Module 4.2 - Active Transport

Active Transport

It is when particles move against a concentration gradient from low to high concentration.

Active Transport

This type of transport requires energy.

ATP Hydrolysis

Energy is supplied through blank.

Transport protein

The terminal phosphate of ATP is transferred to the blank.

Transport protein

This induces the protein to change its shape so the solute can pass through.

Carrier Proteins

Move solutes against their concentration gradients, not channel proteins.

Potassium ions, 20-50

In animal cells, blank concentration is blank times greater inside the cell.

Sodium ions, 10

In animal cells, blank are blank times more concentration outside a cell.

Three sodium ions, two potassium ions

The pump does not translocate sodium and potassium one for one, but pumps blank out of every blank it pumps into the cell.

Negative

Typically, the inside of the cell is blank relative to the outside.

K+ leak channels

Help maintain the negative inside of the cell.

Exocytosis

The cell secretes certain molecules by the fusion of vesicles with the plasma membrane and extruding its contents to the surrounding environment.

Endocytosis

It is the ingestion of material by the cells.

Phagocytosis, pinocytosis, receptor-mediated endocytosis

Three types of endocytosis

Cellular eating

Phagocytosis means:

An amoeba engulfing a paramecium

Example of phagocytosis

Cellular drinking

Pinocytosis means:

Phagocytosis

1. An area of plasma membrane forms a pocket and engulfs a particle.

2. The particle is packaged in a membranous sac called the food vacuole.

3. The food vacuole detaches from the cell surface and moves to fuse with the lysosome.

4. Contents are digested by the lysosomal enzymes.

Pinocytosis

1. Small areas of the cell membrane folds inward to make tiny pockets.

2. Droplets of extracellular fluid is “gulped” into tiny pockets until it is pinched off, creating small vesicles.

3. Lysosomes fuse with the vesicles to digest contents.

Receptor-mediated Endocytosis

1. Proteins with receptor sites in the plasma membrane is exposed to the extracellular fluid.

2. Specific solutes (ligands) bind to the receptors, which stimulates invagination of coated pits.

3. Each coated pit forms a vesicle that contains the ligand.

4. Vesicle fuses with lysosomes, which breaks down the large solutes.