1. Objective
Students will be able to define the terms bulk transport, endocytosis, and exocytosis in order to describe how molecules gets into and out of the cell during active transport.

2. Cell Membrane Pumps And Bulk Transport
ACTIVE TRANSPORT
Cell Membrane Pumps
And
Bulk Transport

3. Active Transport: Why do cells need active transport?
The movement of molecules across the cell membrane from an area of lower concentration to an area of higher concentration
Requires energy (ATP)
Goes up or against the concentration gradient
Why do cells need active transport?
Materials must be moved from an area of lower concentration to an area of higher concentration.
Materials are too large to pass through the cell membrane

4. Active Transport
3 types
Cell membrane pumps
Endocytosis
Exocytosis

5. Active Transport: Cell Membrane Pumps
a.k.a. carrier proteins
Proteins are used in both passive and active transport

6. Active Transport: Cell Membrane Pumps
Example of one cell membrane pump:
Sodium-potassium pump
This protein transports Na+ ions and K+ ions up their concentration gradients. (From low to high concentration.)
WHY???
To function normally, many types of animal cells must have a higher concentration of Na+ ions outside the cell and a higher concentration of K+ ions inside the cell.

7. Sodium-Potassium Pump
Click to see the animation.

8. Active Transport: Bulk Transport
Large molecules, food, and other substances are packaged in membrane- bound sacs called vesicles and moved across the membrane.

9. Active Transport: Bulk Transport - Endocytosis
Materials are brought INTO the cell
the cell membrane folds into a pouch that encloses the particles.
The pouch pinches off inside the cell to form a vesicle (membrane-wrapped bubbles).
The vesicle can fuse with other organelles (Lysosomes) OR release its contents into the Cytoplasm.

10. Active Transport: Bulk Transport - Endocytosis

11. Active Transport: Bulk Transport - Endocytosis
Two types of endocytosis:
Pinocytosis - “cell drinking.”
Solutes or fluids outside the cell membrane can be brought into the cytoplasm by pinocytosis.
Phagocytosis - “cell eating”.
Food particles or other cells are ingested
White blood cells do this when they destroy invading bacteria cells

12. Active Transport: Bulk Transport - Exocytosis
Materials are exported OUT of the cell
Products made in the cell are packaged in golgi vesicles, which then fuse with the cell membrane and materials are secreted OUT of the cell.

13. Active Transport: Bulk Transport - Exocytosis