Q.32 The characteristic morphological change(s) in cells undergoing apoptosis is/are
(A) formation of blebs on cell surface
(B) swelling and bursting of cells
(C) collapse of the cytoskeleton
(D) condensation and fragmentation of nuclear chromatin
Correct Answer: A, C, D
Apoptosis features distinct morphological changes that distinguish it from necrosis, including cell surface blebs, cytoskeletal collapse, and nuclear chromatin alterations. These occur in a controlled manner without inflammation.
Option Analysis
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(A) Formation of blebs on cell surface: Correct. Blebbing arises from cytoskeletal reorganization and myosin activation, forming protrusions that lead to apoptotic bodies.
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(B) Swelling and bursting of cells: Incorrect. This describes necrosis, where cells swell, rupture, and trigger inflammation, unlike apoptosis’s shrinkage.
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(C) Collapse of the cytoskeleton: Correct. Caspases degrade actin and microtubules, causing cell rounding and bleb formation.
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(D) Condensation and fragmentation of nuclear chromatin: Correct. Chromatin aggregates peripherally (pyknosis), then fragments (karyorrhexis) due to endonucleases like CAD.
Apoptosis, or programmed cell death, triggers specific characteristic morphological changes in cells undergoing apoptosis to maintain tissue homeostasis without inflammation. These include cell shrinkage, plasma membrane blebbing, cytoskeleton collapse, and nuclear chromatin condensation and fragmentation.
Key Morphological Features
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Cell shrinkage with dense eosinophilic cytoplasm and packed organelles.
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Plasma membrane blebbing due to actomyosin ring formation, progressing to apoptotic bodies.
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Cytoskeleton collapse from caspase-mediated actin and microtubule breakdown.
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Nuclear changes: peripheral chromatin condensation (pyknosis), followed by fragmentation (karyorrhexis) into nucleosome-sized pieces.
Apoptosis vs. Necrosis
| Feature | Apoptosis | Necrosis |
|---|---|---|
| Cell size | Shrinkage | Swelling and bursting |
| Membrane | Blebs, intact until bodies | Rupture, content release |
| Cytoskeleton | Collapse | Vacuoles, no specific collapse |
| Nucleus | Chromatin condensation/fragmentation | Karyolysis |
| Inflammation | Absent | Present |
These characteristic morphological changes in cells undergoing apoptosis ensure orderly dismantling, vital for development, cancer suppression, and immune regulation. For CSIR NET aspirants, distinguishing them from necrotic changes is key in cell biology questions.
