Ch 1
Which of the following are eukaryotic microbes?
A) Bacteria
B) Archaea
C) Fungi
D) Protozoa
C & D.) Fungi and Protozoa
Purpose of adhesions in microbes
to attach to host cells
What is the total magnification if the ocular lens is 10× and the objective is 40×?
total magnification = 400x
Name one key structural difference between Gram-positive and Gram-negative bacteria.
Gram-positive = thick peptidoglycan, teichoic acids
Gram-negative = thin peptidoglycan + outer membrane with LPS
What type of cell division do bacteria use?
Binary fission
The theory that Louis Pasteur disproved with his swan-neck flask experiment
Spontaneous generation, which was the idea that living organisms can arise from non-living matter.
Name the 7 F’s of transmission.
Fingers, Flies, Food, Fluids, Fomites, Feces, Fornication
In Gram staining, why do Gram-positive cells remain purple while Gram-negative do not?
Gram-positive have thick peptidoglycan that retains the crystal violet stain ; Gram-negative have thin walls that lose it during decolorization
What is the function of pili in bacteria?
Attachment and DNA transfer (conjugation)
Blood agar is an example of what type of media?
complex media
The reason why viruses are considered noncellular
they cannot reproduce on their own
The difference between facultative anaerobes and aerotolerant anaerobes
facultative: prefers oxygen but can survive without it
aerotolerant: cannot use oxygen at all but can tolerate its presence.
Which type of microscopy relies on the scattering of light?
Darkfield microscopy
When Gram-negative bacteria lyse, this component of their outer membrane triggers a massive immune response, potentially causing fever, inflammation, and septic shock.
lipid A
A psychrophile that can grow in refrigerated food.
Listeria monocytogenes
Name 2 reasons why microbes are essential for life on Earth.
fix nitrogen into forms used by plants, produce vitamins humans consume, serve as primary producers in food webs, decompose organic matter
A graph shows two strains of bacteria: Strain A LD₅₀ = 10³, Strain B LD₅₀ = 10⁶. Which is more virulent and why?
Strain A, because a lower LD₅₀ means fewer organisms are needed to cause disease
Why doesn’t penicillin work against Mycoplasma?
Mycoplasma lack a cell wall, so penicillin (which targets peptidoglycan) is ineffective
Compare swimming and swarming motility in flagella
Swimming = flagella in liquid
Swarming = flagella in semi-solid/jelly surfaces
Culture A starts with 500 cells and doubles every 30 minutes. Culture B starts with 2,000 cells and doubles every 1 hour. After 3 hours, which culture has more cells, and how many does each have?
Culture A has more cells. It has 32,000 while culture B has 16,000.
Name a limitation of Koch's postulates
Certain pathogens only cause symptoms during some cases of infection (latent infections; ex. HIV)
Some pathogens only infect humans
There are pathogens which have progressive infections that are difficult to detect early
Name the stages of an acute infectious disease in order
incubation, prodromal, illness, decline, convalescence, long term
Put the 4 Gram stain steps in order and name the agents
Crystal violet (primary stain) → Iodine (mordant) → ethanol (decolorized) → Safranin (counterstain)
The sizes of prokaryotic ribosomal subunits compared to eukaryotic ribosomal subunits.
30S and 50S (70s) for prokaryotes
40S and 60S (80s) for eukaryotes
How does Helicobacter pylori survive in the acidic stomach if it is not an acidophile?
It produces urease, which breaks down urea to ammonia, neutralizing stomach acid around the bacterium