phagocytosis

Question 1

what is phagocytosis? how does it work?

Answer 1

Phagocytosis is the uptake of large particles by cells. It progresses by a continuous membrane-zippering to form large phagosomes that are eventually engulfed by the cell.
in professional phagocytes, very large particles, degenerating cells, and microorganisms are internalized and sent to lysosomes via phagolysosomes.

Question 2

three paths to lysosomes for degradation

Answer 2

phagocytosis, endocytosis, and autophagy

Question 3

endocytosis

Answer 3

takes macromolecules from the extracellular fluid into endocytic vesicles, and then progressively through the endocytic pathway, from early to late endosomes, and then to lysosomes.

Question 4

pinocytosis

Answer 4

process of internalization, or “cell drinking”

Question 5

autophagy

Answer 5

by this process of “self-eating, old and worn out parts of cells are sequestered and sent to lysosomes for degradative “recycling”.

Question 6

lysosomes

Answer 6

cytoplasmic organelles bounded by a single membrane that contain a wide variety of hydrolytic enzymes

Question 7

pH of interior of lysosome. How is it maintained?

Answer 7

about 5, maintained by an ATP-dependent proton pump

Question 8

acid hydrolases

Answer 8

lysosomal enzymes that have optimal activities at pH of 5

Question 9

what size do lysosomes come in? what are their functions?

Answer 9

they are heterogenous in size and shape due to the wide variety of degradative function they perform. functions include breakdown of intra and extracellular debris, destruction of phagocytosed microorganisms and cells, and production of nutrients for the cell