Lecture #6 - Compartments, connectivity, & membrane transport

voltage-gated channel

open or close depending on an electrical change in the membrane

ligand-gated channel

open or close depending on the binding of a ligand (hormone)

mechanically-gated channels

open or close depending on physical stimuli like stretching of the membrane

True or False: Active transport goes with the concentration gradient.

False: Active transport goes against the concentration gradient.

Where are most active transports at?

through transporters (pumps)

List the 3 types of carriers or transporters.

1. Uniporter: 1 molecule one direction

2. Symport: 2 molecules in one direction

3. Antiport: 2 molecules in different directions

What is the difference between primary active transport and secondary active transport?

• Primary active transport → energy derived directly from ATP

• Secondary active transport → derived secondarily from energy that has been used in the form of a concentration gradient

Can you have a secondary active transporter without a primary active transporter?

No → primary AT generates concentration gradient needed to drive secondary AT

What is this image an example of?

Passive transport (down its concentration gradient)

What is another form of active transport?

vesicular transport →

What is exocytosis?

Intracellular vesicles fuse with the plasma membrane and leave the cell

What are two forms of endocytosis?

1. Phagocytosis: engulfing larger molecules (macrophages, neutrophils)

2. Pinocytosis: engulfing smaller molecules

3. Receptor-mediated endocytosis: specific

True or False: Symporters use energy to transport chemicals across a membrane

True

Define Transepithelial transport.

the movement of chemicals across an epithelium

• ex: intestine, kidney, glands

What transepithelial transport happens between the epithelial?

paracellular

What transepithelial transport happens through both membranes of the epithelium?

transcellular

Why are tight junctions important?

Tight junctions act as security to make sure molecules and ions do not enter the cell or leave the cell through epithelium cells.

What is the importance of the Na+/K+ pump?

establishing different electrical and concentration gradients outside and inside the cell (production of ATP)

1. anions

2. nutrients

3. water

4. other solutes in the lumen

The Na+/K+ ATPase creates a ____________. This is used as a _________ type of _________ transport.

• concentration gradient

• secondary

• active transport

Draw out the Na+/K+ ATPase pump.

True or False: Active transports go with the concentration gradient.

False: Active transports go against the concentration gradient.