Prokaryotes are a biological success story

prokaryote

a single-celled organism that lacks a nucleus and membrane-bounded organelles

1. bacteria and archaea

   1. do not seem related to each other

2. do not form a single clade

3. 10 to 100 times smaller than eukaryotes

bacteria

Earliest known fossils resemble today’s

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archaea

more cloesly related to eukaryotes than bacteria

cell structure and metabolism

Prokaryote classification traditionally relies on what two things?

light and electron microscopes

What reveals internal cell structures?

nucleoid

where DNA is located

1. internal cell structure

2. RNA and some proteins

3. No membranous envellope

4. DNA is one circular chromosome

plasmids

circle of DNA apart from the chromosome

1. internal cell structure

2. genes on it may encode the proteins needed to copy the plasmid and transfer it to another cell

3. other genes may provide the ability to resist an antibiotic/toxin, cause disease, alter the cell’s metabolism

4. Recombinant DNA technology uses this to ferry genes from one kind of cell to another

ribosomes

structures that use the information in RNA to assemble proteins

1. internal cell structure

2. bacteria, archaea and eukaryotes make proteins in esentially the same way

   1. though the structure is different

   2. antibiotic streptomycin kills bacteria without hurting host’s eukaryotes, exploting the structural difference

cell wall

rigid barrier that surrounds the cells of most bacteria and archaea

1. external cell structure

2. for most species of bacteria, this is made with peptidoglycan (archaea do not have this)

3. for archaea, this is made primarily of protein

peptidoglycan

a complex polysaccaride

1. only bacteria can have this at all

   1. it is used for the cell wall

peptidoglucan synthesis

1. penicillin inhibits reproduction of bacteria by interfering with this

   1. archaea are therefore not affected

coccus

spherical shape of a cell wall

bacillus

rod-shaped cell wall

spirllum

spiral or cork-screw shaped cell wall

staphylo-

prefic for cells arranged in pairs, clusters

strepto-

prefix of cells that are arranged in chains