True or false:
In general, bacterial cells are larger than human cells
False
True or false:
Bacteria are only visible when using an electron microscope
False
What is the term used to describe a cluster of spherical bacteria?
Staphylococci
What general type of staining is used to separate various types of bacteria based on their cellular structures?
Differential
Why must fresh cells be used for the Gram stain?
As cells age, they may not stain correctly
If you viewed the slide microscopically after the crystal violet step, Gram-positive cells would appear ______ in color while Gram-negative cells would appear ______ in color.
Purple; purple
Why is Gram's iodine added to the slide?
It forms complexes with the crystal violet, decreasing its solubility
If you viewed the slide microscopically after the ethanol/acetone step, Gram-positive cells would appear ______, while Gram-negative cells would appear ______.
Purple; colorless
Gram-positive bacteria retain the crystal violet-iodine complexes because the ethanol/acetone
shrinks the thick peptidoglycan cell wall, making it impermeable
During the Gram stain procedure, bacteria can first be differentiated from each other after the application of ______.
Ethanol or acetone
If the Gram's iodine step was skipped in this technique, what would likely be seen under the microscope, providing all other steps were performed correctly?
Most cells would appear red/pink
True or false:
All bacteria can be classified as either Gram-positive or Gram-negative.
False
True or false:
The presence of flagella can be determined by a Gram stain.
False
Rod-shaped bacteria can be?
Either Gram-positive or Gram-negative
After Gram's iodine is added to the slide, what color do cells appear?
All cells appear purple in color
True or false:
The thinner peptidoglycan layer of Gram-positive bacteria allows the crystal violet-iodine complex to leave the cell.
False
Which of the following cell arrangements is described CORRECTLY?
A. Diplobacillus - pairs of spherical cells
B. Staphylococcus - chains of spherical cells
C. Streptococcus - grape-like clusters of spherical cells
D. Streptobacillus - grape-like clusters o
E
True or false:
Mycoplasma pneumoniae lacks a cell wall and has a pleomorphic morphology.
True
Which of the following bacterial groups is described CORRECTLY?
A. Spirochetes - move by axial fibrils.
B. Actinomycetes - reproduce by fragmentation.
C. Nocardiae - form specialized dispersal cells on aerial mycelia.
D. Spirochetes - move by axial fibril
A
Which of the following bacterial genera is NOT described correctly?
A. Clostridium - spore-forming rod
B. Corynebacterium - spherical
C. Vibrio - curved rod
D. Clostridium - spore-forming rod and
Vibrio - curved rod
E. Clostridium - spore-forming rod and
B
Which of the following can affect the resolution of a bright-field microscope?
A. Wavelength of light
B. Type of specimen
C. Quality of lenses
D. Magnification
E. Type of specimen AND magnification
A, B, C
Contrast
Ability to distinguish between an object and its surroundings
Resolution
Ability to distinguish between two points or objects that are very close to one another
Which differential staining method is most important in the diagnosis of tuberculosis?
A. Endospore staining
B. Gram stain
C. Flagella stain
D. Acid-fast stain
D
Which of the following dyes is used first in an acid-fast stain?
A. Methylene blue
B. Safranin
C. Carbol fuchsin
D. Crystal violet
E. Malachite green
C
In the Gram-positive bacterial cell wall, the polymers of NAM and NAG sugars in peptidoglycan are cross-linked together by tetrapeptide chains and ______.
Peptide interbridges
Component of the outer membrane in Gram-negative bacteria that, in large amounts, can induce a lethal immunological response?
Lipopolysaccharide
True or false:
Small amounts of LPS alert the body to invasion by Gram-negative bacteria, while large amounts of LPS may cause shock and death.
True
Lipid A
- Anchors LPS in outer membrane
- Alerts immune system to Gram-negative bacteria
- Composed mostly of fatty acids
- Causes endotoxic effects
O Antigen
- Composed of polysaccharides
- Used to identify bacterial strains
- Outermost part of LPS
The target of penicillin in bacterial cells is ______.
The cell wall
The target of lysozyme in bacterial cells is the ______.
The cell wall
Capsule
- Distinct edges
- Gelatinous (fairly solid)
Slime layer
- Irregular edges
- Diffuse (less solid)
If you remove the glycocalyx of a bacterium, the organism would no longer be able to
Attach to surfaces
Sex pilus
Responsible for transferring DNA from one bacterial cell to another
Flagellum
Responsible for locomotion
FImbriae
Responsible for bacterial attachment to surfaces
Cytoskeleton
Involved in cell division and controlling cell shape
Ribosome
Involved in protein synthesis
Chromosome
Contains genetic information required for survival
Gas vesicle
Contains compounds that aid in buoyancy
Endospore
A dormant cell state
Storage granules
Contains high-molecular weight polymers
Plasmid
Typically contains genetic information that is not required by the cell
Triggers sporulation for bacteria
Nutrient depletion
During phagocytosis, cellular membrane projections will "wrap around" a target. What are these cellular projections called?
Pseudopods
Chloroplast
Location for the cellular process of photosynthesis.
Lysosomes
Location for storage of many types of degradative enzymes.
Golgi Apparatus
Location for protein modification prior to secretion or delivery to other cellular compartments.
Peroxisomes
Location for storage of protective compounds that break down lipids and detoxify certain chemicals.
Nucleus
Location for DNA, and for RNA synthesis.
Endoplasmic Reticulum
Location for protein synthesis and some protein modifications.
Mitochondria
Location for most metabolic reactions in cellular respiration.
A eukaryotic cell that is involved in synthesizing large amounts of protein might be expected to have
- Many ribosomes
- Many chloroplasts
- A lot of smooth ER
Found exclusively in eukaryotic cells
- Lysosomes
- Golgi Apparatus
- Mitochondria
- Endoplasmic Reticulum
Found exclusively in prokaryotic cells
- Endospore
Gram positive
- Purple
- Lots of peptidoglycan
Gram negative
- Pink
- Not much peptidoglycan
- Protective outer membrane
Prokaryotic cells
- Small
- Simple
- Unicellular
- No true nucleus
- One circular chromosome
- No membrane enclosed organelles
- 70S ribosomes
Eukaryotic cells
- True nucleus
- Larger
- Complex
- Unicellular OR multicellular
- Many linear chromosomes
- Contains membrane enclosed organelles
- 80S ribosomes
Coccus
A spherical bacterium
Rod/Bacillus
Cylindrical shape bacterium
Vibrio
Curved rod/Comma shape bacterium
Spirillum
A spiral-shaped bacterium
Spirochete
A spiral-shaped bacterium
Most prokaryotic/bacteria divide by?
Binary fission
Cell envelope
Everything that surrounds the inner cell cytosol
Cytoplasmic membrane
A semipermeable barrier that separates the cell interior (cytoplasm) from the environment
True or false:
All cells have a cell membrane
True
Cell wall
- Made up of peptidoglycan
- Peptides and sugar
Gram positive cell wall
- Many layers of peptidoglycan
- Teichoic acid
Gram negative cell wall
- Thin peptidoglycan layer
- Outer and inner membrane
- Space between membranes contains a thin peptidoglycan cell wall
- Outer membrane contains lipopolysaccharides & porin proteins