Biology 102 Chapter 15 & 16 - Single-Celled Life
Three Domains of Life
Domains
1. Bacteria All single-celled prokaryotes
2. Archaea
3. Eukarya Single- and multicellular eukaryotes
Prokaryotes
Bacteria and Archaea
● microscopic
● Simple cells – no membrane-bound
organelles
● DNA in a single loop
Most abundant life forms
● number of species (2/3)
● Number of individuals (5 nonillion)
Very high reproductive rate
● 10-30 minutes
● Plasma membrane, cytoplasm,
ribosomes
● DNA - small genome, no introns
● Cell wall - extra protective layer
● Capsule -helps elude immune systems
● Pili - for sticking to things/each other
● Flagellum - motility
Prokaryotes come in a variety of shapes
Corkscrew Comma Rod Sphere Spiral
(spirochete) (vibrio) (bacillus) (coccus) (spirillum)
1
, Biology 102 Chapter 15 & 16 - Single-Celled Life
Archaea
● Differ from bacteria in a few Archaea found in mineral hot springs are able
significant ways to withstand extreme acidity and high
● Share traits with eukaryotes temperatures.
○ Chromosome structure
● Many are extremophiles A new archaean species was recently found in
○ Thermophiles an abandoned copper mine. Others have been
○ Halophiles found living in acidic drainage from mines.
○ Methanogens
Many bacteria and Archaean species are Hydrogen-eating, methane- producing
anaerobic. archaeans have been found in deep-sea
● Respiration with a different final thermal vents.
electron acceptor
● Fermentation
Metabolism
All living things can be categorized as either:
● Autotrophs: can produce their own ● Heterotrophs: must eat
food ○ Get carbon from organic
○ Get carbon from CO2 matter
○ Photosynthesis in plants ○ Animals, fungi
Prokaryotes can be either
Eukaryotic cells
● DNA enclosed in a membrane-bound nucleus
● Multiple other specialized organelles
● 10 times larger diameter than prokaryotic cells
● 1000 times more volume
Protists do not form a single group, they come from several groups. Defined simply as not being
animals, plants, or fungi.
● Most protists are single-celled.
● Some actually take multicellular form but not as complex as plants and animals.
2
Three Domains of Life
Domains
1. Bacteria All single-celled prokaryotes
2. Archaea
3. Eukarya Single- and multicellular eukaryotes
Prokaryotes
Bacteria and Archaea
● microscopic
● Simple cells – no membrane-bound
organelles
● DNA in a single loop
Most abundant life forms
● number of species (2/3)
● Number of individuals (5 nonillion)
Very high reproductive rate
● 10-30 minutes
● Plasma membrane, cytoplasm,
ribosomes
● DNA - small genome, no introns
● Cell wall - extra protective layer
● Capsule -helps elude immune systems
● Pili - for sticking to things/each other
● Flagellum - motility
Prokaryotes come in a variety of shapes
Corkscrew Comma Rod Sphere Spiral
(spirochete) (vibrio) (bacillus) (coccus) (spirillum)
1
, Biology 102 Chapter 15 & 16 - Single-Celled Life
Archaea
● Differ from bacteria in a few Archaea found in mineral hot springs are able
significant ways to withstand extreme acidity and high
● Share traits with eukaryotes temperatures.
○ Chromosome structure
● Many are extremophiles A new archaean species was recently found in
○ Thermophiles an abandoned copper mine. Others have been
○ Halophiles found living in acidic drainage from mines.
○ Methanogens
Many bacteria and Archaean species are Hydrogen-eating, methane- producing
anaerobic. archaeans have been found in deep-sea
● Respiration with a different final thermal vents.
electron acceptor
● Fermentation
Metabolism
All living things can be categorized as either:
● Autotrophs: can produce their own ● Heterotrophs: must eat
food ○ Get carbon from organic
○ Get carbon from CO2 matter
○ Photosynthesis in plants ○ Animals, fungi
Prokaryotes can be either
Eukaryotic cells
● DNA enclosed in a membrane-bound nucleus
● Multiple other specialized organelles
● 10 times larger diameter than prokaryotic cells
● 1000 times more volume
Protists do not form a single group, they come from several groups. Defined simply as not being
animals, plants, or fungi.
● Most protists are single-celled.
● Some actually take multicellular form but not as complex as plants and animals.
2
