Mol Lecture #33 (a little short)

Question 1

Osmosis

Passive Transport

Answer 1

• Diffusion of water (solvent) across a semi-permeable membrane.
• Although water is somewhat polar its small enough to cross biological membranes
• Sucrose (for example) cannot go across the membrane, water is going to go towards the area where there is the highest sucrose concentration

Question 2

Tonicity

Answer 2

• Effects of water in the solution is called tonicity.
• describes concentration of a solution in the extracellular environment.

Question 3

Hypotonic conditions

Answer 3

• extracellular env. Has lower concentrations than inside the cell

Question 4

Hypertonic:

Answer 4

extracellular env. Has a higher concentration compared to the inside of the cell.

Question 5

Isotonic:

Answer 5

• extracellular env. Has an equal concentration (of the solute) in comparison to the cell.
• no net movement of water via osmosis

Question 6

Facilitated diffusion (Passive Transport)

Answer 6

• facilitated diffusion by transmembrane proteins
• Channels

Question 7

Channels

Answer 7

• proteins with a hydrophilic channel, that allow water, ions, molecules to pass through the membrane.
  –> Specific, but allows many iterations to pass at once. (ex. aquaporin)

Question 8

Gated channels (Passive Transport)

Answer 8

• Channels that can open and close (ex. K+ voltage gated channel- potassium can go down its concentration gradient)
• Only open under certain conditions

Question 9

© Carrier Protein (Passive Transport)

Answer 9

• Key: Undergoes a conformational shift to deliver the cargo (driven by the concentration gradient)
• Key: can only bind one or a few moelcules/ions to transport at a time.

Question 10

Active Transport

Overview

Answer 10

• When we want to move molecules or ions against their concentration gradient
• Move something from an area of low concentration to an area of high concentration.
• Requires input of energy →Primary and → secondary (Both refer to how energy is put in.)