Topic 2 - Bacteria - Clickers Flashcards
Which bacterium has the highest surface-to-volume ratio?
a) Medium coccus
b) Large coccus
c) Thin rod
c) Thin rod
Thin rods have the highest surface-to-volume ratio, allowing for more efficient nutrient exchange and waste removal.
Which bacterium has the highest surface-to-volume ratio?
a) Thin rod
b) Thick rod
a) Thin rod
A thinner structure increases the surface area relative to volume, optimizing exchange processes.
Which bacterium has the highest surface-to-volume ratio?
a) Large coccus
b) Thin short rod
c) Thin long rod
b) Thin short rod
Shorter rods maximize surface area while minimizing volume, leading to higher ratios.
Most…
a) Viruses are larger than most archaea.
b) Bacteria are larger than most archaea.
c) Archaea are larger than most eukaryotes.
d) Eukaryotes are larger than most bacteria.
e) Archaea are larger than most bacteria.
d) Eukaryotes are larger than most bacteria
Eukaryotic cells are typically larger and more complex compared to bacterial cells.
Which bacterium has the highest surface-to-volume ratio?
a) Large coccus
b) Medium coccus
c) Really long thin rod
c) Really long thin rod
Elongated thin shapes increase the surface-to-volume ratio significantly compared to spherical shapes.
As a bacterium, living in your own large intestine, what shape would you likely choose?
a) Really long thin rod
b) Medium coccus
c) Large coccus
c) Large coccus
Larger, more spherical shapes reduce surface area exposure, which can be beneficial in nutrient-rich environments like the intestine.
What is responsible for supercoiling of DNA in the nucleoid?
a) Anions
b) Positively charged proteins
c) Cations
d) Topoisomerases
e) Negatively charged proteins
d) Topoisomerases
Topoisomerases are enzymes that help in supercoiling DNA, crucial for packing DNA in the nucleoid.
Which of the following is a component of the cytoplasm found only in bacterial cells?
a) Proteins
b) Gas vesicles
c) Ribosomes
d) None of the above
e) Magnetosomes
e) Magnetosomes
Magnetosomes are unique to certain bacterial cells and help in navigation based on Earth’s magnetic field.
Which of the following is NOT a function associated with the cytoskeleton of bacteria?
a) Compartmentalizing the cytoplasm
b) Localizing the division plane
c) Determining cell shape
d) Segregating chromosomes
a) Compartmentalizing the cytoplasm
The bacterial cytoskeleton does not compartmentalize the cytoplasm; this is a function seen in eukaryotes.
Which of these use ATP? Choose all that apply.
a) Facilitated diffusion
b) Partition proteins
c) Aquaporins
d) Protein secretion
e) ABC transporters
b) Partition proteins
Many protein secretion systems in bacteria, such as the Type I secretion system and Type III secretion system, are ATP-dependent. These systems use ATP to power the translocation of proteins across membranes.
d) Protein secretion
These proteins play a role in the segregation of chromosomes or plasmids during cell division. They use ATP hydrolysis to generate the energy required for the active movement of genetic material to ensure accurate distribution to daughter cells.
e) ABC transporters
ABC transporters are membrane proteins that use ATP to transport substances across the cell membrane.
A major difference between Gram-positive and Gram-negative bacterial cell envelopes is the presence of…
a) D-amino acids
b) Periplasm
c) Teichoic acids
d) Peptidoglycan
e) Transport proteins in the cytoplasmic membrane
c) Teichoic acids
Teichoic acids are found in the cell walls of Gram-positive bacteria and are absent in Gram-negative bacteria.
Which of these are not part of the cell envelope?
a) Periplasm
b) Inner membrane
c) Cell wall
d) Cytoplasm
e) Outer membrane
d) Cytoplasm
Explanation: The cytoplasm is located inside the cell, separate from the cell envelope, which consists of the inner membrane, periplasm, cell wall, and outer membrane.
What do you see? (pink rods, purple cocci)
a) G- rods, G+ cocci
b) G- rods, G- cocci
c) G+ rods, G- cocci
d) G+ rods, G+ cocci
a) G- rods, G+ cocci
Explanation: The pink color indicates Gram-negative (G-) rods, and the purple color indicates Gram-positive (G+) cocci, based on Gram staining results.
Which of the following is FALSE?
a) The nucleoid is surrounded by a double membrane.
b) Bactoprenol is a hydrophobic lipid carrier that helps translocate pentapeptide precursors.
c) MreB is homologous to actin and FtsZ is related to tubulin.
d) Morphology is of limited value in differentiating among species of bacteria.
e) Both Gram-positive and Gram-negative bacteria possess a periplasmic space.
a) The nucleoid is surrounded by a double membrane.
Explanation: The nucleoid is not surrounded by a double membrane; it is an irregularly shaped region within the cytoplasm where bacterial DNA is located.
Given the image of a cell envelope (top), what Gram stain outcome (bottom) would you expect?
a) Purple-stained cells (Gram-positive)
b) Pink-stained cells (Gram-negative)
a) Purple-stained cells (Gram-positive)
Explanation: The cell envelope shown has a thick peptidoglycan layer, which is characteristic of Gram-positive bacteria. During Gram staining, the thick peptidoglycan retains the crystal violet stain even after alcohol decolorization, resulting in purple-stained cells. Conversely, Gram-negative bacteria (pink-stained) have a thinner peptidoglycan layer and an outer membrane that does not retain the crystal violet after decolorization.
Forgetful student! You forgot the safranin! What colour will these be after this botched Gram stain?
a) Clear
b) Red
c) Purple
d) Brown
c) Purple
Explanation: In a Gram stain, the primary stain (crystal violet) binds to the thick peptidoglycan layer in Gram-positive bacteria, resulting in a purple color. The counterstain (safranin) is not necessary to see Gram-positive bacteria since they already retain the crystal violet dye. Omitting the safranin only affects Gram-negative bacteria, which would remain clear without it.
Which of the following is FALSE?
a) S layers are found on both Gram-positive and Gram-negative bacteria.
b) Capsules are found only for Gram-positive bacteria.
c) Lipopolysaccharide (LPS) is found only on Gram-negative bacteria.
d) Flagella are found on many Gram-positive and Gram-negative bacteria.
b) Capsules are found only for Gram-positive bacteria.
Explanation: Capsules are not exclusive to Gram-positive bacteria; they are found in both Gram-positive and Gram-negative bacteria, making this statement false.
Which one of these surface features contains cytoplasm?
a) Stalk
b) Fimbriae
c) Capsule
d) S-layer
e) Flagella
a) Stalk
Explanation: The stalk is an extension of the cytoplasm and contains cytoplasm, unlike the other structures listed, which are external appendages or protective layers.
Which of the following characteristics are used to classify bacteria?
a) Cell morphology
b) Gram reaction
c) Metabolism
d) DNA
e) All of these choices
e) All of these choices
Explanation: Bacteria are classified based on multiple characteristics, including their cell morphology, Gram reaction, metabolic capabilities, and genetic composition.
A type strain is… (choose the best answer)
a) A mutated strain created in the laboratory.
b) A unique bacterial species.
c) A representative reference specimen available in a central depository.
d) The first culture of a newly discovered bacterial species.
c) A representative reference specimen available in a central depository.
Explanation: A type strain is the reference specimen that serves as the standard for defining a bacterial species, typically stored in a central repository.
Find the CORRECT association.
a) Techoic acid – polysaccharide
b) S layer – polysaccharide
c) Lipopolysaccharide – cytoplasmic membrane
d) Capsule – protein
e) Glycine interbridges – Gram-negative bacteria
a) Techoic acid – polysaccharide
Explanation: Teichoic acids are polysaccharides found in the cell walls of Gram-positive bacteria, serving structural and functional roles.
What is the function of the S layer?
a) May be important for growth at high cell densities.
b) Is energetically ‘inexpensive’ to make.
c) Is not necessary in nutrient-poor environments.
d) May protect cells from viruses and predatory bacteria.
d) May protect cells from viruses and predatory bacteria.
Explanation: The S layer provides a protective barrier for bacterial cells, helping to shield them from external threats like viruses and predatory bacteria.
Which of the following flagellar arrangements might involve a flagellum at both ends of a cell?
a) Peritrichous
b) Amphitrichous
c) Monotrichous
d) Lophotrichous
e) Retrichous
b) Amphitrichous
Explanation: Amphitrichous refers to bacteria that have a single flagellum at both poles of the cell, enabling bidirectional movement.
During cell wall synthesis in bacteria, when does the pentapeptide become a tetrapeptide?
a) When transpeptidation occurs
b) When bactoprenol flips the precursor into the periplasm
c) When NAM is linked to bactoprenol
d) When transglycosylation occurs
a) When transpeptidation occurs
Explanation: Transpeptidation is the process that removes one amino acid from the pentapeptide, leaving a tetrapeptide during peptidoglycan cross-linking.
What is NOT a way by which bacteria compress their DNA?
a) Small positively charged proteins
b) Histones
c) Cations
d) DNA topoisomerases
b) Histones
Explanation: Bacteria do not use histones to compress their DNA. Instead, they rely on small positively charged proteins, cations, and DNA topoisomerases for DNA condensation.
Which of the following is found in the peptidoglycan layer of Gram-negative bacteria?
a) Lipoteichoic acid
b) Glycine interbridges
c) N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
d) Teichoic acid
e) Hopanoids
c) N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
Explanation: NAG and NAM are the main components of peptidoglycan, forming the structural backbone of bacterial cell walls.
All of the following compounds can be found in the bacterium Staphylococcus, except:
a) Lipid bilayer
b) FtsZ
c) MreB
d) Bactoprenol
e) Peptidoglycan
c) MreB
Explanation: MreB is typically found in rod-shaped bacteria to maintain their shape. Staphylococcus, being cocci, lacks MreB.
