Microscopy and Prokaryotic Cell Morphology
This microscope allows us to view viruses.
Electron microscope.
Which molecule in bacterial membranes functions like cholesterol in eukaryotes, and why is it important?
Hopanoids; they stabilize the membrane, especially under stress conditions.
If you forget to add the primary stain (crystal violet) during a Gram stain, how will Gram positive and Gram negative bacteria appear at the end?
Gram positive = pink, Gram negative = pink (only safranin shows)
This inclusion body stores enzymes that allow for CO2 fixation.
Carboxysomes - organic inclusion body
The name of the process bacteria uses to increase in cell number
Binary Fission
Name the 4 types of light microscopes.
Bright Field, Dark Field, Phase Contrast, and Fluorescence
Which type of bacteria has a thicker peptidoglycan layer, Gram-positive or Gram-negative? Which has a larger periplasmic space?
Gram-positive bacteria have the thicker peptidoglycan layer. Gram-negative bacteria have the larger periplasmic space (between the plasma membrane and outer membrane).
If you forget to perform the wash step (alcohol/acetone) in a Gram stain, how will Gram positive and Gram negative bacteria appear?
Gram positive = purple, Gram negative = purple (no differentiation occurs)
This idea explains why eukaryotes have 70s and 80s ribosomes.
Endosymbiont theory.
This type of bacteria thrives in cold environments (0-20C)
Psychrophiles
List the 5 kingdoms and the 3 domains.
5 kingdoms: Monera, Protista, Fungi, Plantae, Animalia & 3 domains: Bacteria, Archaea, Eukarya
What determines the thickness of peptidoglycan in Gram-negative versus Gram-positive bacteria?
Gram-negative: Thickness is determined by the number of NAG-NAM sheets. Gram-positive: Thickness is determined by the number of NAG-NAM sheets, the number of amino acids in the interbridge, and the size of those amino acids.
If you forget to add the counterstain (safranin) during a Gram stain, how will Gram positive and Gram negative bacteria appear?
Gram positive = purple, Gram negative = colorless (since they lost crystal violet but were never counterstained)
Endospores are heat resistant because of this compound.
Calcium-dipicolinic acid.
This is the phase of the Microbial Growth Curve where the number of living cells is equal to the number of dead cells.
Stationary Phase, this occures because there is decreased nutrients and increased waste.
There are two microbes that are neither prokaryotic or eukaryotic.
Viruses and prions. Viruses are obligate intracellular parasites, and prions are infectious proteins.
How does penicillin work and why is it less effective against Gram– bacteria?
Penicillin blocks the formation of cross-links in peptidoglycan, weakening the cell wall and leading to lysis. It is less effective against Gram– bacteria because their outer membrane acts as a barrier, preventing penicillin from reaching the peptidoglycan layer.
During an acid-fast stain, you forget to apply the decolorizer (acid alcohol). How will acid-fast and non–acid-fast cells appear?
Acid-fast (cells w/ mycolic acid) = pink (correct), non–acid-fast (cells w/o mycolic acid) = pink (they never lost the primary stain, so both look the same)
This term means "sugar shell" and encompasses the capsule and slime layer.
Glycocalyx.
These are the two ways bacteria can aquire drug resistance.
1. Horizontal Gene Transfer
2. Spontaneos, random mutations
There are 4 shapes of bacteria. Explain each.
Coccus (round, spherical)
Bacillus (rods, different length to width ratios)
Vibrios (curved rods, commas)
Spirals (long rods, twisted into corkscrews)
Which type of bacteria release endotoxin, what is endotoxin, which part of LPS is toxic, and what effect does it have on the host?
Gram-negative bacteria release endotoxin, which is the Lipid A portion of lipopolysaccharide (LPS). When released during cell death, it triggers strong immune responses, including fever, inflammation, and septic shock.
If you perform an endospore stain but forget the heat step while applying malachite green, how will endospores and vegetative cells appear?
Endospores = colorless (dye never penetrated), vegetative cells = pink/red (safranin only)
This type of motility is used by spirochetes and uses internal flagella.
Axial filament.
The original number of bacteria when there are 100,000 bacteria after 2 hours and the doubling time is 10 minutes.
Approximately 24