Deck 5: Cell Biology of Bacteria and Eukaryotes

Question 1

In the image shown the circles and squares indicate molecules.The circles are at a higher concentration outside the cell and the squares are at a higher concentration inside the cell.Which of the following statements is correct?

A) Energy is released if the circles move into the cell or if the squares move out of the cell.
B) Energy is released if the circles move into the cell or if the squares move into the cell.
C) Energy is released if the circles move out of the cell or if the squares move out of the cell.
D) Energy is released if the circles move out of the cell or if the squares move into the cell.

Answer 1

A

Question 2

In this scanning electron micrograph of Borrelia burgdorferi,which of the following structures is visible?

A) the outer sheath
B) cytoplasmic filaments
C) the genome
D) flagellar motors

Answer 2

A

Question 3

In this model of a Gram-negative bacterial cell envelope,which line is drawn to the periplasm?

A) 1
B) 2
C) 3
D) 4

Answer 3

C

Question 4

Which of the following is FALSE of teichoic acids?

A) They reinforce the cell wall.
B) They may help pathogens attach to host cells.
C) They are recognized by the host immune system.
D) They repel the Gram stain.

Question 5

How does the cell wall protect bacterial cells from osmotic shock?

A) The wall forms a rigid cage that withstands turgor pressure.
B) The wall is impermeable to water, preventing turgor pressure.
C) The wall is impermeable to ions and other solutes, preventing osmotic imbalance.
D) The wall ensures cells are only found in environments where turgor pressure will not occur.

Question 6

In an E.coli cell,which molecule is found in only 1-2 copies per cell?

A) DNA
B) RNA
C) protein
D) phospholipids

Question 7

In this model of a Gram-negative bacterial cell envelope,which line is drawn to lipopolysaccharides?

A) 1
B) 2
C) 3
D) 4

Question 8

In this image the energy released by the transport of the circles out of the cell is used to drive the import of the squares into the cell.This is an example of

A) passive transport.
B) facilitated diffusion.
C) symport coupled transport.
D) antiport coupled transport.

Question 9

In Gram-negative bacteria,peptidoglycan is found in the

A) cytoplasm.
B) inner membrane.
C) outer membrane.
D) periplasm.

Question 10

Lipopolysaccharides are found in

A) Gram-positive bacteria.
B) Gram-negative bacteria.
C) archaea.
D) eukaryotic microbes.

Question 11

Mycoplasma lost their cell walls via reductive evolution.This was possible because

A) their cell membranes became extra thick to compensate.
B) it allowed them to not be sensitive to antibiotics that target the cell wall.
C) as obligate parasites they live in environments with constant osmolarity.
D) they live in soils with plenty of available moisture.

Question 12

This image models a

A) Gram-positive cell envelope.
B) Gram-negative cell envelope.
C) eukaryotic cell membrane.
D) mycobacterial envelope.

Question 13

In Gram-negative bacteria the cell membrane separates the

A) periplasm from the external environment.
B) cytoplasm from the external environment.
C) cytoplasm from the nucleoid.
D) DNA from the RNA.

Question 14

Which bacterial cellular constituent is most liable to change under changing environmental conditions?

A) DNA
B) peptidoglycan
C) polyamines
D) proteins

Question 15

The bacterial cell wall is an attractive target for antibiotics because

A) bacterial cells cannot develop resistance to antibiotics that target the cell wall.
B) animal cells lack a cell wall.
C) the cell wall is unimportant for bacterial survival.
D) the cell wall is the only structure bacteria require for survival.

Question 16

The majority of the bacterial cell cytoplasm (by total weight)is

A) DNA.
B) RNA.
C) protein.
D) water.

Question 17

What is the cellular target of penicillin (the first antibiotic discovered)?

A) the DNA genome
B) the cell wall
C) ribosomes
D) ABC transporters

Question 18

In this image a transmembrane protein moves circles out of the cell,providing energy to move squares into the cell.Which of the following is correct?

A) Both the circles and the squares move down their concentration gradients.
B) Both the circles and the squares move against their concentration gradients.
C) The circles move down their concentration gradient and the squares move against their concentration gradient.
D) The circles move against their concentration gradient and the squares move down their concentration gradient.

Question 19

The cell wall is part of the

A) cell membrane.
B) cytoplasm.
C) cell envelope.
D) proteome.

Question 20

The cell membrane stores energy by maintaining a separation of

A) DNA.
B) proteins.
C) ions.
D) lipids.

Question 21

Ribosomes associate with which endomembrane organelle?

A) Golgi complex
B) endoplasmic reticulum
C) lysosomes
D) peroxisomes

Question 22

Which organelle arose via endosymbiosis?

A) chloroplast
B) Golgi apparatus
C) lysosome
D) nucleus

Question 23

Flagella are required for bacterial

A) chemotaxis.
B) growth.
C) adherence.
D) buoyancy.

Question 24

Which of the following shows the correct path a secreted protein takes in a eukaryotic cell?

A) Golgi complex, rough ER, vesicle, cell membrane
B) vesicle, rough ER, Golgi complex, cell membrane
C) rough ER, Golgi complex, vesicle, cell membrane
D) rough ER, Golgi complex, cell membrane, vesicle

Question 25

ATP synthase is found in bacterial cell membranes.In eukaryotic cells,ATP synthase is found in the

A) cell membrane.
B) cytoplasm.
C) mitochondrial inner membrane.
D) mitochondrial matrix.

Question 26

Which of the following is a function of lipopolysaccharide?

A) helps cells resist phagocytosis
B) aids in outer membrane cell wall attachment
C) allows for mobility to promote chemotaxis
D) provides energy to the cell

Question 27

Magnetotactic bacteria swim along a magnetic field.To do this these bacteria have which of the following structures that are not present in all bacterial species?

A) storage granules
B) sulfur granules
C) flagella
D) gas vesicles

Question 28

Which organelle houses a eukaryotic cell's genome?

A) rough endoplasmic reticulum
B) contractile vacuole
C) ribosome
D) nucleus

Question 29

Pili and stalks enable bacterial

A) adherence.
B) chemotaxis.
C) photosynthesis.
D) symport.

Question 30

Which of the following is true of growing bacteria?

A) DNA synthesis occurs continuously.
B) DNA synthesis occurs during a defined period.
C) They suspend flagella rotation to put energy toward DNA replication.
D) DNA synthesis cannot occur at the same time as transcription.

Question 31

Which of the following structures is obligatory for all bacterial cells?

A) nucleoid
B) flagella
C) pili
D) magnetosomes

Question 32

This transmission electron micrograph of a marine microbe shows internal structures such as thylakoids.This microbe has what capability that is not present in all bacterial species?

A) adherence
B) chemotaxis
C) DNA replication
D) photosynthesis

Question 33

The arrows indicate the partition that separates a bacterial cell into two new daughter cells.This partition is called the

A) stalk.
B) S-layer.
C) septum.
D) termination site.

Question 34

While most wild E.coli usually have flagella,many lab strains have lost their flagella.What is a likely cause of this loss?

A) reductive evolution due to an increased need for chemotaxis
B) reductive evolution due to an unchanging environment
C) reductive evolution due to an increased need for magnetotaxis
D) reductive evolution due to a decreased need for magnetotaxis

Question 35

Murein lipoprotein is a part of the ________ of the ________.

A) outer leaflet, outer membrane.
B) inner leaflet, outer membrane.
C) outer leaflet, inner membrane.
D) inner leaflet, inner membrane.

Question 36

This transmission electron micrograph shows a

A) Gram-positive cell envelope.
B) Gram-negative cell envelope.
C) eukaryotic cell membrane.
D) mycobacterial envelope.

Question 37

Bacterial cells that expand their cell walls during septation (not before)and septate in parallel planes will form

A) chains of rods (bacilli).
B) tetrads of rods (bacilli).
C) chains of spheres (cocci).
D) tetrads of spheres (cocci).

Question 38

Which of the following helps compact bacterial DNA?

A) the origin of replication site
B) supercoils
C) porins
D) pilins

Question 39

Which organelle is NOT part of the endomembrane system?

A) mitochondrion
B) lysosome
C) peroxisome
D) Golgi complex

Question 40

This electron micrograph shows staphylococci,spherical cells that cluster together like grape bunches.This form occurs when cell wall expansion occurs

A) prior to septation and septation occurs in parallel planes.
B) prior to septation and septation occurs in random orientations.
C) during septation and septation occurs in parallel planes.
D) during septation and septation occurs in random orientations.

Question 41

Describe the two types of energy cells used to move molecules across membranes against their concentration gradients.

Question 42

The bacterial nucleoid contains loops of DNA that emanate from a central point called the ________.

Question 43

CASE HISTORY
Jennifer,age 23,had just graduated from college with a Fulbright fellowship to study sociology in Africa.Before leaving the United States,she obtained a routine physical exam at a large city hospital.Upon returning home from the hospital,she developed a swelling in her leg.When she returned to the hospital,she was told that the swelling represented an allergic reaction and was given anti-inflammatory agents.The swelling grew,and within a day the skin ruptured with a bloody discharge.Upon return to the emergency room,Jennifer at last received the correct diagnosis of methicillin-resistant staphylococcus infection (MRSA).A nurse commented that hospital visitors can acquire MRSA;the infectious agent is endemic at many hospitals in the United States and is very difficult to eradicate.She showed Jennifer a micrograph of the bacteria,Staphylococcus aureus,which septate in alternating division planes,thus forming clusters of cells.Jennifer required many weeks of treatment with the antibiotics doxycycline and clindamycin (inhibits protein synthesis)before the infection resolved,and she had to postpone her fellowship for a year.
Methicillin,the antibiotic to which MRSA is characteristically resistant,targets the cell wall.Discuss the structure of the cell wall in a bacterial cell like those of MRSA and how antibiotics can target this structure without harming the patient.

Question 44

The ability of bacterial cells to swim toward favorable environments and away from harmful environments is known as ________.

Question 45

Explain how bacterial cells can divide so rapidly,some in as little as ten minutes between generations.

Question 46

In the process of ________,a vesicle fuses with the cell membrane,releasing vesicle contents into the extracellular environment.

Question 47

Would pili be more advantageous to bacteria in a rapidly changing or in an unchanging environment? Please explain your answer.

Question 48

CASE HISTORY
Sharon,the CEO of a start-up company,lives in Westchester County,a wooded community north of New York City.She spends her summer weekends e-mailing her managers from the outdoor deck of her home,shaded by tall oak trees.The acorns attract mice and deer,and the leaf litter is full of ticks (Ixodes scapularis).
One evening Sharon's husband noticed a red rash on her back,consisting of a ring shape several centimeters across,surrounding another red spot in the middle.Sharon recalled seeing this "bull's-eye" type of rash on the Internet.The rash was described as the hallmark of Lyme disease,or borreliosis,caused in the United States by the tick-borne bacterium Borrelia burgdorferi (in Europe,by the closely related species Borrelia afzelii).The distinctive rash,erythema migrans ("migrating redness"),begins at the site of a tick bite and expands concentrically as the bacteria migrate outward.Sharon recalled that a neighbor's child had suffered crippling arthritis caused by an undetected case of Lyme disease.Another neighbor who contracted Lyme disease had suffered from meningitis (inflammation of the brain lining)and neurological abnormalities,including facial paralysis,ultimately losing his job and his million-dollar home.
The next day Sharon went to her doctor and was treated with the antibiotic doxycycline,a tetracycline derivative that targets the bacterial ribosome.Doxycycline is the antibiotic of choice for B.burgdorferi.Sharon was fortunate to make a full recovery before serious symptoms appeared.
The bull's-eye rash that is a hallmark of Sharon's infection is associated with movement of the bacteria from the initial site of tick bite and infection.Discuss how these bacteria move and the cell structures associated with movement.

Question 49

The region within the inner and outer membranes of Gram-negative bacteria is known as the ________.

Question 50

What evidence would suggest that a newly discovered eukaryotic organelle was formed via endosymbiosis?

Question 51

Compare and contrast the Gram-negative and Gram-positive cell envelopes.

Question 52

If Na⁺ is at a higher concentration outside a cell than inside,________ is the most likely means for sodium ions to enter the cell (and for nothing else to enter or leave).

Question 53

CASE HISTORY
In the Indian state of Bihar,a school nurse noticed that a 13-year-old boy,Naranjan,had swelling on his nose and lips.When questioned,Naranjan complained of a pruritic (itchy)rash on his arms and legs.Upon examination,the nurse found pale patches of skin on his back.The pale patches lacked sensation,and there was partial loss of sensation in Naranjan's wrists and forearms.The patient was diagnosed with leprosy,caused by the bacterium Mycobacterium leprae.The bacteria stain acid-fast and are spread primarily by nasal secretions.For unknown reasons,only 5% of people exposed to the bacteria are susceptible to infection.In a susceptible host,the bacteria can grow slowly for many years without symptoms.They infect the peripheral nerves,causing loss of sensation,and the body's immune reaction generates skin lesions.To halt the disease,Naranjan was started on a two-year course of multidrug therapy combining dapsone,clofazimine,and rifampin.To monitor hepatotoxicity,liver function tests were ordered.Naranjan's family and neighbors were screened;one member,an uncle,showed skin lesions.The uncle was treated also.Leprosy is difficult to eradicate because of the long incubation period and because people hide their symptoms,fearing stigma as "lepers."
Mycobacterium leprae,or leprosy disease,often takes years to develop.Naranjan must use a long-term multidrug therapy to cure it.Why is it necessary to take the drugs for such a long period,and why must he take so many drugs at once?

A) Mycobacteria are Gram-negative organisms. They must be killed slowly to prevent release of toxic LPS.
B) Mycolic acid within the cell wall reduces nutrient uptake, resulting in slow growth, and excludes some antibiotics.
C) Mycobacteria are all highly resistant to antibiotics.
D) Mycobacteria don't have cell walls, so must be treated with antibiotics that target other structures.