3 Anatomy of a Typical Bacterial (Prokaryotic) Cell Flashcards
Avg size of a bacterium?
2 micron diameter
What is the advantage of having a high surface-to-volume ratio?
Nutrients and wastes can move into and out of the bacterial cell, respectively, quite efficiently
3 main bacterial shapes?
- Bacillus (rod)
- Coccus (round)
- Spirochete (spiral)
How can bacteria be arranged? (4)
- Singles
- Pairs
- Clusters
- Chains
T or F: Bacteria are relatively complex compared to eukaryotic cells.
F
They are, in fact, simpler than eukaryotic cells.
Name the 3 typical structures of a bacterial cell.
- Cytoplasm
- Cell envelope/wall
- “External”/optional structures
T or F: Prokaryotic and eukaryotic ribosomes have the same function since they both have the same structure.
F
The prokaryotic ribosome DOES indeed have the same fn as the eukaryotic ribosome. However, their structures are different.
The cell envelope of Gram _____ bacteria has three layers: An inner plasma membrane, a thin peptidoglycan layer, and an outer plasma membrane.
negative
The cell envelope of Gram _____ bacteria has two layers: An inner plasma membrane and a thick outer peptidoglycan layer.
positive
T or F: The INNER plasma membrane of prokaryotes are basically the same as the plasma membrane of eukaryotes in both structure and function.
F
They ARE similar in general structure, but NOT in function
(they contain “metabolic” proteins [i.e. they’re “active” membranes])
Name the component of prokaryotic cell walls that’s not found in eukaryotic cells.
Peptidoglycan
What is a peptidoglycan monomer composed of?
Two carbohydrates and four amino acids.
How many layers of peptidoglycan does a Gram negative bacteria have?
1-2 layers
How many layers of peptidoglycan does a Gram positive bacteria have?
Multiple
Name an enzyme that can break peptidoglycan apart. In what location does it cleave?
Lysozyme.
It cleaves the bond b/w NAG and NAM
What determines whether a cell is Gram positive or negative?
Thickness of peptidoglycan component of the cell wall
Why do Gram negative cells not remain purple during the Gram staining process?
Because they have fewer layers of peptidoglycan, and so the dye is not as easily trapped.
What colour are Gram positive bacteria after staining?
Purple
What colour are Gram negative bacteria after staining?
Red
Do Gram positive or negative bacteria have an outer cell membrane?
Gram negative
What unique molecule (not found in eukaryotes) is embedded in the outer membrane of a Gram negative bacterium?
Lipopolysaccharide (LPS)
What are the three parts of a LPS?
- O-antigen
- Core polysaccharide
- Lipid A
What is the fn of LPS molecules?
Protect the bacterium. It repels toxic compounds in the envir
The human immune sys recognizes the _____ part of LPS.
O-antigen
This part of the LPS causes shock, inflammation, and fever; hence, LPS is also known as ENDOTOXIN
Lipid A
What is a pyrogenic?
Anything that can induce fever.
What part of a Gram negative bacterium is considered to be a pyrogenic agent?
LPS (its lipid A component, specifically)
Name 2 structural diffs b/w Gram positive and Gram negative bacteria.
- Gram positive bacteria have a much thicker peptidoglycan layer
- Gram negative bacteria have an outer membrane and LPS
Name two bacterial species that deviate from the typical Gram (-) and (+) cell envelope structures.
- Mycobacteria species
2. Mycoplasma species
Name the 3 typical structures of a bacterial cell.
- Cytoplasm
- Cell envelope/wall
- “External”/optional structures
T or F: ALL bacteria have external structures.
F
They’re optional (i.e. not necessarily there)
Name 4 optional structures of bacteria.
- Flagella
- Pili (aka fimbriae) [sing. pilus]
- Capsular polysaccharide (aka capsule)
- Bacterial spores (aka endospores)
What are flagella?
Long, thick filaments that can cause movement due to whip-like or propeller-like movements
T or F: Flagellar bacteria only have ONE flagellum.
F
The number of flagella vary in location and number per cell. It depends on species.
What are pili?
Filaments used to ATTACH bacteria to other cells
What’re the two types of pili?
- Sex pili
2. Common pili
What’re sex pili used for?
Attaching bacteria to other bacteria
What’re common pili used for?
Attaching bacteria to eukaryotic cells & tissues
What structure is necessary for many bacteria to cause disease?
Common pili
What are capsular polysaccharides? (aka “capsules”?)
Viscous, sticky polysaccharide material surrounding the bacterial cell
T or F: Capsular polysaccharide structure is constant across species and strains.
F
The chemical structure of the polysaccharide varies b/w species (and s.times b/w strains too).
What are the two main fns of capsules?
- Protection
2. Attachment
What do we call a community of bacteria attached to a living or non-living surface via capsular polysaccharide?
Biofilm
What are single-species biofilms mostly involved in?
Human infections
Where are multi-species biofilms mostly found?
Natural envirs
Name three areas where biofilms can form, making them medically-relevant problems.
- Biofilms form on human tissues during infection > makes it more difficult to treat
- Biofilms form on implanted medical devices
- Biofilms form on tooth surfaces (i.e. plaque)
T or F: Biofilms can detach and become established elsewhere.
T
Name 4 optional structures of bacteria.
- Flagella
- Pili (aka fimbriae) [sing. pilus]
- Capsular polysaccharide (aka capsule)
- Bacterial spores (aka endospores)
What are endospores?
Dormant, non-growing form of bacteria
What causes endospore conversion?
Environmental stress
Endospore formation is mostly a _____ mechanism
survival
T or F: Spores multiply faster than bacteria.
F
Spores are DORMANT. They don’t multiply.
When do spores become vegetative (“growing state”) again?
When environmental stresses are gone and growth conditions are favourable.
How long can a spore stay dormant before it’s no longer able to revert to a growing, vegetative cell?
AT LEAST several decades (maybe longer)
T or F: Spores are more easily killed by pasteurization, boiling, and some germicides.
F
Spores are NOT killed by these things.
