Transport methods, osmotic pressure

Question 1

What is co-transport?

Answer 1

• a mechanism to get certain molecules up against its concentration gradient while having another molecule move down its concentration gradient.

Question 2

What factors affect the net rate of diffusion?

Answer 2

• concentration gradient (difference across membranes)
• osmotic /oncotic pressure
• membrane electrical potential
• hydrostatic pressure (fluid pressure)

Question 3

What is osmotic pressure?

Answer 3

• exact amount of pressure required to stop osmosis (water diffusion)

Question 4

What is oncotic pressure?

Answer 4

• osmotic pressure caused by protein

Question 5

What is hydrostatic pressure?

Answer 5

• pressure of fluid inside a space

- force exerted by a column of fluid against the wall of the container

Question 6

What diffuses through the membrane?

Answer 6

Non-polar molecules such as oxygen, CO2, nitrogen, alcohol, water and other lipid substances

Question 7

What is active transport?

Answer 7

• uses ATP to transport a molecule against its concentration gradient through carrier protein.

Question 8

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

Answer 8

• Primary active transport: energy used to transport a molecule against its concentration gradient is directly due to ATP breakdown.
• Secondary: energy used to transport a molecule against its concentration gradient is due to movement of molecule down/against its concentration gradient. Can be co/counter transport.

Question 9

What determines the resting membrane potential of the cell?

Answer 9

• Na/KATpase pump (pump 3 Na out and 2 K in)
• N/K leak channels (constantly leaks more K out and less Na in)
• negatively charged proteins inside the cell.

Question 10

What are the steps of the action potential?

Answer 10

1. resting membrane potential
2. increase in Na inside cells causes depolarization to reach threshold.
3. threshold reached, causes more voltage gated Na channels to open and Na rushes in, causing complete depolarization/action potential in the cell.
4. Once action potential reached about 30 mV, triggers Na channels to close and voltage gated K channels to open. This causes more K to go out of the cell and resulting in repolarization and then back to its resting membrane potential.