

Cyanobacteria

  • photoautotrophic

  • likely have common ancestor with chloroplast

  • solitary or filamentous (some filaments have cells specialized for N fixation)

  • component of freshwater or marine phytoplankton


Cyanobacteria1

Cyanobacteria


Gram bacteria

Gram + Bacteria

Actinomyces

Actinomycesodontolyticus

  • fungus-like

  • form branched chains

  • includes TB and leprosy

  • includes many decomposers in soil (earthy odor in soil)


Diversity of gram bacteria

Diversity of Gram + Bacteria


Diversity of gram bacteria1

Diversity of Gram + Bacteria


Diversity of gram bacteria2

Diversity of Gram + Bacteria


Diversity of gram bacteria3

Diversity of Gram + Bacteria


Diversity of gram bacteria4

Diversity of Gram + Bacteria

  • Mycoplasmas only bacteria known to lack cell walls

  • smallest known cells (diameters 0.1 micron)

  • some free-living soil bacteria, some pathogens

  • Mycoplasmapneumoniae


Prokaryotic interactions in biosphere

Prokaryotic Interactions in Biosphere

  • Decomposers

    • recycle nutrients from dead organisms & waste products


Bacteria archaea

2. Autotrophic bacteria convert CO2 

organic cpds; some releasing O2

others (kingdom Crenarchaeota) fix N2 gas  organic cpds


Bacteria archaea

  • Symbiotic Relationships

  • Mutualism

  • Commensalism

  • Parasitism

  • Pathogens


Flashlight fish mutualistic relationship

Flashlight FishMutualistic Relationship


Pathogenic prokaryotes

Pathogenic Prokaryotes

  • usually cause illness by producing:

    • exotoxin

    • endotoxin


Bacteria archaea

exotoxins

endotoxins

lippolysaccharide from outer membrane of gram

(-) bacteria

released when bacteria die

example: Salmonella typhi

  • released by pathogen

  • cause illness even if bacteria no longer present

  • example: Clostridium botulinum


How bacteria can become more virulent

How Bacteria can become more Virulent

  • carry resistant genes

  • horizontal gene transfer

    • harmless bacteria  virulent strains


Horizontal gene transfer

Horizontal Gene Transfer


Example of horizontal gene transfer

Example of Horizontal Gene Transfer

  • E coli strain 0157:H7 has become a global threat: causes severe bloody diarrhea

  • 1,387 genes in this strain not originally from E coli …many are phage genes

    • 1 of those genes codes for an adhesive fimbriae that allow bacteria to attach self to intestinal wall cells & extract nutrients


Prokaryotes in research technology

Prokaryotes in Research & Technology

long history: making cheese, wine, sewage treatment

new biotechnologies:

  • transgenic grains, rice

  • bacteria used in manufacture of plastics  biodegradable

  • ethanol- producing bacteria

  • bioremediation:

    • bacteria that can degrade oil spills


Medical uses of prokaryotes

Medical Uses of Prokaryotes

  • with genetic engineering bacteria can produce:

    • Vitamins

    • Antibiotics

    • Hormones

    • Enzymes


  • Login