Cellular Membranes

Question 1

Function of the Fluid Mosaic Model

Answer 1

Bilayered structure that;
- perform vital physiological roles
- form boundaries
- regulate molecules that enter and exit the cell
= lipids, carbohydrates and proteins make these possible

Question 2

What do lipids do in the FMM

Answer 2

barrier for water soluble molecules

Question 3

What separates two aqueous regions

Answer 3

Phospholipid bilayer

Question 4

Integral membrane proteins

Answer 4

hydrophobic regions of amino acids that penetrate or cross the phospholipid bilayer

(Embedded)

Question 5

Transmembrane proteins

Answer 5

Specific orientation - two faces on both sides of the phospholipid bilayer

Question 6

Peripheral membrane proteins

Answer 6

Lack hydrophobic regions and are not embedded in the bilayer

Question 7

Why are some proteins restricted in movement across the membrane and cause

Answer 7

They are anchored to components of the cytoskeleton or trapped within regions of the lipid rafts
= this causes unequal distribution of proteins = allowing specialisation of certain regions of the cell membrane

Question 8

What is a glycoprotein

Answer 8

carbohydrate in the membrane is covalently bonded to proteins

Question 9

What are plasma membrane glycoproteins responsible for

Answer 9

enables cells to be recognised by other cells and proteins

Question 10

What are glycoproteins in the lipid membrane involved in

Answer 10

cell- cell interactions

Question 11

What are the two cell adhesion molecules

Answer 11

Homotypic
Heterotypic

Question 12

What is homotypic binding

Answer 12

occurs when both cell posses the same type of cell surface receptor and their interaction causes them to stick together

Question 13

What is heterotypic binding

Answer 13

occurs between two different but complimentary proteins and resembles a plug socket

Question 14

3 types of animal cell junctions

Answer 14

tight junctions
desmosomes
gap junctions

Question 15

What are tight junctions in animal cells

Answer 15

specialised structures at the plasma membrane that link adjacent epithelial cells

Question 16

function of tight junctions in animal cells

Answer 16

1. restrict migration of membrane proteins and phospholipids
2. prevent substances from moving through intracellular space

Question 17

What are desmosomes in animal cells

Answer 17

act like spot welds on adjacent cells, holding them together

Question 18

What are gap junctions in animal cells

Answer 18

connections that facilitate communication between cells
They are made up of protein channels called connexions, these span the plasma membranes of two adjacent cells and protrude them slightly

Question 19

What is facilitated diffusion

Answer 19

molecules must travel through proteins to get into the cell - still diffusion

Question 20

diffusion

Answer 20

the passive movement towards the state of equilibrium

Question 21

Effects of diffusion rates

Answer 21

Effected by
Temp, size of molecule, electrical charge of molecule and concentration gradient

Question 22

Osmosis

Answer 22

Diffusion of water across membranes
high (low solutes) —— low (high solutes)

Question 23

What ae=re isotonic solutions

Answer 23

equal solute concentrations

Question 24

What is a hypertonic solution

Answer 24

It has a greater total solute concentration than the solution

Question 25

What is a hypotonic solution

Answer 25

It has a lower total solute concentration that the solution to which its being compared to

Question 26

What two types of membrane proteins does Facilitated diffusion rely on

Answer 26

channel and carrier proteins

Question 27

What are channel proteins

Answer 27

integral membrane proteins that form channels linked with polar amino acids

Question 28

What type of amino acid faces the outside of the channel

Answer 28

nonpolar (hydrophobic)

Question 29

how is the potassium ion channel activated

Answer 29

a change in voltage across the membrane

Question 30

Carrier proteins

Answer 30

allow diffusion in both directions

Question 31

Facilitated diffusion using carrier proteins

Answer 31

involves opening a channel and binding the transported substance

Question 32

How can the concentration gradient be kept during facilitates diffusion

Answer 32

by metabolising the transported substance once it enters the cell

Question 33

What is needed for active transport

Answer 33

ATP

Question 34

Three different protein driven systems that are involved in active transport

Answer 34

Uniport, Symport, Antiport

Question 35

Uniport transporters

Answer 35

move a single solute such as calcium ions, in one direction

Question 36

Symport transporters

Answer 36

move two solutes in the same direction

Question 37

Antiport transporters

Answer 37

move two solutes in different directions, one into the cell the other out

Question 38

Primary active transport

Answer 38

The sodium potassium pump

Question 39

What cations use primary active transport

Answer 39

Sodium, potassium and calcium

Question 40

Secondary active transport

Answer 40

these systems use established gradients to move substances it uses ATP indirectly

Question 41

example of symport system

Answer 41

intestinal cells, which move glucose up its concentration gradient whilst moving sodium ions down their ion concentration gradient

Question 42

How does the secondary active transport system work

Answer 42

ATP molecules are consumed to establish the ion gradient The gradient is then used to move the substances either Symport or Antiport

Question 43

What is the process endocytosis

Answer 43

brings macromolecules, particles and other cells into the eukaryotic cell

Question 44

Three types of endocytosis

Answer 44

Phagocytosis, Pinocytosis and receptor mediated endocytosis

Question 45

Phagocytosis

Answer 45

common amongst unicellular protists White blood cells use this to defend the body against invading foreign cells

Question 46

Pinocytosis

Answer 46

vesicle formation where the vesicles are far smaller it dissolves substances and fluids brought into the cell

Question 47

Pinocytotic in humans

Answer 47

single layer of cells separating blood capillaries from surrounding tissue uses this to acquire fluid from the blood

Question 48

Receptor mediated endocytosis

Answer 48

is specific Receptor proteins are exposed on the outside of the cell in regions called coated pits. Clathrin form the coats of the pits

Question 49

What is Exocytosis

Answer 49

process by which materials packages in the vesicle are secreted from the cell

Question 50

Functions of membrane

Answer 50

- organising chemical reactions - information processing - energy transformation

Question 51

Functions of membrane

Answer 51

- organising chemical reactions - information processing - energy transformation