BIMM 120_Midterm #2 Practice Question_Saier Milton

True or False: When Tar bacteria are exposed to energy they become unmethylated.

Answer: False b/c methylated/high energy = cold sensor; unmethylated/low energy = warm sensor

True or False: Bacterial Nanowires are type IV pili that have the ability to conduct electrons through aromatic amino acids.

Answer: True

True or False: Thermotaxis is movement based upon the chemical gradient in an environment.

Answer: False b/c based on temperature not chemical gradient

True or False: In lysogenic phage infections, the phage genome integrates into the host genome and is replicated during host cell division without immediately killing the cell.

Answer: True

What is true about the following thermotactic sensors?

Tar is only a cold sensor

Trg is only a cold sensor

Tar is both a warm and cold sensor

Tap is both a warm and cold sensor

Answer: Tar is both a warm and cold sensor

What rotational movement correctly corresponds to the thermotactic (thermotaxis) stimulus?

When Tsr encounters warmth, it will continue to swim smoothly

When Trg encounters cold, it will continue to swim smoothly

When Tap encounters warmth, it will continue to swim smoothly

When Tar encounters warmth, it will become methylated, and it will continue to move into warm environments

Answer: When Tsr encounters warmth, it will continue to swim smoothly

What is directly sensed by MCPs in aerotaxis?

Concentration of O₂ in the environment

Concentration of FAD in the cell

Concentration H+ in the cell

B and C

All of the above

Answer: B and C

Which of the following is a correct description of the behavior of an obligate anaerobe in liquid media?

It will swim up towards the liquid-air interface

It will swim deeper down, away from the liquid-air interface

It will form a sharp band around a specific, preferred O2 concentration

It will be equally distributed at all depths

Answer: It will swim deeper down, away from the liquid-air interface

Why are bacterial nanowires especially useful in environments containing insoluble electron acceptors?

They convert extracellular metals into ATP directly

They allow electron transfer to insoluble compounds outside the cell, making them soluble

They transport metals into the cytoplasm for respiration

They increase membrane permeability to electron acceptors

Answer: They allow electron transfer to insoluble compounds outside the cell, making them soluble

True or False: Conjugation is a way that bacteria can exchange genetic material through a pilus.

Answer: True

True or False: Antibiotics can disrupt the gut microbiome, leading to an overgrowth of harmful bacteria.

Answer: True

True or False: Adhesins allow for entry into the cytoplasm of the cell, allowing virulence factors to enter the host cell.

Answer: False b/c adhesin helps bacteria attach while invasins help bacteria enter host cells

True or False: Bacteria can alter the size of their pores to decrease antibiotic uptake into their cells

Answer: True

When bacteria die at a very slow rate in the presence of antibiotics, this is..?

Persistence

Resistance

Tolerance

Sufferance

Answer: Tolerance

What is true about the concept of horizontal gene transfer? 

Conjugation is the process in which bacteria uptake genetic material from their environment

Transformation is the process in which bacteria get other genetic material through bacteriophages

Translation is the process in which bacteria make new proteins

Transduction is the process in which bacteria get other genetic material through bacteriophages.

Answer: Transduction is the process in which bacteria get other genetic material through bacteriophages.

What is the importance of bacterial capsules? 

They are not important for avoiding the immune system, as the antibodies get stuck in the sticky capsule

They are important in avoiding the immune system, as antibodies will have a hard time binding to the bacteria for immune activation

They are not useful for the binding of surfaces, as they can form biofilms without the capsule

None of the above

Answer: They are important in avoiding the immune system, as antibodies will have a hard time binding to the bacteria for immune activation

Which of the following is not a mechanism of bacteria gaining antimicrobial resistance?  

Bacteria bypass the inhibited pathway and finds an alternative metabolic pathway, thereby making the drug target irrelevant

Bacteria can create enzymes, such as beta-lactamases, that neutralize the antibiotic

The drug randomly mutates and no longer attacks or inhibits the drug target

Transmembrane proteins pump antibiotics out, which expels antimicrobial drugs

Answer: The drug randomly mutates and no longer attacks or inhibits the drug target

Which of the following correctly orders the stages of biofilm formation?

1. Microcolony formation

2. Dispersal

3. Reversible Attachment

4. Irreversible Attachment

3 -> 4 -> 1 -> 2

4 -> 3 -> 1 -> 2

1 -> 3 -> 4 -> 2

2 -> 4 -> 3 -> 1

Answer: 3 -> 4 -> 1 -> 2

Which of the following bacterial protein complexes hydrolyze RNA into individual nucleotides?

Proteasomes

Degradosomes

Carboxysomes

Exosomes

Answer: Degradosomes

Extra Credit: Which of the following does not contribute to the mechanism of the cyanobacteria circadian clock?

KaiA senses light during the day, stimulating KaiC and promoting autophosphorylation

KaiA senses light during the day, stimulating KaiB and facilitates KaiB and KaiC binding 

KaiB binds to phosphorylated KaiC in the evening, inactivating KaiA

SasA competes with KaiB to bind to KaiC, leading to RpaA phosphorylation

Answer: KaiA senses light during the day, stimulating KaiB and facilitates KaiB and KaiC binding

True or False: If you take a northern pole magnetotactic bacteria and drop it on the south pole, it has no way of reorienting itself and will certainly die.

Answer: False b/c motility: Allows bacteria to sense and move toward favorable environments and away from harmful ones

True or False: In Aerotaxis, Aer and Tsr are dependent on each other to properly guide the bacteria.

Answer: False

True or False: Bacterial fimbriae are assembled from the tip to the base, unlike bacterial flagella, that are assembled from the base to the tip.

Answer: False b/c fimbriae is base to tip and bacterial flagella grows from tip to base

True or False: E. coli have 5 differing MCPs that can sense multiple differing chemical and physical conditions.

Answer: True b/c Tsr, Tar, Trg, Tap, Aer

True or False: Spirochetes use polar flagella and lateral flagella for their swimming motility.

Answer: False b/c uses periplasmic flagella

True or False: When bacteria are in the presence of high concentrations of deterrents, they will methylate their MCPs to move in the counterclockwise rotation.

Answer: False b/c high deterrent concentration = increased repellent → demethylates MCP → return to CCW rotation

True or False: The type IV pili in Pseudomonas aeruginosa can be used to sense surfaces and the resistance in retraction leads to decreased intracellular cAMP levels.

Answer: False b/c leads to increased intracellular cAMP

True or False: For bacteria to run/move forward, they require their motors to move in the counterclockwise direction.

Answer: True b/c CCW: smooth forward movement (run). CW: tumble

True or False: Archeal Flagella are different from bacterial flagella in every aspect EXCEPT for their flagellar filaments, which are identical.

Answer: False

True or False: Even without membranes or protein shells, proteins can form distinct compartments in the bacterial cytoplasm.

Answer: True

True or False: Chemoattractants tend to be hydrophobic, leading to continued counterclockwise rotations of bacterial flagella.

Answer: False

Reasoning: Hydrophilic attractants CCW run & Away from hydrophobic repellents CW tumbles

True or False: E. coli is a type of gram negative bacteria, as it does not have a periplasmic space.

Answer: False b/c E-coil is gram negative but has outer membrane, specially inner & outer periplasmic space

True or False: Bacterial transduction occurs when a bacteriophage injects bacterial DNA from another bacteria into their new host.

Answer: True

True or False: One mechanism of antimicrobial resistance is bacteria producing beta-lactamases that degrade the purine rings of antibiotics.

Answer: False b/c degrade lactam ring of antibiotics

True or False: Antimicrobial resistance occurs when bacteria are under selective pressure.

Answer: True

True or False: When ppGpp is in high concentrations, bacteria are signalled that they are in a high stress environment, and that they need to increase their growth rate.

Answer: False b/c slow growth rate

True or False: The bacterial capsule is helpful in evading the host immune system.

Answer: True

True or False: Like bacterial flagella and F-type ATPases, the flagella of archaea are also powered by the diffusion of protons down their concentration gradient.

Answer: False b/c Archael is ATP-powered, not proton powered

True or False: Obligate anaerobes want to travel to the air-water interface.

Answer: False b/c O2 independent and swim deeper down, away from liquid air surface

Which of the following best describes flagellar swimming motility?

A. It occurs in polar flagella and is powered by the proton motive force

B. It occurs in lateral flagella and is powered by the proton motive force

C. It occurs in polar flagella and is powered by the sodium motive force

D. It occurs in lateral flagella and is powered by the sodium motive force

Answer: C. It occurs in polar flagella and is powered by the sodium motive force

Western diets can cause issues in the gut microbiome of humans. Why is this the case?

A. High fat can cause low-grade systemic inflammation

B. High fat can drive chronic diseases in the gut

C. High fat can cause increased chances of developing insulin resistance

D. All of the above

Answer: D. All of the above

What is true about bacterial fimbriae or bacterial flagella?

A. Bacterial fimbriae are hollow tubes that allow for adhesion

B. Bacterial flagella are non-hollow tubes used for motility

C. Bacterial flagella are hollow tubes that have their newer components attached to the tip

D. Bacterial flagella are hollow tubes that have their newer components attached to the base

Answer: C. Bacterial flagella are hollow tubes that have their newer components attached to the tip

Which of the following are associated with multiple different directed movement methods (like chemotaxis, thermotaxis, etc)?

A. Tsr

B. Aer

C. Trg

D. Tap

Answer: A. Tsr

An increase in intracellular cAMP in Pseudomonas aeruginosa is associated with which of the following?

A. An increase in flagellar genes to increase rotations, leading to the production of virulence factors

B. A decrease in the resistance of their type IV pili contracting, leading to increased production of virulence factors

C. An decrease in flagellar rotations due to decreased MotAB activity

D. A decrease in flagellar rotations due to surface impedance

Answer: D. A decrease in flagellar rotations due to surface impedance

What is true about virulence factor production in Pseudomonas aeruginosa?

A. They become translated once there are high concentrations of intracellular cAMP.

B. There are under 100 different types of these genes that allow for the modulation of their hosts to promote bacterial survival and proliferation

C. They become translated once there are low concentrations of intracellular cAMP.

D. They become translated once they have full control of their flagella rotation.

Answer: A. They become translated once there are high concentrations of intracellular cAMP.

What type of movement would you expect if a bacterium is in a high deterrent concentration gradient?

A. CheA will phosphorylate CheY into CheY-P, leading to methylation and causing continuation of the counterclockwise rotation

B. CheA will phosphorylate CheB into CheB-P , leading to demethylation of the MCPs resulting in lower concentrations of active CheA which decreases CheY-P, causing continuation of the clockwise rotation

C. CheA will phosphorylate CheB into CheB-P, leading to demethylation of the MCPs and resulting in lower concentrations of active CheA which decreases CheY-P, causing return to counterclockwise rotation

D. CheA will phosphorylate CheY to CheY-P, causing its binding to FliFGMN in the basal body of the flagellum and leading to counterclockwise rotation

Answer: C. CheA will phosphorylate CheB into CheB-P, leading to demethylation of the MCPs and resulting in lower concentrations of active CheA which decreases CheY-P, causing return to counterclockwise rotation

Enterohemorrhagic E. coli have a set of genes under the LEE umbrella whose expression is controlled by a multitude of different conditions. What is one of these conditions?

A. Acidic pH after leaving the stomach

B. Basic pH after leaving the stomach

C. Reduced oxygen concentrations in the intestines

D. None of the above

Answer: C. Reduced oxygen concentrations in the intestines

Bacterial persistence is classified into two categories of origin. Which one of the following is true?

A. Type II originators arise through environmental stressors, like low nutrients B. Type II originators arise through low environmental stress

C. Type I originators arise through random mutations

D. Type I originators arise through environmental stressors, like low nutrients

Answer: D. Type I originators arise through environmental stressors, like low nutrients

For swimming movement in bacteria, which proteins are exclusively important for chemotaxis?

A. MotAB

B. CheT

C. The L and P-rings of the flagellum

D. The MCPs

Answer: D. The MCPs

What is sensed in Aerotaxis in E. coli?

A. Concentration of O₂ in the environment

B. Concentration of reduced FAD in the cell

C. The pmf across the cytoplasmic membrane of the cell

D. B and C

E. All of the above

Answer: D. B and C

Pilin-based nanowires are important due to their ability to…

A. Inhibit electron flow due to the scarcity and placement of their aromatic amino acids

B. Regulate persistent bacterial functions

C. Conduct long-range electron transport to extracellular electron acceptors, like iron oxides

D. Act as long, membrane-bound structures that are primarily responsible for motility

Answer: C. Conduct long-range electron transport to extracellular electron acceptors, like iron oxides

When bacterial flagella become mutated so that they lose function, multiple phenotypes can arise. Which is one of these?

A. Intact flagella with complete motor function

B. Intact flagella with no chemotactic ability

C. Non-intact flagella with motor function

D. Intact flagella with chemotactic ability

Answer: B. Intact flagella with no chemotactic ability

Which of the following best describes an example of a mutualistic relationship in the gut microbiome?

A. Fermenters in our microbiome break down dietary fibers into SCFAs which help regulate inflammation, metabolism, and homeostasis.

B. H. pylori causes chronic infections that can lead to stomach cancer.

C. C. difficile rapidly proliferates in the gut after exposure to antibiotics, disrupting the gut microbiome.

D. A and C

Answer: A. Fermenters in our microbiome break down dietary fibers into SCFAs which help regulate inflammation, metabolism, and homeostasis.

Why is biofilm formation very advantageous for bacteria?

A. It allows for lower levels of conjugation, as there is no need to exchange genetic material because the biofilm already helps them to survive in many different niches.

B. It allows for better protection of the aerobic bacteria at the core of the biofilm, as they cannot survive in the presence of oxygen.

C. It allows for protection against antibiotics through the production of plasmids that are antibiotic resistant.

D. It creates a community of bacteria that can better adapt to their environments through better quorum sensing communication, nutrient cycling, and resistance to antibiotics.

Answer: D. It creates a community of bacteria that can better adapt to their environments through better quorum sensing communication, nutrient cycling, and resistance to antibiotics.

Why is the MotA and MotB complex important?

A. It allows for the transmembrane export of Hydrogen ions (protons) out of the cytoplasm for movement

B. It allows for the transmembrane import of Hydrogen ions (protons) into the cytoplasm for movement

C. It supplies structural support for the flagellar motor

D. None of the above

Answer: B. It allows for the transmembrane import of Hydrogen ions (protons) into the cytoplasm for movement

What are ways that bacteria can obtain genetic material from another bacterium?

A. Conjugation

B. Transformation

C. Transduction

D. All of the above

Answer: D. All of the above

Which of the following is the ion selector for the bacterial flagellum?

A. HAP2

B. MotAB

C. Rhodopsin

D. FliG

Answer: B. MotAB

When a bacterial cell goes from swimming to swarming motility, what is the most significant change that happens to the cell?

A. In swarming motility, all flagella begin to rotate counterclockwise (CCW) instead of clockwise (CW) in swimming

B. Far less ATP is being used for swarming than swimming

C. The new flagella for swarming motility grow from the periplasm

D. The morphology of the cell changes to a more elongated shape

Answer: D. The morphology of the cell changes to a more elongated shape

Which of the following is true about GroEL/ES?

A. GroEL is the barrel section that captures fully folded (normal) proteins, while GroES is the cap

B. GroES is the barrel section that indiscriminately fully folds (normal) proteins, while GroEL is the cap

C. GroEL is the barrel section that captures and folds partially or unfolded proteins, while GroES is the cap

D. GroES is the barrel section that captures partially or unfolded proteins, while GroEL is the cap

Answer: C. GroEL is the barrel section that captures and folds partially or unfolded proteins, while GroES is the cap