Microbiology Quiz on Bacterial Structure and Function

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Questions and Answers

What is the key structural difference between Gram-positive and Gram-negative bacteria?

Presence of teichoic acids

Thickness of the cell wall (correct)

Presence of a capsule

Number of flagella

Which molecule is essential for cross-linking peptidoglycan chains in bacterial cell walls?

Diaminopimelic acid (correct)

L-alanine

N-acetylglucosamine (NAG)

N-acetylmuramic acid (NAM)

How is N-acetylmuramic acid (NAM) formed from N-acetylglucosamine (NAG) in bacterial cells?

Hydrolysis

Phosphorylation

Enzymatic conversion (correct)

Dehydration

What type of chemical bond is primarily used for cross-linking peptidoglycans in Gram-negative bacteria?

Peptide bond between amino acids Signup and view all the answers

Which of the following describes a primary function of the skin microbiota?

To maintain a healthy cutaneous barrier. Signup and view all the answers

What kind of amino acids are incorporated into the tetrapeptide of the peptidoglycan structure?

Both D- and L-amino acids Signup and view all the answers

Which of these factors is most likely to cause dysbiosis of the skin microbiota?

Environmental factors. Signup and view all the answers

How do bacteria achieve directional movement using their flagella?

Rotating the flagella either clockwise or counterclockwise Signup and view all the answers

What is the protein subunit that makes up fimbriae (pili)?

Pilins Signup and view all the answers

What structure is immediately external to a bacterial cell's cytoplasmic membrane?

Cell wall/outer membrane. Signup and view all the answers

During DNA replication, what is the primary function of topoisomerases?

To unwind and manage DNA supercoiling. Signup and view all the answers

Which movement pattern is typically associated with clockwise rotation of a bacterial flagellum?

Change in direction Signup and view all the answers

How is bacterial DNA characterized structurally?

Double-stranded and circular. Signup and view all the answers

Which enzyme is directly responsible for initiating the start of DNA replication?

Primase. Signup and view all the answers

What makes bacterial cell wall synthesis a unique target for antibiotic action?

Cell wall synthesis. Signup and view all the answers

During DNA replication in bacteria, in what manner are new strands of DNA synthesized?

Semiconservatively. Signup and view all the answers

What structural characteristic is typically associated with acid-fast bacteria?

A complex, lipid-rich structure. Signup and view all the answers

During Gram staining, what is the outcome for Gram-negative bacteria?

Crystal violet washes away, allowing a counter stain to be visible. Signup and view all the answers

Which specific component is typically found within the tetrapeptide of Gram-positive bacteria?

D-amino acid Signup and view all the answers

Which of the following bacteria is typically visualized as purple after Gram staining?

Staphylococci Signup and view all the answers

What are the primary influences on the composition of the intestinal microbiota in infants?

Mode of delivery and infant feeding method Signup and view all the answers

Which vitamin is NOT biosynthesized by the intestinal microbiota?

Vitamin D Signup and view all the answers

What typically characterizes the intestinal microbiota of infants?

Low stability and low diversity Signup and view all the answers

How is permanent colonization of microbes differentiated from transient colonization?

Duration of microbial presence Signup and view all the answers

Study Notes

Bacterial Cell Structure Quiz - Study Notes

Question 1: The primary structural difference between Gram-positive and Gram-negative bacteria is the thickness of the cell wall.
Question 2: Di-amino pimelic acid (DAP) is essential for cross-linking peptidoglycan chains.
Question 3: Enzymatic conversion is the process by which NAG is converted to NAM in bacterial cells.
Question 4: In Gram-negative bacteria, an amino acid bridge is formed for peptidoglycan cross-linking.
Question 5: Both D- and L-amino acids are found in the peptidoglycan tetrapeptide.
Question 6: Counterclockwise and clockwise rotation of flagella is responsible for directional movement in bacteria.
Question 7: Fimbriae (pili) are primarily composed of the protein pilin.
Question 8: Clockwise rotation of flagella in bacteria causes a change of direction in their movement.
Question 9: Fimbriae facilitate adherence to host tissues.
Question 10: One role of fimbriae tips is binding to specific sugars on host cells.
Question 11: Gram-positive bacteria typically have a significantly higher number of peptidoglycan layers (around 40) compared to Gram-negative bacteria (2-3 layers).
Question 12: Mycobacteria have a complex, lipid-rich cell wall structure, which confers acid-fastness.
Question 13: In Gram-negative bacteria during Gram staining, crystal violet is washed away, revealing the red counterstain.
Question 14: The D-amino acid component is found in the tetrapeptide of Gram-positive bacteria.
Question 15: Staphylococci are typically visualized as purple when Gram-stained.
Question 16: Factors influencing infant intestinal microbiota composition include mode of delivery, infant feeding method, birth weight/height, season of birth, and geographical location/parent's health.
Question 17: Vitamin D is not biosynthesized by intestinal microbiota.
Question 18: Infant intestinal microbiota is characterized by low stability and high diversity.
Question 19: Fermentation of polysaccharides by intestinal microbiota functions to provide energy sources for gut microbes.
Question 20: Dysbiosis in the gut microbiota is associated with increased risk of disease.
Question 21: The primary therapeutic application of fecal microbiota transplantation (FMT) is transferring healthy gut bacteria.
Question 22: Permanent colonization differs from transient colonization primarily due to the duration of the microbial presence within the body.
Question 23: Enhancing brain activity is NOT a function of intestinal microbiota.
Question 24: One main function of the skin microbiota is to maintain a healthy cutaneous barrier.
Question 25: Environmental factors can lead to dysbiosis of skin microbiota.
Question 26: The cell wall/outer membrane surrounds the cytoplasmic membrane of bacterial cells.
Question 27: Topoisomerases manage DNA supercoiling during DNA replication.
Question 28: Bacterial DNA is typically double-stranded and circular.
Question 29: Primase is primarily responsible for initiating DNA replication.
Question 30: Cell wall synthesis is a unique biochemical target for antibiotics in bacteria.
Question 31: New DNA strands are synthesized in a discontinuous manner during DNA replication.
Question 32: Virulence plasmids primarily help bacteria overcome stressful conditions.
Question 33: Bacteria have a haploid genome without histones.
Question 34: A nicking enzyme is required for rolling circle replication of DNA.
Question 35: Plasmids in bacteria are typically circular and extrachromosomal.
Question 36: Topoisomerase I is primarily involved in relaxing supercoiled circular DNA at the end of bacterial DNA replication.
Question 37: Bacterial DNA is typically single, circular, double-stranded and supercoiled.
Question 38: DNA-dependent DNA polymerase synthesizes a copy of the DNA during replication.
Question 39: Topoisomerases primarily support supercoiling and relaxation of DNA during bacterial DNA replication.

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Description

Test your knowledge on the structural differences between Gram-positive and Gram-negative bacteria, the roles of peptidoglycan, and the skin microbiota. This quiz covers essential concepts in microbiology related to bacterial cells, their components, and functions.