Cellular Structures Flashcards
7 cards from real Histology Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Cellular Structures flashcards as text
Gap junctions allow direct cytoplasmic communication between adjacent cells through protein channels called:
Answer: Connexons
Connexons (hemichannels) are formed by six connexin proteins and dock with connexons on neighboring cells to create gap junctions that pass ions and small molecules.
In a transmission electron micrograph, the outer membrane of the nuclear envelope is continuous with the:
Answer: Rough endoplasmic reticulum
The outer nuclear membrane is continuous with the RER membrane system and also bears ribosomes, integrating nuclear protein import with the secretory pathway.
Multivesicular bodies (MVBs) are late endosomes that fuse with lysosomes and are characterized ultrastructurally by:
Answer: A single membrane enclosing multiple internal vesicles
MVBs are bounded by a single limiting membrane enclosing intraluminal vesicles (ILVs) formed by inward budding of the endosomal membrane.
Which staining technique is most useful for demonstrating the Golgi apparatus in tissue sections using light microscopy?
Answer: Silver impregnation (osmium or silver nitrate)
The Golgi apparatus is classically demonstrated with osmium or silver impregnation methods, which blacken its lipid-rich membranes; it is not reliably visible by H&E alone.
The nucleolus is the site of synthesis and assembly of:
Answer: Ribosomal RNA and pre-ribosomal subunits
The nucleolus transcribes rRNA genes (rDNA) and assembles rRNA with ribosomal proteins to form pre-ribosomal subunits exported to the cytoplasm.
Intermediate filaments differ from actin and microtubules in that they:
Answer: Show no inherent polarity and are highly stable under most physiological conditions
Intermediate filaments are non-polar, rope-like polymers with greater mechanical stability and slower turnover than actin filaments or microtubules.
Which feature of the plasma membrane is critical for maintaining lipid raft microdomains that concentrate signaling molecules?
Answer: Enrichment of sphingolipids and cholesterol forming tightly packed gel-like regions
Lipid rafts form when sphingolipids and cholesterol pack together tightly, creating ordered membrane microdomains that cluster GPI-anchored proteins and signaling receptors.