active transport (1.2)

What is the primary mode of active transport?

through protein pumps

What is active transport? Why is it needed?

• movement across membrane with an ENERGY COST (ATP IS USED)

Purpose:

• energy is needed b/c particles move AGAINST a concentration gradient

What do protein pumps do?

• pump specific compounds IN or OUT of the cell

what membrane transport protein do protein pumps require?

pumps (obviously)

What is a sodium potassium pump? How does it work? (what goes in and out) and the purpose

Na moves OUT of the cell

K+ moves INTO the cell

How it works:

1) Three Na⁺ ions bind to the pump inside the cell.

2) ATP provides energy, changing the pump's shape.

3) The pump releases the 3 Na⁺ ions outside.

4) Two K⁺ ions bind to the pump outside the cell.

5) The pump returns to its original shape and releases the 2 K⁺ ions inside.

purpose: used by nerve cells to move a nerve signal

What is a proton pump? How does it work? What organelles (2) uses it?

What: moves hydrogen ions across a membrane using energy from ATP

How it works:

1) H⁺ ions bind to the pump.

2) ATP provides energy to change the pump's shape.

3) The pump moves H⁺ ions across the membrane, against their concentration gradient.

5) The ions are released on the other side.

Organelles: used in MITOCHRONDRIA & CHLOROPLASTS

What is vesicle transport for? what does this cause to the membrane?

• molecules that are too large to fit through the phospholipid bilayer or a protein carrier/channel must enter a cell through a vesicle instead

involves: some rearrangement of the cell membrane

what are 2 examples of molecules that would need vesicle transport?

• proteins

• polysaccharides

(very large molecules)

What are the 2 types of vesicle transport?

1) Endocytosis → IN the cell

2) Exocytosis -→ OUT of the cell

How does endocytosis work? what are the 3 types?

How it works:

• involves the pinching of a portion of the cell membrane around the material to be transported into the cell

• pinched in portion eventually breaks off from the cell membrane and forms a vesicle in the cytoplasm

3 types:

1) phagocytosis → “cell eating” —vesicle called PHAGOSOME

2) pinocytosis → “cell drinking” — dissolved stuff + extracellular fluid

3) receptor mediated endocytosis (RME) → cell takes in specific substance that bind to receptors on its membrane

What happens in phagocytosis? purpose + what kind of stuff goes in

• movement of very large particles into the cell’s interior

• large particles: bacteria, dying cell

**also virus

What happens in pinocytosis? what goes in?

• transport of liquids through vesicles

• small molecules dissolved in the extracellular fluid is taken in

What happens in receptor mediated endocytosis?

• (LIGAND) molecules bind to special receptor proteins located on the outside of the cell membrane

• once enough molecules have gathered in an area, cell membrane will transport these molecules into the cell

What is exocytosis used for? what organelle uses it for stuff? (4)

• exports very large molecules OUT of the cell (opposite of endocytosis)

• golgi bodies create many vesicles for the purpose of secreting hormones, digestive enzymes, proteins, polysaccharides