Exam 1: Proteins/Transport/Diffusion

Question 1

What is used as the main gateway to get things into/out of the cell?

Answer 1

Proteins

Question 2

How do gasses pass into the cell?

Answer 2

Simple diffusion

Question 3

When O2 goes into a cell what happens?

Answer 3

The body takes the oxygen and via another system (Kreb’s cycle) CO2 is produced as a byproduct and leaves the cell without any problem

Question 4

Are gases water or lipid-soluble?

Answer 4

Lipid soluble; this is why it makes it so easy for them to pass over cell membranes

Question 5

How do we transport electrolytes across a cell membrane?

Answer 5

Via opening channels

Question 6

Why do electrolytes need extra help getting across a cell membrane?

Answer 6

Because they are charged molecules

Question 7

What is the downfall of using channels to transport electrolytes across the cell wall?

Answer 7

Water can sneak its way into the cell and cause the cell to swell if too much water is allowed through

Question 8

How does water get in/out of the cell?

Answer 8

Via water specific channels called aquaporins (AQP) and leaking in through electrolyte channels.

Question 9

How does the body regulate the amount of water that can come into and out of cells?

Answer 9

By regulating the amount of AQPs

Question 10

If something doesn’t require proteins to transport across the cell membrane, what type of transport is this?

Answer 10

Simple diffusion

Question 11

When you want to get a compound across the cell quickly or in a place they don’t naturally go, what is needed to accomplish this task?

Answer 11

Energy

Question 12

T/F Using energy slows down the rate at which things go across the cell

Answer 12

False; energy makes things transport against a gradient much faster

Question 13

Explain the Sodium/Potassium Pump

Answer 13

An enzyme metabolizes ATP and ribs a phosphate group off to give ADP, which gives the cell energy. The energy is liberated and helps to move 3 sodium outside of the cell and 2 potassium inside of the cell. It takes 1 molecule of ATP to move 5 ions across a membrane into areas they do not want to go into.

Question 14

T/F All excitable cells will have a Na/K/ATP pump

Answer 14

True

Question 15

What is the single most energy-requiring process in the body?

Answer 15

Neurons sending action potentials and messages to the body

Question 16

Why is the Na/K/ATP pump considered primary active transport?

Answer 16

Because it uses ATP directly and metabolizes it directly

Question 17

Explain the calcium channel and how calcium goes into/out of the cell.

Answer 17

We want to keep calcium concentrations low inside of the cell so sometimes we must push calcium outside of the cell to prevent the cell from turning itself on. (When calcium inside of the cell is low, it is turned off). We have specific pumps to take calcium and put it in a place where it does not want to go which is outside of the cell. This also requires ATP and thus is an example of primary active transport.

Question 18

What are 3 examples of primary active transport?

Answer 18

1. Sodium potassium pump
2. Calcium pump
3. Acid proton pump (stomach cells secreting acid)

Question 19

What is secondary active transport?

Answer 19

Secondary active transport is transport that requries energy but does not require ATP directly

Question 20

What are 2 examples of secondary active transport?

Answer 20

1. Sodium Calcium Exchanger (NCX)
2. Sodium Glucose Pumps (SGLT)

Question 21

When do we use the sodium calcium exchanger?

Answer 21

When the Calcium/ATPase pumps is not working efficiently; when there is too much calcium inside of the cells and we want to get it out faster

Question 22

How does the sodium calcium exchanger work?

Answer 22

Sodium and calcium are exchanged for one another. 1 calcium will be moved to the outside of the cell in exchange for 3 sodium molecules coming into the cell. This relies on an electrochemical gradient for sodium since sodium wants to come into the cell so badly.
The exchanger will take energy that is generated from the 3 sodium entering and harness it to function like a turnstile and push calcium out of the cell

Question 23

Does the sodium-calcium exchanger burn ATP directly?

Answer 23

No. It relies on another process to burn the ATP.

Question 24

Name a place where you would want to remove calcium quickly from the cells.

Answer 24

In the muscles

Question 25

Where is the sodium/glucose pump found?

Answer 25

Kidneys

Question 26

How does the sodium/glucose (SGLT) pump work?

Answer 26

1 or 2 sodium will come into the cell alongside glucose. Glucose is needed in the cell faster and thus enters with sodium. By coupling the two together, speeds up the movement and helps the kidney so that glucose isn't dumped into the urine.

Question 27

What is an example of facilitated diffusion?

Answer 27

Glucose transport across the cell with the GLUT transporter

Question 28

How does glucose move into the cell via GLUT?

Answer 28

Glucose binds to the receptor and there is a conformational change that allows the glucose to be brought into the cells and released from the receptor. Since this process does not require energy, it is thought of as facilitated diffusion. There is still something needed to help get the glucose into the cell but no energy is required.

Question 29

How is the bulk of glucose transported into the cell?

Answer 29

Via GLUT transporters

Question 30

T/F GLUT-4 is insulin dependent?

Answer 30

True

Question 31

What is the most widely known GLUT transporter?

Answer 31

GLUT-4

Question 31

What occurs when there is more insulin present?

Answer 31

When more insulin is present, there are more GLUT receptors moved to the cell wall to transport more glucose across the cell wall to get the cell energy ASAP

Question 32

How many ions are involved with the Na/K pump?

Answer 32

5 ions in total are going in opposite directions

Question 33

Where does sodium come from that is used in the Na/K pump?

Answer 33

Extra sodium comes from the secondary transport processes like the sodium calcium exchangerW

Question 34

What is Vmax in relation to facilitated diffusion?

Answer 34

Vmax is the max speed where conformational changes can occur; this is the amount where the cell is transporting as fast as it can and it can't do anything more but add more receptors into the cell wall to help with transporting Once you hit Vmax, you can't do it any faster

Question 35

T/F Simple diffusion has a Vmax

Answer 35

False; there is not a Vmax with simple diffusion because you are not relying on a conformational change with the receptor

Question 36

Name examples of things that will increase/decrease the diffusion rate?

Answer 36

1. Concentration of ions inside vs. outside of the cell 2. Membrane solubility 3. Size of particles 4. Size of pores 5. Number of pores for travel 6. Kinetic movement 7. Physical pressure 8. Electrical charge 9. Chemical gradient 10. Membrane permeability

Question 37

Which direction does water want to move?

Answer 37

Down its concentration gradient

Question 38

What does it mean when you move "down" and "up" a concentration gradient?

Answer 38

Down = moving from an area of high concentration to low concentration Up = moving from an area of low concentration to high concentration

Question 39

Explain what happens when you have a U-shaped test tube with a semipermeable membrane and you have pure water on one side with solutes on the other side.

Answer 39

Water will move across the membrane and into the area with a lower concentration of water, which is the area with the higher concentration of solutes. *Remember, water wants to move to areas of low concentration; the solutes are causing water to be in a state of "lower" concentration because they are essentially diluting the water*

Question 40

What is osmotic pressure?

Answer 40

The physical pressure required to prevent osmosis from occurring through a semipermeable membrane

Question 41

Will water continue moving across a semipermeable membrane until the concentrations are equal?

Answer 41

In a perfect world, yes. However, water will stop moving at the point where the osmotic pressure is created and does not allow the water to flow freely anymore.