Cellular Physiology 1 - Organisation & Transport

Question 1

What is the basic unit structure of the body?

Answer 1

Cells

Question 2

What are the 3 main parts of a cell?

Answer 2

Nucleus
Cytoplasm
Plasma Membrane

Question 3

What does the cell membrane separate?

Answer 3

The intracellular fluid (ICF) from the extracellular fluid (ECF)

Question 4

What is cell membrane made from?

Answer 4

Phospholipids

Question 5

What do phospholipids consist of?

Answer 5

Polar phosphate head
2 non-polar fatty acid tails

Question 6

Phosphate heads are…

Answer 6

Hydrophilic

Question 7

Non-polar fatty acid tails are…

Answer 7

Hydrophobic

Question 8

How do 2 phospholipid molecules align themselves?

Answer 8

With their tails facing each other, which then forms the phospholipid bilayer of the cell membrane

Question 9

What may be inserted within or attached to the bilayer?

Answer 9

Protein Molecules

Question 10

Are Some proteins able to move within membrane?

Answer 10

Yes, Protein icebergs floating in a sea of lipid

Question 11

What can be found on the outer surface of a membrane?

Answer 11

Carbohydrates

Question 12

What to glycolipids bind to?

Answer 12

Bound to lipids

Question 13

What do glycoproteins bind to?

Answer 13

Bound to proteins

Question 14

What is the fluid mosaic model?

Answer 14

The structure of the cell membrane & all components found within or on it

Question 15

What are the major components of the fluid mosaic model?

Answer 15

Phospholipid bilayer
Proteins
Lipids
Carbohydrates

Question 16

What forms the basic structure of a cell membrane?

Answer 16

phospholipid bilayer

Question 17

What prevents large hydrophilic
solutes crossing
membrane unaided?

Answer 17

phospholipid bilayer

Question 18

What do membrane protein act as?

Answer 18

Channels
Carrier molecules
Receptors
Membrane-bound enzymes
Cell adhesion molecules (CAM’s)

Question 19

What is passive (simple) diffusion?

Answer 19

Movement of solute from a region of high concentration to region of low concentration
across selectively permeable membrane

Question 20

Give examples of passive diffusion.

Answer 20

Responsible for transport of H2O across membranes
Important for ions, small non-polar molecules & gases (O2& CO2)
Pass directly through the lipid matrix of membrane

Question 21

Does passive diffusion require energy expenditure?

Answer 21

No, Underpinned by chemical driving force & concentration gradient. Materials move down a concentration gradient

Question 22

Tell me about Flux.

Answer 22

Magnitude of chemical driving force is proportional to concentration gradient
Net flux is directly proportional to the size
of the concentration gradient
The more permeable the membrane, the
higher the rate of transport

Question 23

Rate of diffusion can be predicted using who’s law of diffusion?

Answer 23

Fick’s Law of Diffusion

Question 24

What is facilitated transport?

Answer 24

Transport mechanism for large / polar molecules that cannot cross cell membrane by passive
diffusion (e.g. glucose & amino acids)

Question 25

Facilitated transport obeys Fick's law? True or False

Answer 25

False, Does not obey Fick’s Law - Rate of transport exceeds that predicted by Fick’s Law

Question 26

Tell me more about facilitated diffusion.

Answer 26

Involves solute molecules binding to protein carriers embedded in membrane Diffusion brings solute to binding site of carrier and moves it away from carrier on other side of membrane

Question 27

What 3 factors is facilitated diffusion determined by?

Answer 27

Type of individual carriers The number of carriers in a membrane Magnitude of concentration gradient

Question 28

In facilitates transport, Diffusion plateau as a result of what?

Answer 28

concentration gradient & number of carriers

Question 29

What is active transport?

Answer 29

Movement of solute from a region of low concentration to a region of high concentration across a selectively permeable membrane

Question 30

In active transport, which direction do solutes travel?

Answer 30

against a concentration gradient

Question 31

What energy does active transport require?

Answer 31

ATP

Question 32

What are the two forms of active transport?

Answer 32

Primary and Secondary active transport

Question 33

What is the Electrochemical gradient?

Answer 33

Difference in solute concentration across a membrane & the electrical gradient across a membrane

Question 34

In what direction do Ions move in active transport?

Answer 34

Ions moving up the electrochemical gradient harnesses energy

Question 35

In what direction do Ions move in passive transport?

Answer 35

Ions move down the electrochemical gradient - Releases energy to drive the flow of the other

Question 36

What proteins harness energy to drive transport in a specified direction?

Answer 36

Transport proteins

Question 37

What affinity do carrier proteins have?

Answer 37

Equal affinity - Equal on both sides of membrane

Question 38

What affinity do transport proteins have?

Answer 38

Unequal affinity - Greater on one side of membrane

Question 39

What outweighs the effect of affinity?

Answer 39

Effects of concentration gradient

Question 40

What is the difference between Affinity and Concentration?

Answer 40

Affinity - Ions want to be on this side Concentration - Ions don’t want to be on this side

Question 41

True or False? Active transporters are specific for certain molecules

Answer 41

True

Question 42

Do active transporters have a fixed number of binding sites

Answer 42

Yes

Question 43

What is primary active transport?

Answer 43

Solute transported via proteins that serve as pumps

Question 44

What is secondary active transport?

Answer 44

Transport that is powered by an electrochemical gradient previously created by primary active transport

Question 45

What is ATPases?

Answer 45

Responsible for harnessing ATP

Question 46

Secondary active transport can be divided into what?

Answer 46

Symport (Co-Transport) Antiport (Counter Transport)

Question 47

What is a symport?

Answer 47

2 solutes move in same direction across membrane Couples inward flow/outward of 2 (or more) different solutes Solute 1 moves against the concentration gradient Movement of solute 1 increases affinity of solute 2 receptors Solute 2 flows against gradient with solute 1

Question 48

What is an antiport?

Answer 48

Solutes move in opposite directions across membrane Inward flow of solute 1 & outward flow of solute 2 Solute 1 requires energy to move across membrane Protein receptor has high affinity for solute 1 on one side & a high affinity for solute 2 on the other side Solute 2 moves across the membrane in opposite direction to solute 1

Question 49

What is the Na+/K+ pump?

Answer 49

3 sodium (Na+) binding sites 2 potassium (K+) binding sites ATP transports Na+ out of cell K+ into cell (via electrochemical gradient)

Question 50

How does the Na+/K+ pump work?

Answer 50

Intracellular Na+ binds to the pump Binding of 3 X Na+ causes phosphorylation (via ATP) Binding of 3 X Na+ & phosphorylation cause conformational change in protein (shape) Extracellular K+ bind to pump & triggers release of phosphate group Release of phosphate group allow protein to return to original conformation K+ ions are released into intracellular space

Question 51

What is osmosis?

Answer 51

Transport of water across cell membranes / capillary walls Movement of water from region of low solute concentration to region of high solute concentration High solute = low water | Low solute = high water

Question 52

Is osmosis active or passive?

Answer 52

Always passive - Unaffected by membrane potentials

Question 53

What is osmotic pressure?

Answer 53

Osmotic pressure - Ability to ‘pull’ water Water moves from a region of low osmotic pressure to a region of high osmotic pressure Controlled by amount of osmotically active particles it contains Indirect measure of solute concentration Osmotic pressure of solution controlled by amount of osmotically active particles it contains