MICROBIOLOGY 2117 STUDY EXAMS GUIDE ALL
QUESTIONS AND ANSWERS SURE A+
✔✔What does pleomorphic mean? - ✔✔that an organism can assume many different
shapes
✔✔Name the three components of the cell envelope of a prokaryotic cell: - ✔✔1. cell
membrane 2. cell wall 3. glycocalyx
✔✔Name 4 external structures of the prokaryotic cell: - ✔✔1. glycocalyx 2. flagella 3.
fimbriae 4. pili
✔✔What are pili? - ✔✔short hairlike protein structures on the surface of some bacteria
✔✔What is the purpose of conjugation pili? - ✔✔transfer DNA from one bacteria to
another
✔✔What is the purpose of attachment pili (also called fimbriae)? - ✔✔they are only
used for attachment not movement
✔✔What is meant by the glycocalyx? - ✔✔external to cell wall- keeps cell from drying
out
,✔✔Which organic compounds is the glycocalyx made of? - ✔✔polysaccharides and
peptides
✔✔What is a capsule? What is its purpose? - ✔✔A capsule is part of the glycocalyx
composed of repeating units of organic chemicals and is firmly attached to the cell wall.
It enhances the bacteria's ability to cause disease and protects the bacteria from
dessecation.
✔✔What is a slime layer? What is its purpose? - ✔✔A slime layer is a thin protective
structure loosely bound to the cell wall that protects against drying, helps trap nutrients,
and sometimes binds cells together.
✔✔Are bacterial and eukaryotic flagella constructed the same way? - ✔✔bacterial
flagella are composed of the protein flagellin, which is coiled around into a stiff filament.
Movement of a bacterial cell is generated by rotation of the filament, a bit how like a
propellor works. Reversing direction of rotation can change direction of movement. In
eukaryotic flagella, the structure is more complex. The base of the eukaryotic flagella
houses the foundation of the structure. Nine microtubule groups, each consisting of
three microtubules, form the base of the flagella. Further away from the cell, the flagella
is made up of two microtubule's connected by a bridge. A eukaryotic flagella moves its
cell by sliding adjacent pairs of microtubules, which causes the flagella to bend. This
bending creates movement.
✔✔What are twiddles and runs? - ✔✔The act of bacterial forward movement via
flagellar action is called a run. The spinning of flagella in reverse results in a at first
seemingly maladaptive tumbling, whereby bacteria cells stop moving "forward" and
instead randomly reorient themselves via a literally tumble-like action.
✔✔What is an axial filament? - ✔✔an axial filament wraps around the cell between the
cytoplasmic membrane and the outer membrane. Rotation of the endoflagella causes
the axial filament to rotate around the cell causing a corkscrew movement.
✔✔Which bacteria have axial filaments? - ✔✔spirochete
✔✔Amphitrichous - ✔✔flagella at both ends
✔✔monotrichous - ✔✔single flagellum
✔✔lophotrichouls - ✔✔several flagella protruding from one end
✔✔peritrichous - ✔✔flagella distributed over entire cell
✔✔What is the cell membrane of a prokaryotic cell made of? - ✔✔phopholipids
, ✔✔What is the function of the cell membrane of a prokaryotic cell? - ✔✔controls what
gets in and out of the cell. Nutrients are brought in and wastes are removed.
✔✔What is the cell wall of prokaryotic cells made of? - ✔✔peptidoglycan
✔✔What is the function of the prokaryotic cell wall? - ✔✔shape, protection against
osmotic shock
✔✔What is peptidoglycan? - ✔✔a polymer consisting of sugars and amino acids that
forms a mesh-like layer outside the plasma membrane of bacteria (but not Archaea)
✔✔Where are the sugars of peptidoglycan and what are they? - ✔✔The sugars are the
glycan portion- they are NAG and NAM which alternate to form chains
✔✔Where are the peptides? What do they do? - ✔✔the peptides are the peptido
portion- they connect the sugar chains by peptide bridges.
✔✔What is meant by "thick" peptidoglycan and "thin" peptidoglycan? - ✔✔the
percentage of peptidoglycan in a cell wall. Gram positive cells have 90% peptidoglycan,
and gram negative cells only have around 10-20% peptidoglycan.
✔✔Which bacteria have an LPS layer? - ✔✔gram negative
✔✔What is an LPS layer? - ✔✔a layer of lipopolysaccharide- a combination of lipids
and sugar.
✔✔What is the significance of Lipid A? - ✔✔lipid portion of LPS- dead cells release lipid
A which is toxic to humans in large amounts. It causes an immune response.
✔✔What is an endotoxin? - ✔✔associated with some Gram-negative bacteria. An
"endotoxin" is a toxin that is a structural molecule of the bacteria that is recognized by
the immune system.
✔✔What do endotoxins do in the body when released in large numbers? -
✔✔Endotoxins have been shown to produce fever, a decrease in blood pressure, and
activation of inflammation and coagulation. Endotoxins are in large part responsible for
the dramatic clinical manifestations of infections with pathogenic Gram-negative
bacteria
✔✔Teichoic acid function: - ✔✔some are linked to lipids. Teichoic acids have negative
charges which help give gram positive bacteria a negative charge, thus playing a role in
the passage of ions through the cell wall.
QUESTIONS AND ANSWERS SURE A+
✔✔What does pleomorphic mean? - ✔✔that an organism can assume many different
shapes
✔✔Name the three components of the cell envelope of a prokaryotic cell: - ✔✔1. cell
membrane 2. cell wall 3. glycocalyx
✔✔Name 4 external structures of the prokaryotic cell: - ✔✔1. glycocalyx 2. flagella 3.
fimbriae 4. pili
✔✔What are pili? - ✔✔short hairlike protein structures on the surface of some bacteria
✔✔What is the purpose of conjugation pili? - ✔✔transfer DNA from one bacteria to
another
✔✔What is the purpose of attachment pili (also called fimbriae)? - ✔✔they are only
used for attachment not movement
✔✔What is meant by the glycocalyx? - ✔✔external to cell wall- keeps cell from drying
out
,✔✔Which organic compounds is the glycocalyx made of? - ✔✔polysaccharides and
peptides
✔✔What is a capsule? What is its purpose? - ✔✔A capsule is part of the glycocalyx
composed of repeating units of organic chemicals and is firmly attached to the cell wall.
It enhances the bacteria's ability to cause disease and protects the bacteria from
dessecation.
✔✔What is a slime layer? What is its purpose? - ✔✔A slime layer is a thin protective
structure loosely bound to the cell wall that protects against drying, helps trap nutrients,
and sometimes binds cells together.
✔✔Are bacterial and eukaryotic flagella constructed the same way? - ✔✔bacterial
flagella are composed of the protein flagellin, which is coiled around into a stiff filament.
Movement of a bacterial cell is generated by rotation of the filament, a bit how like a
propellor works. Reversing direction of rotation can change direction of movement. In
eukaryotic flagella, the structure is more complex. The base of the eukaryotic flagella
houses the foundation of the structure. Nine microtubule groups, each consisting of
three microtubules, form the base of the flagella. Further away from the cell, the flagella
is made up of two microtubule's connected by a bridge. A eukaryotic flagella moves its
cell by sliding adjacent pairs of microtubules, which causes the flagella to bend. This
bending creates movement.
✔✔What are twiddles and runs? - ✔✔The act of bacterial forward movement via
flagellar action is called a run. The spinning of flagella in reverse results in a at first
seemingly maladaptive tumbling, whereby bacteria cells stop moving "forward" and
instead randomly reorient themselves via a literally tumble-like action.
✔✔What is an axial filament? - ✔✔an axial filament wraps around the cell between the
cytoplasmic membrane and the outer membrane. Rotation of the endoflagella causes
the axial filament to rotate around the cell causing a corkscrew movement.
✔✔Which bacteria have axial filaments? - ✔✔spirochete
✔✔Amphitrichous - ✔✔flagella at both ends
✔✔monotrichous - ✔✔single flagellum
✔✔lophotrichouls - ✔✔several flagella protruding from one end
✔✔peritrichous - ✔✔flagella distributed over entire cell
✔✔What is the cell membrane of a prokaryotic cell made of? - ✔✔phopholipids
, ✔✔What is the function of the cell membrane of a prokaryotic cell? - ✔✔controls what
gets in and out of the cell. Nutrients are brought in and wastes are removed.
✔✔What is the cell wall of prokaryotic cells made of? - ✔✔peptidoglycan
✔✔What is the function of the prokaryotic cell wall? - ✔✔shape, protection against
osmotic shock
✔✔What is peptidoglycan? - ✔✔a polymer consisting of sugars and amino acids that
forms a mesh-like layer outside the plasma membrane of bacteria (but not Archaea)
✔✔Where are the sugars of peptidoglycan and what are they? - ✔✔The sugars are the
glycan portion- they are NAG and NAM which alternate to form chains
✔✔Where are the peptides? What do they do? - ✔✔the peptides are the peptido
portion- they connect the sugar chains by peptide bridges.
✔✔What is meant by "thick" peptidoglycan and "thin" peptidoglycan? - ✔✔the
percentage of peptidoglycan in a cell wall. Gram positive cells have 90% peptidoglycan,
and gram negative cells only have around 10-20% peptidoglycan.
✔✔Which bacteria have an LPS layer? - ✔✔gram negative
✔✔What is an LPS layer? - ✔✔a layer of lipopolysaccharide- a combination of lipids
and sugar.
✔✔What is the significance of Lipid A? - ✔✔lipid portion of LPS- dead cells release lipid
A which is toxic to humans in large amounts. It causes an immune response.
✔✔What is an endotoxin? - ✔✔associated with some Gram-negative bacteria. An
"endotoxin" is a toxin that is a structural molecule of the bacteria that is recognized by
the immune system.
✔✔What do endotoxins do in the body when released in large numbers? -
✔✔Endotoxins have been shown to produce fever, a decrease in blood pressure, and
activation of inflammation and coagulation. Endotoxins are in large part responsible for
the dramatic clinical manifestations of infections with pathogenic Gram-negative
bacteria
✔✔Teichoic acid function: - ✔✔some are linked to lipids. Teichoic acids have negative
charges which help give gram positive bacteria a negative charge, thus playing a role in
the passage of ions through the cell wall.
