1. First life forms to evolve
2. Unicellular but may form collonies
3. microscopic cells
4. Three body forms
5. Short generation time
6. High rate of mutation
7. higher species diversity than eukaryotes
8. Greater biomass of any organsim
9. can live in extreme environments

0.-5 microns vs. 10-100 microns of a eukaryote

Spherical (cocci)

rod (bacilli)

Spiral

why do prokaryotes have a short generation time?

• gene pool diversification and adaptation
• lack homologous chromosomes= all mutations passed onto next generation

e.g., there is a greater ribosomal RNA gene variation between 2 strains of E. coli than between a human and a platypus!

Path note: E. Coli species is so diverse= hard to keep ahead (medicine) pathogenically

Cellular Structure of prokaryotes

Cell wall Fx

1. provides structure
2. prevents lysis in hypotonic state and crenation in hypertonic state
3. reduces desiccation
4. reduces abrasion (sand wind salt environment
5. reduceschemical diffusion E.g., antibiotics in gram neg spp.

Cellular Structure of prokaryotes

Domain Bacteria cell wall

Cellular Structure of prokaryotes

Gram negative spp. cell wall

Complex cell wall

Likes anerobic environment

1. helps protect bacteria from immune response in humans
2. resists many antibiotics
3. w/ lipopolysaccaride membrane that may be toxic causing fever/ shock (e.g., Tampons toxic shock syndrome (TSS)

Note:Pennicillin inhibits formation of peptidoglycan making the cell wall non- functional (doesn't kill, just prevents  reproduction)

***** Cellular Structure of prokaryotes

Domain Archaea Cell wall

Composed of polysaccharides and protein but with out polypeptidoglycan

this is different than that of bacteria

Note: it is this difference in cell wall chemistry tht is one of the promary characteristics that seperates the two domains

Cellular Structure of prokaryotes

Capsules

Many prokaryotes have cell walls covered with capsules made of sticky protein or polysaccharide

e.g., not brushing teeth, wash your toothbrush

Cellular Structure of prokaryotes

Fx of capsuels

1. stick to surface
2. form colonies
3. resist attack by immune responses
4. reduce deseccation

Cellular Structure of prokaryotes

Finbriae

Cellular Structure of prokaryotes

fx of fimbriae

Attachment

e.g., Neisseria gonorrheae attaches to mucouse membrane in the ureathra with fimbriae

Cellular Structure of prokaryotes

Sex pili(us)

Long hair-like  retractable extensions from cell wall

most in gram negative bacteria

not archaea

Cellular Structure of prokaryotes

fx pili(us)

pulls together prior to plasmid transfer.  Turns into the conjugation bridge.

[image]

Cellular structure of Prokaryotes

Flagella

Motile appendages used for propulsion..occur in any number and any location on cell

Fx: allow taxis (movement in response to stimulous)...movement may be positive or negative.  E.g., positive phototaxis= moving toward light

Cellular structure of Prokaryotes

Lack organelles

no organelles, however, some prokaryotes have membrane folds that perfome specialized functions

ex.

1. Respiratory folds takes place of mitochondria =energy

2.Thylakoid membranes replace ribosomes for protein synthesis

Cellular structure of Prokaryotes

Lack nucleus

Genome is located in a region called a nucleoid...no membrane

(oid means look like)

this is natures first attempt to produce functional cells.

Cellular structure of Prokaryotes

Genetic material

Prokaryotes lack true chromosomes

has Histone proteins that gift wrap ?(not in backteria /archaea)

Contains single circular DNA "chromosomes" with limited proteins as in eukaryotes

Usually contains plasmids, smaller rings of self-replication DNA. Carry accessory genes not found in "chromosomes" e.g, genes for sex pili, or genes for antibiotic resistance (known as the R plasmids)

Cellular structure of Prokaryotes

Endospores

1. The cell replicates its "chromosomes"
2. encapsilates it ina an endospore
3. the remainder of the cell degenerates and water is excluded from the endospore and metabolisme stops

endospores can last centuries in favorable environments.  can survie boiling water.  killed in autoclave at 121°C

Reproduction of Prokaryotes

Prokaryotes recombine their genome by a variety of asexual methods

some species can fission in as little as 20 min (E.coli) under ideal conditions although most take 1-24 hrs.

Rapid reproduction

and mutations (base insertion, deletion, and substitution account for most all variation.)

Genetic Recombination and Reproduction

Binary fission

Non-mitotic replication of the "chromosomes" and subsequent division into two daughter cells

[image]

Genetic Recombination and Reproduction

Transformation

The uptake of foreign DNA from environments, results in a change in genotype (DNA) and possible phenotype (appearence).

Note:

A non-pathogenic strain can pick of the pathogenic gene from ruptured cells in its environment!  This is accomplished through special cell wall proteins that recognize DNA from related species & transport it into the cell.

Genetic Recombination and Reproduction

Transduction

Bacteriophages carry bacterial genes from one host to another during phage reproduction

Virus not capable of reproduction on own

Genetic Recombination and Reproduction

Conjugation

Genetic Recombination and Reproduction

Conjugation

note from example

F plasmid and F chromosome pieces also contatin many genes not associated with formation of the pilus...modifies the genome of the recipient.  Like a happy meal with an extra toy.

these plasmids may contain up to several hundred genes.

transfers via  HFr cell ( high frequency recombination) F factor integrates into the bacterial chromosome.

know figure 27.13

R plasmids may also be transferred by plasmid transfer and confer resistance to antibiotics.

Require inorganic source of carbon eg. CO2-carbon dioxide

plants, algea

Require organic source of carbon eg. glucose

humans, animals

energy obtained from light

plants, blue green bacteria

Chemotrohic(trophs)

Photoautotroph-light energy-CO2 carbon

chemoautotroph- inorganic chemicals energy- CO2 carbon

Photoheterotroph- light energy- organinc componds carbon

Chemoheterotroph- organic compounds for energy- organic compounds for carbon...glucose+ chemicals=humans

know table 27.1

oxygen not used in ATP synthesis (only glycolysis net 2 ATP)

bogs swamps etc... these types of organisms are typically poisoned by oxygen

Oxygen is toxic

eg. Clostridium botulinum-dented can goods

botulism, botox...

     Use either fermentation or use nitrate (NO₃^-)or sulfate (SO₄^2-)to accept  
     electrons instead of O2 in the electron transport chain.