AP BIOLOGY

Detailed explanation-1: -It is the activation of the execution caspases that begins this phase of apoptosis. Execution caspases activate cytoplasmic endonuclease, which degrades nuclear material, and proteases that degrade the nuclear and cytoskeletal proteins.

Detailed explanation-2: -The degradation of cellular content is initiated in apoptotic cells and completed within engulfing cells. In apoptotic cells, caspase-mediated proteolysis cleaves protein substrates into fragments; nuclear DNA is partially degraded into nucleosomal units; and autophagy potentially contributes to apoptotic-cell removal.

Detailed explanation-3: -To illustrate these apoptosis events and how to detect them, Bio-Rad has created a pathway which divides apoptosis into four stages: induction, early phase, mid phase and late phase (Figure 1).

Detailed explanation-4: -Apoptosis is mediated by proteolytic enzymes called caspases, which trigger cell death by cleaving specific proteins in the cytoplasm and nucleus. Caspases exist in all cells as inactive precursors, or procaspases, which are usually activated by cleavage by other caspases, producing a proteolytic caspase cascade.