Chapter 2 The Living Cell Part 3

Front 1

Active Transport

Back 1

-When substances use the energy in the bonds of ATP to move across the membrane.

Front 2

What substances use Active Transport?

Back 2

1. too large to move via protein channels.

2. Incapable of dissolving in lipid bilayer.

3. Substances that need to move "uphill" against their concentration or electrochemical gradient.
*Uses protein transporters
(pumps)
EX: Na+, K+, H+, Ca+2, I-, Cl-, and monosaccharides.

Front 3

Primary Active Transport

Back 3

1. Uses ATP
2. transport of substances against a concentration (or electrochemical) gradient. Preformed across the plasma membrane by a solute pump, directly using energy of ATP hydrolysis.
3. EX: Ions (Na, K, H, Ca2, and others)

Front 4

Secondary Active Transport

Back 4

1. Uses Ion concentration gradient maintained with ATP.
2. Cotransport (coupled transport) of two solutes across the membrane. Energy is supplied indirectly by the ion gradient created by primary active transport. Symporters move the transported substances in the same direction; antiporters move transported substances in opposite directions across the membrane.
3. EX: Movement of polar or charged solutes, e.g., Ca2, H (out of cells via antiporters).

Front 5

Vesicular Transport

Back 5

Is an active transport process.
1. Import materials from the extracellular space (endocytosis)
2. Export materials into the extracellular space (exocytosis)
3. Transcytosis which transports into, across, then out of the cell.
4. Vesicular (substance) trafficking which moves substances within the cell.

Front 6

Exocytosis

Back 6

1. Uses ATP

2.Secretion or ejection of substances from a cell. the substance is enclosed in a membranous vesicle, which fuses with the plasma membrane and ruptures, releasing the substance to the exterior.
3. EX: Secretion of neurotransmitters, hormones, mucus, etc.; ejection of cell wastes.

Front 7

Endocytosis:
Via clathrin-coated vesicles

Phagocytosis

Back 7

1. Uses ATP.
2. "Cell eating": A large external particle (proteins, bacteria, dead cell debris) is surrounded by a "seizing foot" and becomes enclosed in a vesicle (phagosome).
3. EX: In the human body, occurs primarily in protective phagocytes (some white blood cells and macrophages).

Front 8

Pinocytosis
(fluid-phase endocytosis)

Back 8

1. Uses ATP.
2. Plasma membrane sinks beneath an external fluid droplet containing small solutes. Membrane edges fuse, forming a fluid-filled vesicle.
3. EX: Occurs in most cells; important for taking in dissolved solutes by absorptive cells of the kidney and intestine.

Front 9

Receptor-mediated endocytosis

Back 9

1. Uses ATP.
2. Selective endocytosis and transcytosis. External substance binds to membrane receptors.
3. EX: Means of intake of some hormones, cholesterol, iron, and most macromolecules.

Front 10

Via caveolin-coated vesicles (caveolae)

Back 10

1. Uses ATP.
2. Selective endocytosis (and transcytosis). External substance binds to membrane receptors (often associated with lipid rafts).
3. Roles not fully known; proposed roles include cholesterol regulation and trafficking, and platforms for signal transduction.

Front 11

Intracellular vesicular trafficking

Via coatomer-coated vesicles

Back 11

1. Uses ATP.
2. Vesicles pinch off from organelles and travel to other organelles to deliver their cargo.
3. EX: Accounts for nearly all intracellular trafficking between certain organelles (endoplasmic reticulum and Golgi apparatus). Exceptions include vesicles budding from the trans face of the Golgi apparatus, which are clathrin-coated.