Cell Membranes

Question 0

What is the main part of the membrane?

Answer 0

Phospholipid bilayer

Question 1

Approximately how thick is the membrane?

Answer 1

7nm

Question 2

Which end of the phospholipid do glycoproteins/lipids attach to?

Answer 2

Hydrophilic

Question 3

What do antigens do?

Answer 3

Cause antibody reaction

Question 4

What does cholesterol do?

Answer 4

Controls fluidity
Steroid- lipid
Makes membrane less permeable to charged/polar particles

Question 5

Define transmembranous protein

Answer 5

Carrier protein with channel to allow transport in and out of cell

Question 6

Define intrinsic protein

Answer 6

Protein on surface that doesn’t permeate membrane

Question 7

What can proteins act as in the membrane?

Answer 7

Enzymes

Question 8

What do glycoproteins do?

Answer 8

Binding site (for neurotransmitters, hormones etc)
Antigens
Stabilisation
Receptors for cell signalling

Question 9

How can foreign microbes make detection more difficult?

Answer 9

Change the structure of their surface cell proteins

Question 10

FLUID MOSAIC MODEL

Explain pls.

Answer 10

Fluid- molecules free to move in/out

Mosaic- made up of different proteins embedded in a phospholipid bilayer

Question 11

Name for burst animal cell (in hypotonic solution)

Answer 11

Lysed (lysis)

Question 12

Define tonicity

Answer 12

Difference in water concentration of two solutions separated by a semipermeable membrane

Question 13

Define hypotonic

Answer 13

Lower concentration outside cell

Water enters

Question 14

Define hypertonic

Answer 14

Higher concentration outside cell

Water leaves

Question 15

Name for when cell shrinks due to water loss

Answer 15

Crenated

Question 16

What is ATP broken down into after active processes?

Answer 16

ADP
and
Inorganic phosphate

Question 17

Rate of diffusion depends upon what?

Answer 17

Concentration gradient
Temperature
SiZe oF PaRtiCLeS
Surface area

Question 18

What kind of particles need special pathways to cross the plasma membrane?

Answer 18

Charged/polar molecules

Question 19

What does the sodium-potassium pump do?

Answer 19

Aids the active transport of sodium and potassium in/out of cells against the concentration gradient. Uses ATP

Question 20

When one ATP is broken down in the sodium-potassium pump, what happens?

Answer 20

Two potassium atoms are taken in

Question 21

When is facilitated diffusion used?

Answer 21

To transport LARGE and/or highly charged ⚡ particles

Question 22

Facilitated diffusion moves substances _____ the concentration gradient

Answer 22

Down

Question 23

Two types of facilitated diffusion

Answer 23

Channel proteins change shape

Ion specific channels

Question 24

Conditions for high water potential?

Answer 24

Solution with: A lot of water ☔ Under a lot of pressure

Question 25

Three mechanisms of cell signalling?

Answer 25

1⃣Receptor acts as ION CHANNEL 2⃣Receptor activates G-PROTEIN 3⃣Receptor acts as ENZYME

Question 26

How do ion channels work?

Answer 26

Chemical signal activates proteins, which open to form channel

Question 27

How does g-protein activation work?

Answer 27

Signal molecule➡ receptor➡ g-protein

Question 28

How do receptor-enzyme hybrids work?

Answer 28

Signal molecule brings two parts together, activates cytoplasm-side enzymes, causes response.

Question 29

Mechanism of endocytosis?

Answer 29

Plasma membrane surrounds particle by folding. Makes vesicle inside.

Question 30

Mechanism of exocytosis

Answer 30

Vesicles pinch off from the Golgi, travel through plasma membrane, fuse with membrane and release contents.

Question 31

Why doesn't H2O need facilitated diffusion?

Answer 31

Although it's polar, it's small enough to pass through transmembranous proteins.

Question 32

True or false | Plasma membranes can allow an electrical current to pass along them

Answer 32

True

Question 33

Why are the heads of phospholipids hydrophilic?

Answer 33

They have a tiny charge which attracts the water

Question 34

How does cholesterol regulate fluidity?

Answer 34

Ensures plasma membrane doesn't become too stiff when cold or too fluid when hot

Question 35

How do small, non-polar substances enter cell?

Answer 35

Passive diffusion

Question 36

How do large substances enter?

Answer 36

Endocytosis using ATP

Question 37

How do polar substances enter?

Answer 37

Facilitated diffusion

Question 38

Differences between active transport and facilitated diffusion

Answer 38

FD not against conc grad | AT uses ATP

Question 40

Function of plasma membrane

Answer 40

Control in/out Cell signalling Receptor

Question 41

Role of membranes inside cells

Answer 41

Compartmentalisation Inc surface area Vesicles Partially permeable- control in/out of organelle

Question 42

Outline mechanism of exocytosis

Answer 42

Vesicle forms at Golgi | Transported along microtubules

Question 43

How do phospholipids control fluidity of plasma membrane?

Answer 43

When unsaturated, membrane is more fluid Because The kink in the tail of the unsaturated lipid means the molecules can't sit closely together