Prokaryotes: Kingdoms Archaebacteria and Eubacteria

Chapter 18

Daily Objective

• Investigate Prokaryotes and their two Domains: Domain Archaea and Domain Bacteria

• Bacteria are the most numerous organisms on Earth• Earliest life forms • Contain no nucleus or membrane bound organelles• Most are unicellular

FAST FACTS

• Prokaryotes are divided into 2 domains.• Domain Archaea and Domain Bacteria• ReviewDomain Archaea live in extreme enviornments . They have been found to have similarites with eukaryotic cells. i.e. the ribosomal proteins

Domain Bacteria live in nearly every environment on Earth. Their cell walls contain peptidoglycan.

Daily Objective

• Review Characteristics of Prokaryotes

Domain Archaebacteria

• “ancient bacteria”• Cell walls without peptidoglycan• Subdivided into 3 groups based on their

habitat– methanogens, thermoacidophiles, & extreme halophiles

Domain Bacteria

• “true bacteria”• Most bacteria in this kingdom• Come in 3 basic shapes cocci (spheres), bacilli

(rod-shaped), spirilla (corkscrew shape)• Most are heterotrophic• Can be aerobic, or anerobic

Gram Staining

• Developed in 1884 by microbiologist Hans Gram

• Bacteria are stained purple with dye and iodine, rinsed with alcohol to decolorize, then restained with dye.

• Bacterial cell walls either stain purple or reddish-pink

Gram +/-

Gram (+) Bacteria• Stain purple• Thick layer of peptidoglycan

(protein sugar complex in cell walls)

• Examples: streptoccous, staphylocci

• Can be treated with penicillin (antibiotics)

Gram (-) Bacteria• Stain reddish-pink• Thin layer of peptidoglycan • Antibiotic resistant • Examples; Rhizobacteria,

Rickettsia (Lyme disease)

Prokaryote Structure

Prokaryote Characteristics

• Bacteria can be identified by their shape, cell wall, and movement.

• Shape

Prokaryote Characteristics- cell walls

All bacterial cells have peptidoglycan (sugar and protein) in their cell walls

-can identify bacteria by gram staining.• Bacteria with a large amount of peptidoglycan

appear dark purple (gram +)• Bacteria with a lipid layer has less

peptidoglycan, and will stain reddish pink (gram-)

Reproduction of Prokaryotes

• Most bacteria reproduce asexually by binary fission- chromosome replicates then the cell divides

• Bacteria can sexually reproduce by conjugation- two bacteria from a conjugation bridge or tube between them.

Which method of Reproduction?

Metabolism of Prokaryotes

• Prokaryotes can obtain their energy in multiple ways

Heterotrophs PhotoAutrophs Chemoautotrophs

Do not synthesize own food. Obtain energy by decomposing organic molecules.

Photosynthetic. Release oxygen into the atmosphere

Do not require light for energy. They break down and release inorganic compounds.