AP Bio 7.5 Endocytosis and Exocytosis

Hypercholesterolemia

- Low density lipoproteins are particles that cholesterol travels in - LDL binds to LDL receptors on the plasma membrane and then enter the cell by endocytosis. - with this disease there is a high level of cholesterol in the blood because LDL receptor proteins are defective or missing.

What are the three types of Endocytosis?

- phagocytosis - pinocytosis - receptor-mediated endocytosis

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells. Then food inside vacuole gets digested by a lysosome. "cellular eating"

Pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes. Release contents to surrounding tissues. "Cellular drinking"

Endergonic

Endothermic

Exergonic: spontaneous, releases energy (so no energy is left), respiration, is negative Endergonic: non spontaneous, absorbs energy, photosynthesis, is positive (so needs energy)

Exergonic: spontaneous, releases energy (so no energy is left), respiration, is negative Endergonic: non spontaneous, absorbs

How do human cells take in cholesterol for membrane synthesis and the synthesis of other steroids?

Receptor mediated endocytosis

Receptor-mediated endocytosis

The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.

Exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

Exergonic

exothermic

How do large molecules cross the membrane?

in bulk via vesicles, requires energy

Endocytosis

process by which a cell takes material into the cell via formation of a vesicle from the plasma membrane (the membrane sinks inward to form a pocket, then pinches, making a vesicle that contains material that had been outside of the cell).