Infection & Immunity - Mock Quiz 1

In Dr. Else's notes, she lists the morphologies as "Rods, cocci, spherical (spirillum)." (slide 8 on bacteria structure lecture)

I'm not sure why (spirillum) is next to spherical.

I believe cocci are supposed to be sphere shaped and spirillum should be spiral shaped and on its own category. Rod shaped bacteria can be considered baccilus.

The above is considered true due to viruses requiring a host cell in order to replicate.

Lipopolysaccharides (LPS) can produce a condition known as Disseminated Intravascular Coagulation (DIC). LPS is a component of the outer membrane of Gram-negative bacteria and is released during bacterial infection. When LPS enters the bloodstream, it triggers an excessive immune response, leading to the activation of blood clotting factors and the formation of blood clots throughout the body. This widespread clotting can block blood vessels and disrupt normal blood flow, leading to organ damage and the development of DIC. Teichoic acid, on the other hand, is a component of the cell wall of Gram-positive bacteria and is not associated with DIC.

Animalia is not considered a typical component of the 3 domains because the three domains of life are Bacteria, Archaea, and Eukarya. Animalia belongs to the Eukarya domain, which includes all organisms with eukaryotic cells, while Bacteria and Archaea are both domains that consist of prokaryotic organisms. Therefore, Animalia is not considered a typical component of the 3 domains.

The presence of endospores in the liquid would explain your friend's sickness. Endospores are a type of dormant structure formed by some bacteria as a defense mechanism against harsh conditions. They are highly resistant to heat, chemicals, and other environmental stresses, which allows them to survive boiling temperatures. Therefore, even if your friend boiled the water for a prolonged period of time, any bacteria present in the liquid could have formed endospores and survived. When ingested, these endospores can germinate and cause illness, leading to your friend's stomach ache.

Note: Not sure if this is high yield for future exams, but in the lecture these were in red letters. Peptidoglycan is composed of NAM & NAG, n-acetyl muramic acid and n-acetylglucosamine, respectively.

Becareful with this question. Even though bacterial ribosomes consist of a 30S and 50S subunit, they do not add to be 30+50 = 80.

Note that 80S is the sedimentation unit for Eukaryotic ribosomes.

Amoeba, being single-celled organisms that belong to the genus protozoa, fall under the domain Eukarya. This domain includes all organisms with eukaryotic cells, which have a nucleus enclosed within a membrane. Bacteria and Archaea, on the other hand, belong to the domains Bacteria and Archaea, respectively, as they have prokaryotic cells lacking a nucleus.

Don't forget that Prokaryotes have a different set of ribosomes than Eukaryotes! You can differentiate the two by their sedimentation factors, denoted by 70S versus 80S. Do you know which one belongs to prokaryotes and which one belongs to eukaryotes?

A pilus is not considered a part of a flagella. Flagella are long protein structures used by bacteria for motility. The filament is the long, whip-like part of the flagella that extends outward from the cell. The hook is a curved region that connects the filament to the basal body, which is the motor that drives the rotation of the flagella. However, a pilus is a different structure found in bacteria that is involved in processes such as attachment to surfaces or transfer of genetic material. Therefore, the correct answer is "Pillus".

Choice 1 is incorrect because both are considered infectious agents.

Choice 2 is incorrect because it is hard to quantify what is a more "severe" disease. Viruses can cause severe diseases such as Human Immunodeficiency Virus.

If you chose choice 3, remember that viruses have a protein coat surrounding their nucleic acid!

A biofilm is a gel-like layer that allows the adherence of other microorganisms onto it to form a community. This community can consist of various types of microorganisms, such as bacteria, fungi, and algae. The biofilm provides protection and support for the microorganisms, allowing them to thrive and survive in different environments. It also enables the microorganisms within the biofilm to communicate and coordinate their activities, making them more resistant to antibiotics and immune responses.

Teichoic acid is found on gram (+) cell walls

LPS is a component of gram (-) cell walls and is specifically located on the outer lipid cell membrane. LPS has inherent toxic activity and is considered an endotoxin.

Steps 1 and 2 apply the primary stain which colors all of the bacterium purple.

Step 3 is the key step in the gram stain because the application of alcohol is the phase where gram negative cells become colorless (decolorizer phase).

Step 4 is the counter stain phase which colors all of the colorless cells into a reddish/pinkish hue.

If step 3 was not performed, all of the cells would remain purple regardless of the application of a counter stain, making differentiation between gram positives and gram negatives difficult and impractical.

Keep in mind that prokaryotes do not typically have mitochondria.

Gram (+) cells have a single, thick peptidoglycan layer in addition to a single cytoplasmic membrane

Gram (-) cells have an OUTER lipid bilayer and a cytoplasmic lipid bilayer, and sandwiched in-between these two layers is a single thin peptidoglycan cell wall. The space between the two lipid bilayers is called the periplasmic space and is filled with a gel-like fluid called periplasm.

The inner lipid bilayer is referred to as the cytoplasmic membrane and is the correct location for the electron transport chain in gram (-) prokaryotes.

By now you should be able to rule out choice E for prokaryotes :)