AP BIOLOGY

Detailed explanation-1: -The Fab portion of IgG or IgM binds to epitopes on the outer membrane of the gram-negative cell wall. This activates the complement pathway enabling the membrane attack complex (MAC) to insert through the outer membrane and cytoplasmic membrane causing the bacterium to lyse.

Detailed explanation-2: -The foreign microorganism, viruses, fungi, and damaged erythrocytes or nucleated cells can be lysed by MAC. The cytolytic mechanism is considered to be penetration the cell membrane, leading to uncontrolled influx of ions and water down the osmotic gradient, causing the cell to swell and ultimately burst.

Detailed explanation-3: -The complement membrane attack complex (MAC) is classically known as a cytolytic effector of innate and adaptive immunity that forms pores in the plasma membrane of pathogens or targeted cells, leading to osmolysis.

Detailed explanation-4: -MAC is generated through sequential assembly from the soluble complement proteins C5b, C6, C7, C8, and C9.

Detailed explanation-5: -The MAC forms trans–plasma membrane channels on the surface of pathogenic bacteria, causing cell lysis and death [34]. The bacteria are first identified and tagged by antibodies that attach to specific bacteria-surface carbohydrates. This response stimulates the complement cascade leading to generation of the MAC.