Deck 3: Cell Structure and Function

Question 1

The 2D-PAGE separation of macromolecules is dependent on all of the following EXCEPT:

A) size
B) charge
C) pH
D) DNA sequence
E) voltage applied

Answer 1

D

Question 2

__________ is impractical for proteins of a flexible nature.

A) Electrophoresis
B) Sonication
C) X-ray crystallography
D) Fractionation
E) Ultracentrifugation

Answer 2

C

Question 3

__________ reinforce and stiffen membranes in bacteria.

A) Hopanoids
B) Plyamines
C) Sterols
D) Peptidoglycans
E) Lipids

Answer 3

A

Question 4

Polyamines are __________ charged when the pH is near neutral.

A) not
B) negatively
C) positively
D) super
E) randomly

Question 5

The concentration of __________ increases when bacteria are starving or in the stationary phase.

A) lipoproteins
B) proteins
C) cholesterols
D) terpenoids
E) cardiolipin

Question 6

The proteins expressed by a cell under given conditions are known collectively as a:

A) proteome
B) genome
C) protease
D) gene
E) ribosome

Question 7

All of the following statements regarding phospholipids of the cell membrane are true EXCEPT:

A) They consist of glycerol with ester links to two fatty acids and a phosphoryl group.
B) They impart rigidity to the membrane.
C) All face each other, tail to tail.
D) The two layers in the bilayer are called leaflets.
E) They give the membrane a consistent thickness.

Question 8

All archaeal phospholipids have a(n) __________ link between glycerol and the lipid component.

A) ester
B) ether
C) ethanolamine
D) unsaturated
E) phosphatidyl

Question 9

Transport __________ mediate both active and passive transport.

A) polysaccharides
B) proteins
C) lipids
D) hopanoids
E) sterols

Question 10

The capsule polysaccharides form a slippery mucous layer that inhibits:

A) diffusion
B) phagocytosis
C) attachment
D) lysis
E) osmosis

Question 11

__________ stabilize ribosomes during translation.

A) Polysaccharides
B) Nucleic acids
C) Polyamines
D) Lipids
E) Phospholipids

Question 12

We cannot literally see the molecules within a cell, but __________ and __________ analysis generate a remarkably detailed view.

A) structural; genetic
B) microscopy; genetic
C) structural; subcellular
D) microscopy; subcellular
E) chemical; genetic

Question 13

A medically important example of active transport is that of drug __________ proteins powered by the hydrogen ion gradient.

A) efflux
B) porin
C) membrane-permeant
D) diffusion
E) lysis

Question 14

Specific membrane components, particularly __________, determine which substances are transported across the membrane.

A) phospholipids
B) proteins
C) ions
D) polysaccharides
E) leaflets

Question 15

Profiles of which component of the membrane may be used to identify certain kinds of pathogens?

A) lipoproteins
B) proteins
C) fatty acids
D) polysaccharides
E) leaflets

Question 16

Fred Neidhardt carried out experiments to define the proteome of a cell by using:

A) genetic analysis
B) X-ray crystallography
C) two-dimensional polyacrylamide gel electrophoresis
D) protein synthesis
E) subcellular fractionation

Question 17

The most highly expressed proteins in a cell are the __________ proteins and the __________ factors.

A) transport; transcription
B) ribosomal; translation
C) structural; replication
D) enzymatic; catalytic
E) replication; transcription

Question 18

Functions of the cytoplasmic membrane include all of the following EXCEPT:

A) permeability barrier
B) assemble proteins
C) store energy
D) transport
E) structural support

Question 19

E. coli and Sinorhizobium cell-surface proteins enable colonization of __________ and __________, respectively.

A) the human intestinal epithelium; animal skin
B) legume plants; the human intestinal epithelium
C) the human intestinal epithelium; legume plants
D) legume plants; animal skin
E) cantaloupe; spinach

Question 20

How many ATP molecules are needed by E. coli to transport vitamin B₁₂ across the inner cell membrane into the cytoplasm?

A) 0
B) 1
C) 2
D) 4
E) 8

Question 21

All of the following are true for DNA-binding proteins EXCEPT:

A) They determine the shape of the cell.
B) They condense prokaryotic DNA.
C) They can act as regulators of gene expression.
D) They can form protective crystalline structures around organized DNA.
E) They help to keep cells viable for a longer duration of time.

Question 22

What part of a cell is referred to as the sacculus?

A) nucleoid
B) cytoplasm
C) cell membrane
D) cell wall
E) outer membrane

Question 23

All of the following are components of peptidoglycan EXCEPT:

A) N-acetylglucosamine
B) N-acetylmuramic acid
C) lipopolysaccharide
D) amino acids
E) peptide cross-links

Question 24

Lipopolysaccharides are found in:

A) all bacteria
B) Gram-positive bacteria
C) Gram-negative bacteria
D) archaea
E) eukaryotes

Question 25

Which of the following is true of Fts proteins?

A) They form a ring in the area where cell division will occur.
B) They aid in DNA replication.
C) They are involved in peptidoglycan synthesis.
D) They are involved in making proteins.
E) They are important in transcription.

Question 26

All of the following are true statements about bacterial S-layers EXCEPT:

A) They are commonly found in Gram-positive cells as well as in archaea.
B) They are a crystalline layer consisting of protein or glycoprotein.
C) They present a formidable physical barrier to predators or parasites.
D) They are found in bacteria freshly isolated from natural sources.
E) They are found in bacteria isolated from laboratory cultures.

Question 27

The __________ is the region between the cytoplasmic membrane and the outer membrane in Gram-negative cells.

A) periplasm
B) cytoplasm
C) lysozyme
D) lipopolysaccharide
E) S-layer

Question 28

All of the following are true about prokaryotic outer membranes EXCEPT:

A) They are lipid bilayers composed of identical phospholipids.
B) They are found only in Gram-negative bacteria.
C) They contain endotoxin.
D) They contain proteins involved in transport.
E) They contain lipopolysaccharide.

Question 29

All of the following are true of supercoiling in chromosomal DNA EXCEPT:

A) DNA doubles back and twists upon itself.
B) It facilitates RNA transcription.
C) It results in compaction.
D) It is generated by gyrase.
E) It is maintained by DNA-binding proteins.

Question 30

Which of the following molecules can be easily transported by passive diffusion?

A) HCHO
B) CH₃COOH
C) H₂O
D) CO₂
E) both C and D

Question 31

All of the following represent components of eukaryotic organisms that help avoid osmotic shock EXCEPT:

A) cellulose fibers
B) chitin
C) silicate exoskeleton
D) contractile vacuole
E) peptidoglycan

Question 32

A __________ is a term used to designate a single messenger RNA molecule being translated by multiple ribosomes.

A) coupled
B) periplasm
C) carboxysome
D) thylakoid
E) polysome

Question 33

Efflux pumps send antibiotics such as tetracycline, which binds to the 30S subunit of bacterial ribosomes, out of the bacterial cells, enabling them to grow in the presence of antibiotics. Which of the following therapeutic approaches will be least effective?

A) Switch to an antibiotic that is not a substrate of the efflux pump.
B) Augment the treatment with an efflux inhibitor.
C) Increase the concentration of tetracycline.
D) Augment the treatment with an ATP synthase inhibitor.
E) None of the above approaches will be effective.

Question 34

The partition that is a result of the inward growth of the cell envelope from opposite directions is known as the:

A) divisome
B) septum
C) wall
D) colony
E) Z-ring

Question 35

In Gram-negative bacteria, ATP synthase is typically found in:

A) cytoplasm
B) peptidoglycan layer
C) cell wall
D) inner membrane
E) outer membrane

Question 36

The thin layer of peptidoglycan in Gram-negative cells is believed, based on calculations of __________, to be one or two sheets.

A) shape
B) genetic analysis
C) width
D) X-ray crystallography
E) molecular density

Question 37

Eukaryotic microbes that lack a cell wall possess __________ to circumvent osmotic shock.

A) Golgi bodies
B) contractile vacuoles
C) endoplasmic reticulum
D) lysosomes
E) gas vesicles

Question 38

Which is NOT a component of any bacterial cell's wall?

A) peptidoglycan
B) teichoic acids
C) N-acetylmuramic acid
D) cellulose
E) L-lysine

Question 39

The bacterial cell wall of Mycobacteria is highly hydrophobic due to presence of:

A) lipoproteins
B) phenolic glycolipids
C) phospholipids
D) polysaccharides
E) glycoproteins

Question 40

The lipopolysaccharide of the outer membrane is of medical importance because it acts as a(n):

A) endotoxin
B) exotoxin
C) toxoid
D) enterotoxin
E) antibiotic

Question 41

Describe four ways cells can be broken open in order to isolate the cellular components.

Question 42

Which of the following is described as an attachment organelle that is a membrane-bound extension of the cytoplasm?

A) pili
B) fimbriae
C) sex pili
D) stalks
E) flagella

Question 43

The bacterial membrane ATP synthase has two subunits. What is the location of each?

Question 44

Ribosomes isolated by centrifugation are still active. What evidence demonstrates this?

Question 45

All of the following are used by prokaryotic cells for attaching to solid surfaces EXCEPT:

A) endospore
B) capsule
C) stalks
D) fimbriae
E) pili

Question 46

What are some of the limitations of X-ray crystallography?

Question 47

Prokaryotic genomes are more compact than eukaryotes, and the content of nucleic acids in prokaryotes is much higher than in most eukaryotes. Explain this. Why is it necessary for prokaryotes' survival?

Question 48

Explain what happens when a cell comes into contact with water or with ethanol. Why is 70% ethanol commonly used to treat wounds and surfaces?

Question 49

How could you use green fluorescent protein as a reporter gene to compare production of a specific protein in a cell culture when the culture is growing under different environmental conditions?

Question 50

Which of the following is true regarding the asymmetrical cell division of Caulobacter crescentus?

A) It protects the Caulobacter crescentus from predators.
B) It is a result of sexual reproduction.
C) It is a result of polar aging.
D) It results in two cell types (i.e., stalked cell and swarmer).
E) It results in two cell types, each with a monotrichous flagellum.

Question 51

Describe the Gram-negative cell envelope. Why are porins necessary in the outer membrane of Gram-negative cells?

Question 52

Directed movements toward or away from a chemical or physical signal are known as:

A) gliding
B) flagellation
C) chemotaxis
D) locomotion
E) slime layer

Question 53

List and briefly describe four components of a typical bacterial cell.

Question 54

The bacterial flagellum is a helical protein filament whose __________ motor moves the cell in search of a more favorable environment.

A) shaking
B) vibrating
C) wavelike
D) whiplike
E) propeller-like

Question 55

Which of the following statements about the prokaryotic flagella is INCORRECT?

A) It is driven by the cell's transmembrane proton current.
B) It is embedded in the layers of the cell envelope.
C) It is observed by electron microscopy.
D) It moves with a whiplike motion.
E) It is used for chemotaxis.

Question 56

Light is harvested by protein complexes called:

A) thylakoids
B) carboxysomes
C) gas vesicles
D) storage granules
E) magnetosomes

Question 57

Which of the following materials found in storage granules is used as an energy source?

A) gas vesicle
B) sulfur
C) polyphosphate
D) glycogen
E) magnetosome

Question 58

What unusual lipids are found in mycobacteria and of what benefit are they to these bacteria?

Question 59

Which name refers to having flagella attached at one or both ends of the cell?

A) peritrichous
B) lophotrichous
C) monotrichous
D) bitrichous
E) flagellated

Question 60

Why can't most kinds of bacteria be eaten as a major part of our diet?

Question 61

Describe two specialized structures that photosynthetic organisms may possess, and explain why the structures are needed by these organisms.

Question 62

Compare and contrast FtsZ and tubulin. Why do the similarities support evolution of prokaryotes and eukaryotes from a common ancestor?

Question 63

When designing an antibiotic, one should target what aspect of a prokaryote? Give at least two specific examples of drugs and their target.

Question 64

Describe how and why magnetotactic bacteria might be used in wastewater management.

Question 65

Which age class of M. tuberculosis (age 1 or age 3) do you think would be more resistant to quinolones, which block gyrase that supercoils DNA?

Question 66

Briefly describe the transertion process. Why is this process important for insertion of proteins into the cell membrane?

Question 67

How can some prokaryotes double in as little as ten minutes?

Question 68

From your knowledge of Gram-positive and Gram-negative cell envelopes, why would penicillin be more effective in killing Gram-positive organisms than Gram-negative organisms?

Question 69

Explain the movement of a bacterium possessing flagella away from a toxic chemical.