Membranes and membrane transport

Question 1

what are the four types of membranes?

Answer 1

nuclear, plasma, mitochondrial and endoplasmic reticulum

Question 2

What is the basic structure of the phospholipid bilayer

Answer 2

Hydrophilic head, hydrophobic fatty acid chains with intergral and perhipheral proteins and carbohydrates

Question 3

describe carbohydrates in phospholid membrane.

Answer 3

associated with membrane, attached to lipid and proteins and recognises specific molecules

Question 4

what effects the fluidity of the phospholipid membrane?

Answer 4

temperature, fatty acid chain length, bonding and presence of cholestrol

Question 5

what varies in membrane composition?

Answer 5

amount of proteins, cholestrol, carbohydrates and lipids.

Question 6

If the membrane gets more heat….

Answer 6

it becomes more fluid as lipids move around

Question 7

if the membrane gets more cold….

Answer 7

less fluid as the chains pack tightly together and are laterally organised.

Question 8

What is the effect of fatty acids on phospholipid protein?

Answer 8

Long chain = more stiff, shorter chain = less stiff

Question 9

What is the impact of double bonds in the phospholipid membrane?

Answer 9

makes the fatty acids un-saturated which makes the membrane more stiff.

Question 10

What is the effect of cholestrol in a low temperature?

Answer 10

increases fluidity of the membrane

Question 11

what is the impact of cholestrol in a high temperature?

Answer 11

decreases fluidity.

Question 12

Where are proteins in the phospholipid membrane?

Answer 12

freely migrating or anchored to a specific region.

Question 13

what is an example of a protein that is bound to cell wall?

Answer 13

Neuronal transmitter protein in plasma membrane of muscle cell. it recognises a chemical signal from a neuron.

Question 14

what is the ECM made up of?

Answer 14

collagen, fibronectin and heparin

Question 15

what do membrane proteins bind to?

Answer 15

the ECM

Question 16

What is the role of integrins ?

Answer 16

maintains structure as it binds to ECM and filaments

Question 17

what is the importance of cholesterol in membrane proteins?

Answer 17

membrane integrity, source of production for hormones, vitmian D and bile and regulate s fluidity

Question 18

Is the outside of the cell more postive or negative when compared to the inside? Why

Answer 18

Positive. More posotive ions (Ca, K and Na)

Question 19

What is hypertonic (on the outside)?

Answer 19

solutes concentrated on the outside of the cell

Question 20

What is isotonic?

Answer 20

solute concentration is equal on each side of the cell

Question 21

what is hypotonic (on the outside)?

Answer 21

Less solute on the outside of the cell.

Question 22

what is a clinical example of osmosis?

Answer 22

Red blood cells.

Question 23

What happnes when red blood cells are hypotonic on the outside

Answer 23

not enough solute on the outside, cell takes in water and bursts = poor kidney function

Question 24

What are three types of passive transport?

Answer 24

Simple diffusion, facilitated diffusion and osmosis.

Question 25

What can move through simple diffusion?

Answer 25

CO2, O2 and lipid soluble subtnaces (steroids)

Question 26

How does simple diffussion occur?

Answer 26

The molecules engage in random collisions with like molecules.

Question 27

What is an example of faciliated channel?

Answer 27

Aquaporin (in red blood cells and kidney) where water goes through hydrophilic channel

Question 28

How does facilated diffusion with a carrier protein work?

Answer 28

molecule binds to specfic carrier --> it chnages shape --> allows to come in

Question 29

what are the two classes of carrier proteins?

Answer 29

Symporters and antiporters

Question 30

what are symporters?

Answer 30

Simultaneously transports sugar and ion

Question 31

what is an example of symporter carrier protein?

Answer 31

Na and Glucose.

Question 32

What are antiporters?

Answer 32

Where one solute moves in ONE direction whilst the second moves in ANOTHER.

Question 33

What is an example of a antiporter carrier protein?

Answer 33

Na and Ca in cardiac muscles

Question 34

What is primary active transport?

Answer 34

When molecules move against the concentration gradient using energy from ATP.

Question 35

How does the Na/K ATPase (primary active) function?

Answer 35

3 Na+ bind to protein pump INSIDE cell --> ATP breaks into ADP --> protein pump changes shape --> Na is expelled from the cell --> K binds to protein pump (now open to outside) --> K enters the cell.

Question 36

What is secondary active transport?

Answer 36

The energy from the primary transport creates a ion gradient which is used to transport another compound.

Question 37

What is an example of secondary active transport?

Answer 37

Na+ gradient using Na symporter

Question 38

How does the Na symporter work?

Answer 38

Na moves down concetration gradient --> allows for uphill transport of glucose (cotransportred substate)

Question 39

What is a clinical example of Primary Active transport?

Answer 39

Heart disease- Digoxin is a treatment for heart disease as it increases foce of hear contraction. It inhibits Na/K ATPase. This lowers Na gradient = less Ca exported = stronger muscle contractions

Question 40

What are the three processes in which macromolecules move?

Answer 40

Phagocytosis, pinocytosis and receptor-mediated endocytosis.

Question 41

How does phagocytosis occur?

Answer 41

partcile binds to cell surface --> polymerisation and depolumerisation of actin microfilaments --> vacuole forms --> fuses with lyosomes --> digested by enzymes

Question 42

What are the two roles of receptor- mediated endocytosis?

Answer 42

1- uptake of nutrition 2. Waste disposal

Question 43

Describe the mechanism of action for receptor-mediated endocytosis.

Answer 43

Plasma membrane folds inwards --> folds into a small pocket around materials --> pocket deepens forming a vesicle --> vesicle separates from plasma and migrates contents to centre

Question 44

What are the main differences between carrier and channel?

Answer 44

Binding (carrier binds), speed (channel is faster) and make up (channel= tunnel/pore, Carrier= conformational change)

Question 45

What is the difference between peripheral and integral proteins?

Answer 45

Peripheral = surface whilst intergal is all the way through.

Question 46

What is the role of intergrin and how?

Answer 46

ntegrins: bind ECM and to actin filaments (part of cytoskeleton) on inside