Microbiology: Cell Structure and Function Flashcards
7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Microbiology: Cell Structure and Function flashcards as text
Endospores produced by Bacillus and Clostridium species are extraordinarily resistant to heat. Which component is MOST responsible for this resistance?
Answer: Dipicolinic acid chelated with calcium ions
Dipicolinic acid (DPA) complexed with calcium ions replaces water in the spore core and stabilizes proteins and DNA against heat denaturation.
Which eukaryotic cell structure is thought to have originated from an ancestral proteobacterium based on endosymbiotic theory?
Answer: Mitochondrion
Mitochondria are believed to have evolved from an alpha-proteobacterial endosymbiont, supported by evidence such as their own circular DNA, 70S ribosomes, and binary fission-like replication.
What distinguishes S-layer proteins from other bacterial surface structures?
Answer: They form a two-dimensional crystalline array covering the cell surface
S-layers are paracrystalline protein or glycoprotein arrays that self-assemble into a regular 2D lattice over the entire cell surface of many bacteria and archaea.
A bacterium lacking a functional sec (secretion) pathway would MOST likely fail to:
Answer: Translocate proteins across or into the cytoplasmic membrane
The Sec pathway is the primary general secretion system responsible for translocating unfolded proteins across the cytoplasmic membrane to the periplasm or cell surface.
Teichoic acids are a defining component of which type of bacterial cell wall?
Answer: Gram-positive peptidoglycan layer
Teichoic acids are anionic polymers (wall teichoic acids and lipoteichoic acids) embedded in the thick peptidoglycan of gram-positive bacteria, contributing to surface charge and ion regulation.
How does the periplasm of gram-negative bacteria differ from the cytoplasm?
Answer: It is a gel-like space between the inner and outer membranes containing degradative enzymes and binding proteins
The periplasm is an aqueous compartment between the inner and outer membranes that contains a variety of enzymes (proteases, nucleases), binding proteins for nutrient uptake, and chemoreceptors.
Which of the following structures is used by bacteria to transfer DNA during conjugation?
Answer: Sex pilus (F-pilus)
The sex pilus (encoded by the F plasmid) connects donor and recipient cells during conjugation, retracting to bring them together so that DNA can be transferred.