Chapter 4 - Transport across cell membranes

Question 1

What do phospholipids do?

Answer 1

Form a bilayer

Question 2

What is the structure of phospholipids

Answer 2

Hydrophillic head - Points to outside of cell and attracted to water
Hydrophobic Tail - Facing inside the cell

Question 3

What small non-polar molecules can diffuse through the membrane?

Answer 3

O2 AND CO2 - rapidly diffuse

Question 4

What small polar molecules can diffuse through the membrane?

Answer 4

H2O + Urea

Question 5

What is unlikely to diffuse through the membrane?

Answer 5

charged particles (ions)

Question 6

What is the function of cholesterol?

Answer 6

V.important in controlling membrane fluidity + keeping the membrane in stable normal body temp (without it cells would burst)
More cholesterol = less fluid = less permeable, the membrane

Question 7

What are integral (Intrinsic or Transmembranes) proteins?

Answer 7

Proteins that span the whole wrath of the membrane

Many are carrier or channel proteins

Question 8

What are peripheral (extrinsic) proteins?

Answer 8

Proteins are confined to the inner or outer surface of the membrane
May be free on the membrane surface or bound to integral protein

Question 9

What are glycoproteins?

Answer 9

Proteins with attached carbohydrate chains

Question 10

What are the functions of (Intrinsic or Transmembranes)

Answer 10

Help transport substances such as ions, sugars, amino acids that can’t diffuse through membrane but are still vital to cells functioning

Question 11

What are the functions of (extrinsic) proteins?

Answer 11

Act as receptors for hormones or neurotransmitters or involved with cell recognition

Question 12

Why is the fluid mosaic model described as ‘fluid’?

Answer 12

because individual phospholipid can move relative to each other
Gives a flexible structure

Question 13

Why is the fluid mosaic model described as ‘mosaic’?

Answer 13

Proteins embedded in phospholipid vary in shape size + pattern

Question 14

What is simple diffusion?

Answer 14

passive transport (natural, inbuilt motion of particles)

Question 15

What is the definition of diffusion?

Answer 15

Is the net movement of molecules or ions from a region where they are highly concentrated to one where their conc is lower until evenly distributed down a conc gradient

Question 16

What is facilitated diffusion?

Answer 16

passive process that relies on inbuilt KE of diffusing molecule
Down a conc gradient
differs

Question 17

What two proteins are involved in facilitated diffusion?

Answer 17

Protein channels

Carrier proteins

Question 18

What are protein channels?

Answer 18

Water filled hydrophilic channels across the membrane

Question 19

What is the function of channel protein?

Answer 19

Selectively slow water-soluble ions to pass through
controls entry + exit
opens one side closes one side

Question 20

What are carrier protein?

Answer 20

alternative form of FD

involves carrier proteins that span the plasma membrane

Question 21

What is the function of carrier protein?

Answer 21

molecule specific to protein is present 
binds with protein 
causes to change shape 
molecule released to inside of membrane 
Molecules move from H to L conc

Question 22

What is the definition of osmosis?

Answer 22

the passage of water from a region where it has a H water potential to a region of L water potential through selectively permeable membrane

Question 23

What is water potential?

Answer 23

the pressure created by water molecule under standard temp + pressure

Question 24

Whats hypertonic?

Answer 24

WP outside is L than inside the cell
H2O moves out of cell
Cell is plasmolyzed (cytoplasm pulled from cell wall)

Question 25

Whats isotonic?

Answer 25

f

Question 26

Whats Hypotonic?

Answer 26

WP outside H than inside the cell
H2O enters cell
Cell is Turgid (Cytoplasm pushing against cell wall)

Question 27

What is the definition of active transport?

Answer 27

The movement of molecules or ions out of a cell from a region of lower conc to a region of higher conc using ATP and carrier proteins

Question 28

What is ATP used in AT for?

Answer 28

Directly move molecules

Individually move molecules using conc gradient

Question 29

How does it differs from passive forms of transport?

Answer 29

Uses metabolic energy in form of ATP
substances moved against conc
Carrier proteins acts as pump
Process is selective

Question 30

Describe the process of direct active transport?

Answer 30

1) Carrier proteins span plasma membrane

Question 31

What is cotransport?

Answer 31

Indirect active transport (coupled transport)?

Question 32

What is the role of AT in absorbtion in microvilli?

Answer 32

d