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
In electron microscopy, the smooth endoplasmic reticulum (SER) is distinguished from the rough endoplasmic reticulum (RER) by the absence of:
Answer: Ribosomes on its cytoplasmic surface
The RER bears ribosomes on its cytoplasmic face giving it a 'rough' appearance in EM, whereas the SER lacks ribosomes and appears smooth.
Peroxisomes detoxify harmful substances and are particularly abundant in hepatocytes. Their key enzyme for hydrogen peroxide decomposition is:
Answer: Catalase
Catalase converts the H₂O₂ generated by peroxisomal oxidases into water and oxygen, preventing oxidative cellular damage.
The centrosome, which serves as the main microtubule-organizing center in animal cells, consists of:
Answer: Two centrioles surrounded by pericentriolar material
The centrosome contains two centrioles (a mother and daughter) embedded within pericentriolar material (PCM) that nucleates microtubule polymerization.
Which microscopic finding best indicates active apoptosis in a histological section?
Answer: Cellular and nuclear fragmentation into membrane-bound apoptotic bodies
Apoptosis produces condensed chromatin, nuclear fragmentation (karyorrhexis), and blebbing of the membrane to form apoptotic bodies, without eliciting inflammation.
The glycocalyx coating the luminal surface of endothelial cells is composed primarily of:
Answer: Proteoglycans and glycoproteins
The glycocalyx is a carbohydrate-rich layer formed by proteoglycans, glycoproteins, and glycolipids anchored to the plasma membrane, mediating cell–cell and cell–matrix interactions.
Annulate lamellae are cytoplasmic organelles that structurally resemble:
Answer: Portions of the nuclear envelope with nuclear pore complexes
Annulate lamellae are stacks of membrane cisternae studded with pore complexes morphologically identical to nuclear pore complexes, likely derived from excess nuclear envelope material.
Which cytoskeletal element provides the mechanical basis for cilia and flagella movement?
Answer: Microtubules arranged in a 9+2 axoneme pattern
Cilia and flagella contain an axoneme of nine outer doublet microtubules surrounding a central pair, with dynein motor proteins generating the sliding force for movement.