7

Question 1

What is the plasma membrane?
Which parts are polar and which parts are non polar?

Answer 1

-a phospholipid bi-layer
-heads of the lipids are polar and hydrophilic
-tails are non-polar and hydrophilic

Question 2

Is the plasma membrane permeable, semi permeable, or non permeable? What does this mean?

Answer 2

-semipermeable
-only certain molecules can pass without the assistance of a protein

Question 3

What influences a membrane’s fluidity?

Answer 3

Temperature. It must maintain its fluidity and The membrane must find a balance…

Question 4

What helps the plasma membrane in low temperatures? How so?

Answer 4

Unsaturated fats

The kinks prevent tight packing of lipids, so it doesn’t get too viscous (like cold honey)

Question 5

What helps the plasma membrane in high temperatures? How so?

Answer 5

-Saturated fats
-No kinks, so they tight packet and maintain viscosity (think warm honey)

Question 6

How does cholesterol play a role in the plasma membrane?
Where is it?

Answer 6

-It acts as a buffer of membrane fluidity
-it is packed between lipids in the bi-layer

Question 7

What are the three types of transports?

Answer 7

1. Passive transport
2. Active transport
3. Bulk transport

Question 8

Define passive transport and its properties

Answer 8

-No ATP required
-Diffusing down the concentration gradient
-diffusion and facilitated diffusion
-includes osmosis

Question 9

What is facilitated diffusion?

Answer 9

When a protein helps diffuse the solute (high to low)

Question 10

Define active transport and its properties

Answer 10

-It is when energy and a transport protein are required to move the solute against the concentration gradient (low to high)
-Requires ATP

Question 11

Define bulk transport and its properties

Answer 11

Vesicles moving large molecules like fatty acids (endo in, exo out)

Question 12

What can pass through the plasma membrane? How?

Answer 12

1. Small non-polar molecules which are hydrophobic (CO2, O2) through passive transport
2. Polar hydrophilic molecules can only pass with the help of a protein (active transport)
3. Ions can pass but also need help. They can’t do it alone

Question 13

What are the 7 types of transport proteins?

Answer 13

1. Channel proteins
2. Carrier proteins
3. Ion channels
4. Glycoproteins
5. Sodium potassium pump
6. Proton pump
7. Cotransport pump

Question 14

Define channel proteins and their properties

Answer 14

1. Extends through the membrane
2. It’s a channel
3. Accepts specific molecules and leads them into the cell

Question 15

Define carrier proteins and their properties

Answer 15

-It is also a channel, but it closes until it receives the molecule that wants to go in (imagine bringing food to your mouth)
-undergoes a conformational shape change and brings the molecule in

Question 16

Define ion channels and their properties

Answer 16

-Also a carrier protein, but it is for ions.
-ions flow down the electrochemical gradient
-it is has a membrane potential (meaning that it is electrically charged)
-cations go into the cell, anions leave the cell

Question 17

Define glycoproteins and their properties

Answer 17

1. Responsible for cell to cell signaling. They receive signals and can cause shape changes to proteins (think of Venus fly trap reacting after something touches one of the sensors)

Question 18

Define sodium potassium pumps and their properties

How is it powered?

Answer 18

1. It is a Transport protein that pumps 3 sodium’s out of the cell and 2 potassium into the cell
2. Doing this creates an electrochemical gradient because they are ions
3. Powered by ATP
4. Undergoes a shape change

Question 19

Define proton pumps and their properties

Answer 19

1. Pumps hydrogen ions out of the cell and forms membrane potential.
2. Stores energy (ATP) and is always running

Question 20

Define Cotransport pump and its properties

Answer 20

1. Think of a key to a lock. Downhill diffusion of one molecule attaches to the protein and is like the “key” for the other molecule to lock on.
2. Once both are locked on, they can pass through

Question 21

What is diffusion? Does it need energy?

Answer 21

-No ATP needed
-is high to low
-certain things can just diffuse across the membrane (ex. Small non polar molecules like O2 and CO2)

Question 22

What molecules can just pass through the plasma membrane?

Answer 22

CO2 and O2

Question 23

What is facilitated diffusion? How is it different from just diffusion? Does it need ATP?

Answer 23

1. It is diffusion that requires a channel or carrier protein
2. Helps polar molecules get across the cell membrane
3. No ATP required

Question 24

What is Osmosis? What are its properties? Does it require ATP?

Answer 24

1. The diffusion of water
2. High to low
3. No ATP
4. Helps even out the concentration of solutes (not the volume)

Question 25

Name the three types of osmosis occurrences or scenarios

Answer 25

1. Hypertonic
2. Hypotonic
3. Isotonic

Question 26

Define hypertonic. Does the cell shrivel up or swell?

Answer 26

1. When the environment outside is more concentrated than inside the cell
2. Water leaves the cell
3. The cell shrivels up (think of pouring salt on a mummy)

Question 27

Define hypotonic. Does the cell shrink or shrivel up?

Answer 27

1. Happens when there is more concentration on the inside of the cell
2. Water flows into the cell
3. The swell swells up, burst or lyse

Question 28

What is Isotonic? Does it cause the cell to swell or shrivel up?

Answer 28

1. Both concentrations are equal
2. No cells dies
3. Water diffuses proportionally in and out of the cell