Modern Biology Chapter 5 Active Transport

Describe how a cell produces and releases proteins.

Proteins are made on ribosomes and packaged into vesicles by the Golgi apparatus. The vesicles move to the cell membrane and fuse with it, releasing the proteins from the cell through exocytosis.

Define vesicle

A vesicle is a membrane-bound organelle that pinches off from the cell membrane during endocytosis or fuses with the cell membrane during exocytosis.

Define active transport

Active transport is the movement of materials across a membrane from an area of lower concentration to an area of higher concentration.

Define endocytosis

Endocytosis is the process by which cells ingest external fluid, macromolecules, and large particles.

Define phagocytosis

Phagocytosis is a type of endocytosis in which cells ingest large particles or whole cells.

Why is it important that ions being transported across a cell membrane be shielded from the interior of the lipid bilayer?

The interior of the lipid bilayer is nonpolar and therefore would repel ions, which are attracted to polar environments.

Why is the sodium-potassium transport mechanism called a "pump"?

The mechanism uses energy to move (pump) Na+ and K+ up their concentration gradients.

Explain how a phagocyte destroys bacteria.

The phagocyte forms a pouch in its cell membrane and engulfs bacteria in the pouch. It then pinches off the pouch to form a vesicle. Lysosomes fuse with the vesicle, and lysosomal enzymes destroy the bacteria it contains.

The sodium-potassium pump transports a. Na+ out of the cell and K+ into the cell. b. Na+ and K+ in both directions across the cell membrane. c. K+ out of the cell and Na+ into the cell. d. Na+ during some cycles and K+ during other cycles.

a. Na+ out of the cell and K+ into the cell.

Facilitated-diffusion carrier proteins and cell-membrane pumps both a. require an input of energy. b. are specific for the kinds of substances they transport. c. transport substances up their concentration gradients. d. carry out active transport.

b. are specific for the kinds of substances they transport.

Pinocytosis involves the transport of a. large particles out of a cell. b. fluids into a cell. c. whole cells into another cell. d. lysosomes out of a cell.

b. fluids into a cell.

The energy needed to power the sodium-potassium pump is provided by the a. binding of ATP to the pump. b. transport of ATP by the pump. c. removal of a phosphate group from ATP. d. formation of ATP.

c. removal of a phosphate group from ATP.

Exocytosis is a a. type of passive transport. b. mechanism by which cells ingest other cells. c. transport process in which vesicles are formed from pouches in the cell membrane. d. way for cells to release large molecules, such as proteins.

d. way for cells to release large molecules, such as proteins.