Microbiology with Disease by Body
System Chapter 11-Characterizing
and Classifying Prokaryotes
3 basic shapes:
1. Cocci (spherical)
2. Bacilli (rod-shaped)
3. Spirals (stiff=spirilla, flexible=spirochetes
3 variations:
1. Vibrios (slightly curved rods)
2. Coccobacilli (in between cocci and bacilli)
3. Pleomorphic (variable shape and size) - 3 basic prok shapes, 3 shape varations
Environmentally resistant endospores are produced within vegetative cells of the Gram-positive genera
Bacillus and Clostridium. Depending on the species in which they are formed,
the endospores may be terminal (at the end), subterminal (near the end), or centrally located. -
Endospores
1. Binary fission
2. Snapping division
3. Spore formation
4. Budding - 4 types of asexual repro in proks
Most common form of bacterial reproduction.
1. DNA replication, each molecule attaches to cytoplasmic membrane
2. Cell grows, moving daughter DNA molecules apart.
3. Cross wall forms (is like an inner cell wall), membrane invaginates, completely dividing cells.
4. Daughter cells may or may not separate.
Parental cell now does not exist. - Binary Fission
Occurs in some Gram-positive bacilli
A variation of binary fission. Only the inner portion of a cell wall is deposited across dividing cell (not the
original cell wall). Cross wall thickening puts tension on outer layer of old cell wall, eventually breaking.
Daughter cells then can remain hanging together almost on a hinge.
Parental cell now does not exist. - Snapping division
, Parental cell retains identity. Actinomycetes does this.
Reproductive cells called spores formed at the end of parental cells (cells grow in filament chains). Each
spore can develop into a clone of parent cell. - Spore formation
Cell outgrowth (bud) receives a copy of the genetic material and enlarges, cutting off from parent cell. -
Budding
Arragement stems from two aspects of binary fission: the planes in which cells divide and whether or
not daughter cells remain attached. - How do bacterial arrangements come about?
Cocci found in groups:
1. streptococci=long chains
2. diplococci=pairs
3. tetrads=foursomes (divide in two planes)
4. sarcinae=cuboidal packets (divide in three planes)
5. staphylococci=clusters (divide in random planes) - Cocci arrangements
Bacilli divide across their long axis, are found in:
1. singly,
2. in pairs,
3. in chains
4. palisade: V-shape arrangement, from snapping division - Bacilli arrangements
Prokaryotes taxa recognized on basis of RNA, DNA, protein sequence similarities--generally rRNA
sequences for modren classification schemes.
99.5% of proks have never been isolated and are only known from their rRNA sequences
Bergey's Manual of Systematic Bacteriology classifies proks into:
26 phyla (2 in archae and 24 in bacteria) - Prokaryotic Classification
Low G+C content is below 50%
High G+C content is above 50%
There are similar sequences in rRNA for each category.
Each category in distinct phyla - Low G+C Gram+ vs High G+C Gram+ bacteria
Phylum: Firmicutes:
Classes:
a. Clostridia
b. Mollicutes
c. Bacilli - Low G+C Content gram positive bacteria
Include genera Epulopiscium (giant, diarrhea) , Selenomonas (dental carries), and Clostridium
System Chapter 11-Characterizing
and Classifying Prokaryotes
3 basic shapes:
1. Cocci (spherical)
2. Bacilli (rod-shaped)
3. Spirals (stiff=spirilla, flexible=spirochetes
3 variations:
1. Vibrios (slightly curved rods)
2. Coccobacilli (in between cocci and bacilli)
3. Pleomorphic (variable shape and size) - 3 basic prok shapes, 3 shape varations
Environmentally resistant endospores are produced within vegetative cells of the Gram-positive genera
Bacillus and Clostridium. Depending on the species in which they are formed,
the endospores may be terminal (at the end), subterminal (near the end), or centrally located. -
Endospores
1. Binary fission
2. Snapping division
3. Spore formation
4. Budding - 4 types of asexual repro in proks
Most common form of bacterial reproduction.
1. DNA replication, each molecule attaches to cytoplasmic membrane
2. Cell grows, moving daughter DNA molecules apart.
3. Cross wall forms (is like an inner cell wall), membrane invaginates, completely dividing cells.
4. Daughter cells may or may not separate.
Parental cell now does not exist. - Binary Fission
Occurs in some Gram-positive bacilli
A variation of binary fission. Only the inner portion of a cell wall is deposited across dividing cell (not the
original cell wall). Cross wall thickening puts tension on outer layer of old cell wall, eventually breaking.
Daughter cells then can remain hanging together almost on a hinge.
Parental cell now does not exist. - Snapping division
, Parental cell retains identity. Actinomycetes does this.
Reproductive cells called spores formed at the end of parental cells (cells grow in filament chains). Each
spore can develop into a clone of parent cell. - Spore formation
Cell outgrowth (bud) receives a copy of the genetic material and enlarges, cutting off from parent cell. -
Budding
Arragement stems from two aspects of binary fission: the planes in which cells divide and whether or
not daughter cells remain attached. - How do bacterial arrangements come about?
Cocci found in groups:
1. streptococci=long chains
2. diplococci=pairs
3. tetrads=foursomes (divide in two planes)
4. sarcinae=cuboidal packets (divide in three planes)
5. staphylococci=clusters (divide in random planes) - Cocci arrangements
Bacilli divide across their long axis, are found in:
1. singly,
2. in pairs,
3. in chains
4. palisade: V-shape arrangement, from snapping division - Bacilli arrangements
Prokaryotes taxa recognized on basis of RNA, DNA, protein sequence similarities--generally rRNA
sequences for modren classification schemes.
99.5% of proks have never been isolated and are only known from their rRNA sequences
Bergey's Manual of Systematic Bacteriology classifies proks into:
26 phyla (2 in archae and 24 in bacteria) - Prokaryotic Classification
Low G+C content is below 50%
High G+C content is above 50%
There are similar sequences in rRNA for each category.
Each category in distinct phyla - Low G+C Gram+ vs High G+C Gram+ bacteria
Phylum: Firmicutes:
Classes:
a. Clostridia
b. Mollicutes
c. Bacilli - Low G+C Content gram positive bacteria
Include genera Epulopiscium (giant, diarrhea) , Selenomonas (dental carries), and Clostridium
