The Biology Project: Cell Biology

The Biology Project > Cell Biology > Cell Membranes > Problem Set

Cell Membranes Problem Set

Problem 16: Membrane flow


Cell membrane components are synthesized in the endoplasmic reticulum, transported as vesicles to the Golgi apparatus where they are modified, and then are transported to the cell surface where they deliver their contents to the cells exterior and become a part of the cell membrane in a process called ____________. The reverse of this process, bringing nutrient containing particles from out side to the inside of the cell is called _________.


exocytosis; endocytosis

The membranes of the cell are dynamic, constantly being formed, recycled, and degraded. Membranes flow between cellular compartments and the cell surface, and also are endocytosed or taken up from the cell surface. This process results in both cell membranes and extra-cellular materials being taken up by cells.

The materials ingested by endocytosis are frequently added to lysosomes, where the materials are degraded. The membrane lipids, proteins, and carbohydrates are also degraded in the lysosome. If one or more of the lysosomal enzymes are defective, then cell membrane material may build up causing a lysosomal storage disease.

In Tay Sach's disease, the enzyme hexosaminidase A is defective, and carbohydrate containing glycolipids can't be degraded. The build up of lysosomal glycolipids leads to serious neurological abnormalities and death.

B. active transport; passive transport
C. simple diffusion; facilitated diffusion
D. osmosis; diffusion
Tutorial | The end

The Biology Project > Cell Biology > Cell Membranes > Problem Set
All contents copyright © 2002-04. All rights reserved.

The Biology Project Cell Biology