Mr P- bio 6 cell membranes

Question 1

What are the charges on the different groups within a phospholipid?

Answer 1

Phosphate group has a negative charge (polar) and fatty acids don’t have a charge (non-polar)

Question 2

Which part of the phospholipid is hydrophilic and which part is hydrophobic?

Answer 2

Phospho-glycerol head= hydrophilic
Fatty acid tails= hydrophobic

Question 3

What is the structure of the plasma membrane described as?

Answer 3

Fluid mosaic

Question 4

Why is a cell membrane described as a fluid mosaic?

Answer 4

FLUID= the phospholipids are constantly movi mg about giving a fluid structure
MOSAIC= protein molecules are unevenly distributed throughout the membrane, forming a mosaic

Question 5

What try or if substances does a phospholipid bilateral act as a barrier to?

Answer 5

Polar molecules and ions

Question 6

Why is the phospholipid bilayer acting as a barrier to most water soluble substances useful?

Answer 6

Ensures water- soluble molecules such as sugars, amino acids and proteins cannot leak out of cell and unwanted water-soluble molecules cannot get in

Question 7

What does a phospholipid bilayer allow to pass through?

Answer 7

Small non charged (Lipid- soluble molecules)

Question 8

What do ions and polar molecules pass through?

Answer 8

Channel proteins

Question 9

What two processes do carrier proteins carry out?

Answer 9

Facilitated diffusion and active tranpsort

Question 10

What does cholesterol do?

Answer 10

Regulates the fluidity of the membrane

Question 11

Other than carrier and channel proteins, what can other proteins be within the membrane?

Answer 11

Specific receptors for hormones

Question 12

What are the ‘channel proteins’ that allow water in called?

Answer 12

Aquaporins

Question 13

What are the two types of receptors?

Answer 13

Glycolipids and glycoproteins

Question 14

What do glycolipids and glycoproteins contain allowing them to act as receptor molecules?

Answer 14

Carbohydrate chains

Question 15

What are the 3 main receptor types?

Answer 15

Signalling receptors (hormones and neurotransmitters), receptors involves in endocytosis and receptors involved in cell adhesion and stabilisation

Question 16

What are the 4 types of movement of substances ina do out of the cell?

Answer 16

Diffusion, facilitated diffusion, osmosis and active transport

Question 17

What is facilitated diffusion?

Answer 17

A hydrophilic substance can’t pass through hydrophobic phospholipid bilayer so instead move through he membrane via channel or carrier proteins

Question 18

What do channel proteins allow to diffuse through the cell membrane?

Answer 18

Charged substances (e.g. ions)

Question 19

What does the direction of movement of molecules through the carrier proteins depend on?

Answer 19

The relative concentration on each side of the membrane

Question 20

Is facilitated diffusion a passive or active process and how long does it occur for?

Answer 20

Passive and until it reaches equilibrium

Question 21

Is movement using a carrier protein passive or active process?

Answer 21

Active (active transport)

Question 22

Why is movement through a carrier protein active tranpsort?

Answer 22

Moves against the conc gradient

Question 23

What is the water potential?

Answer 23

Pressure of water on the membrane

Question 24

What is the water potential of water?

Answer 24

0

Question 25

More water molecules = ________ water potential

Answer 25

Greater

Question 26

What happens when a substance binds to a carrier protein?

Answer 26

The tertiary structure changes

Question 27

Give 2 examples of large molecules transported by a carrier protein?

Answer 27

Glucose and amino acids

Question 28

Where are enzymes that digest disaccharides found?

Answer 28

Cell surface membrane of epithelial cells that line the small intestine

Question 29

What do glycoproteins aid with?

Answer 29

Cell recognition and or as antigens

Question 30

What is passive diffusion?

Answer 30

From high to low conc, through phospholipid bilayer, passive