Active Transport

Active Transport • Requires energy

– in the form of ATP (useful cellular energy)

– movement against the concentration gradient

What does

“against” the

concentration

gradient

mean??

2 methods of Active Transport 1. Pumps

2. Change in the cell membrane (aka vesicular transport)

Active Transport Pumps:

• Requires a protein channel called a “pump”

• Requires ATP

• Movement from low concentration to high concentration

– moving up the hill hi concentration

low concentration

• Works in the opposite direction of facilitated diffusion.

• Energy (by way of ATP) forces materials through a protein in the membrane against concentration gradient.

Active transport pump

You do not need to

understand HOW

this works…just

WHY a cell would

require energy in

order to do this.

Why Pump?

• Nerve cells need a difference in ions (charge) on either side of the membrane so they can fire.

Which way would the potassium ions (K+)

tend to go? (Would they go into the cell or out of the

cell? How do you know?)

• A.K.A. “Vesicular Transport” - Used for large substances or large amounts of substances.

• Two types:

– Endocytosis:

• IN to the cell (ENTER)

– Exocytosis:

• OUT of the cell (EXIT)

Change in cell membrane (2nd type of active transport process)

Change in cell membrane (2nd type of active transport process)

• Endocytosis (IN)

– Takes in (engulfs) large material

• Cell membrane moves in until it encapsulates material, becoming a vesicle.

Endocytosis: (IN)

–Two types:

•Phagocytosis

•Pinocytosis

Phagocytosis:

• “Cell Eating”

– Pseudopods engulf material with extensions of the cell membrane.

– E.g. White blood cell taking in foreign material for destruction.

– E.g. Amoeba engulfing a diatom

Phagocytosis:

Pinocytosis:

• “Cell Drinking”

–Membrane wraps around a big drop of solution (solute & solvent) and pulls it in.

Pinocytosis:

Change in cell membrane (2nd type of active transport process)

• Exocytosis (OUT)

– Vesicle that gets rid of large material

• Vesicle fuses with cell membrane, releasing contents to outside of cell.

– E.g. Waste

– E.g. Digestive enzymes

A goblet cell procedures mucin

which when dissolved in water

is the main component of

mucus. What is the purpose of

mucus?

RNA

Rough ER

Golgi apparatus

Plasma membrane

Exocytosis: (OUT)

Protein in vesicle

Figure 7.14 The formation and functions of lysosomes (Layer 1)

Figure 7.14 The formation and functions of lysosomes (Layer 2)

Figure 7.14 The formation and functions of lysosomes (Layer 3)

Often

used to

recycle

cell parts

(do NOT need

to know for

test)