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(1 of 12) Differences Between Prokaryotic and Eukaryotic Organisms

Madigan, et al. (1996) Brock: Biology of Microorganisms Chapter 3

(2 of 12) Microorganisms Are the Lowest Form of Life on Earth

  • Microorganisms can combine plant and animal characteristics

    • photosynthetic organism with flagella

  • Organisms can have apparently similar structures that are really quite different

    • flagella in bacteria versus protozoa

(3 of 12) Characteristics of Prokaryotic and Eukaryotic Microorganisms

 

Prokaryotes

Eukaryotes

Includes:

Bacteria, Archaea

Fungi, Algae, Protozoa

Cell width:

< 2u

2-100u

Cell type:

most unicellular
non septate

most filamentous
have septa

Motility:

flagella
gliding

flagella, cilia
gliding, amoeboid

(4 of 12) Basic Cell Structure in Eukaryotic Organisms

(5 of 12) Eukaryotic Cell Structure: Fungus Mycelium

  • Branched mycelium with transverse cell walls

  • Cell width commonly 20µ

  • Numerous spores

  • Cell wall with chitin or glucan

  • Heterotrophs requiring external carbon source

Medium

(6 of 12) Prokaryotic Cell Structure

(7 of 12) Prokaryotic and Eukaryotic Cells

 

Prokaryotes

Eukaryotes

Cell wall:

Present in most
Mucopeptide, LPS
Polysaccharide
Protein

Present in most
Polysaccharide

Internal
membranes:

Simple,
mainly in autotrophs

Complex
Endoplasmic reticulum, Golgi

Mitochondria:

None

Present

Ribosomes:

70s

80s, except in organelles

Chloroplasts:

None

In phototrophs

(8 of 12) Other Differences Between Prokaryotes and Eukaryotes

 

Prokaryotes

Eukaryotes

Poly-A mRNA:

No

Yes

Plasmids:

Common

Rare

Sulfur reduction:

Common

No

N2 fixation:

Common

No

Autotrophy:

Not uncommon

No

PHB storage:

Common

No

Photosynthesis:

Use H2S, except cyanobacteria

Uses H2O

(9 of 12) Nuclear Structure and Function

 

Prokaryotes

Eukaryotes

Nuclear membrane:

Absent

Present

Nucleolus:

Absent

Present

DNA:

Single
Circular
Plasmids

Various
Chromosomes

Cell division:

No Mitosis

Mitosis

Sexual reproduction:

Rare

Meiosis, Reassortment

Introns:

Rare

Common

(10 of 12) Differences Between Bacteria and Archaea

  • Cell wall of archaea does not contain muramic acid

  • Bacterial membrane lipids ester linked; those of archaea, ether linked

  • RNA polymerase types/structure differs

  • Sensitivity to chloramphenicol, streptomycin and kanamycin in bacteria, not archaea

  • Archaea may be methanogenic or tolerate extreme environments

(11 of 12) Viruses and Prions

  • Viruses are submicroscopic particles which must reproduce in plant, animal, or bacterial cell.

  • Outside the host, viruses comprise single- or double-stranded RNA or DNA, surrounded by a protein capsid, and are metabolically inert.

  • Bacterial viruses infect their specific host and cause its lysis. Temperate phages are known.

  • Bacteriocins and prions are both proteins, with no nucleic acid.

( 12 of 12) Bacteriophage (Bacterial Virus)

  • Obligate parasites of bacteria

  • Each phage has a specific host range usually within a single genus

  • Maintained by progation on their host, produce lytic plaques in agar culture

  • Composed of protein head enclosing DNA and a contractile tail

  • Attach to an appropriate host via the tail, inject DNA into the host, modify host metabolism--->more virus

 

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