0.6 The Plasma Membrane

Question 1

Where are plasma membranes found?

Answer 1

Found around the cell itself and around each organelle

Question 2

List functions of the cell membrane

Answer 2

-Regulate which materials can enter and exit the cell
-Maintains homeostasis
-Separates cellular materials from external environment

Question 3

What are semipermeable membranes?

Answer 3

Membranes that allow certain materials to pass through based on certain properties such as:
- Size
- Charge

Question 4

What are the functions of phospholipids and proteins in the plasma membrane?

Answer 4

While phospholipids provide the basic structural organization of membranes, membrane proteins carry out the specific functions of the different membranes of the cell.

Question 5

What is passive transport?

Answer 5

Materials move DOWN the concentration gradient
Equilibrium is reached
No energy in needed

Question 6

What is active transport?

Answer 6

Materials move UP the concentration gradient
Concentrations become unbalanced
Energy is required to move

Question 7

In active transport, what form of energy is required?

Answer 7

ATP

Question 8

What is a phospholipid?

Answer 8

A type of lipid that ahs 2 fatty acid tails (tails repel water) and a phosphate head (head is attracted to water). They form a layer called the phospholipid layer.

Question 9

Why does the phospholipid layer form?

Answer 9

Because the heads attract water and the tails repel it, they are arranged in a way that only allows the heads to touch the water outside and inside the cell, keeping the tails on the inside.

Question 10

What type of membrane is the phospholipid layer?

Answer 10

It is a semipermeable layer because it only allows certain molecules to pass through.

Question 11

How do hydrophilic, polar, large and charged molecules pass into the cell?

Answer 11

They use a carrier protein.

Question 12

List the 2 types of carrier proteins

Answer 12

Protein channels and protein pumps.

Question 13

Explain a protein pump

Answer 13

These carrier proteins use ATP energy to increase the concentration on one side of the membrane.

Question 14

Explain endocytosis

Answer 14

A way in which materials enter the cell without crossing the membrane.
The membrane folds around the particle and forms a new vacuole inside the cell.

Question 15

Explain exocytosis

Answer 15

Vesicles fuse/connect themselves to the cell membrane to release (secrete) their contents into the cell.

Question 16

What is the difference between diffusion and the use of a protein pump?

Answer 16

Diffusion does NOT require any ATP energy, it also takes place DOWN the gradient of concentration to create equilibrium. Protein pumps DO require energy, and takes place UP the gradient of concentration to unbalance the concentration.

Question 17

What is the role of integral proteins?

Answer 17

The aid in the movement of molecules across the cell

Question 18

What is the role of peripheral proteins?

Answer 18

They aid with molecule transfer into and out of cell (carrier proteins)

Question 19

What is the role of cholesterol in the plasma membrane?

Answer 19

Help with flexibility, and help communicate with other cells when connected to carbohydrates.