Membranes

Question 1

What is the structure of a phospholipid?

Answer 1

Glycerol, two fatty acids and a phosphate group

Question 2

What’s the difference between intrinsic and extrinsic proteins?

Answer 2

Intrinsic proteins pass right through the membrane such as carrier and channel proteins, extrinsic do not pass the entire way through, or are only on the outside

Question 3

What does the fluid mosaic model mean?

Answer 3

The model is called fluid because the phospholipid and protein molecules move around each other. The model is called a mosaic because proteins embedded between the phospholipids vary in shape, size and patter

Question 4

What is the function of glycoproteins and glycolipids in the cell membrane?

Answer 4

Cell to cell communication and recognition

Question 5

What is the function of cholesterol in the cell membrane?

Answer 5

To regulate fluidity

Question 6

How do lipid soluble substances pass through the cell membrane?

Answer 6

They can dissolve in the fatty acid tails and move through the membrane by simple diffusion

Question 7

How do ions pass throught the cell membrane?

Answer 7

They must pass through a channel protein by facilitated diffusion

Question 8

What is active transport?

Answer 8

Movement from an area of low to high concentration, against a concentration gradient. This is done through a carrier protein and requires ATP

Question 9

Which transport protein is used for active transport?

Answer 9

A carrier protein

Question 10

What is the specific term for bulk transport of a solid into a cell?

Answer 10

Phagocytosis (A type of endocytosis)

Question 11

What is the term for bulk transport out of a cell?

Answer 11

Exocytosis

Question 12

Why do endocytosis and exocytosis require ATP?

Answer 12

ATP is required to provide energy to move the cell membrane

Question 13

What is osmosis?

Answer 13

Water molecules move from a high water potential to a low water potential through a selectively permeable membrane.

Question 14

Hypotonic means

Answer 14

A solution with a higher water potential than a cell

Question 15

Hypertonic means

Answer 15

A solution with a lower water potential than a cell

Question 16

Isotonic means

Answer 16

A solution with the same water potential as a cell

Question 17

What does increasing temperature do to the cell membrane?

Answer 17

As temperature increases the membrane becomes more fluid, and slightly more permeable. When the temperature increases too much proteins will denature and lost their shape, creating pores that make the membrane even more permeable.

Question 18

Why do phospholipids form a bilayer?

Answer 18

The hydrophobic fatty acid tails point towards the middle of the membrane, away from water. The hydrophilic phosphate heads point outwards, as they are attracted to water.