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The Cell > Cellular Membranes > Flashcards

Cellular Membranes Flashcards

1
Q

Function of the Fluid Mosaic Model

A

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

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2
Q

What do lipids do in the FMM

A

barrier for water soluble molecules

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3
Q

What separates two aqueous regions

A

Phospholipid bilayer

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4
Q

Integral membrane proteins

A

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

(Embedded)

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5
Q

Transmembrane proteins

A

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

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6
Q

Peripheral membrane proteins

A

Lack hydrophobic regions and are not embedded in the bilayer

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7
Q

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

A

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

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8
Q

What is a glycoprotein

A

carbohydrate in the membrane is covalently bonded to proteins

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9
Q

What are plasma membrane glycoproteins responsible for

A

enables cells to be recognised by other cells and proteins

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10
Q

What are glycoproteins in the lipid membrane involved in

A

cell- cell interactions

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11
Q

What are the two cell adhesion molecules

A

Homotypic
Heterotypic

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12
Q

What is homotypic binding

A

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

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13
Q

What is heterotypic binding

A

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

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14
Q

3 types of animal cell junctions

A

tight junctions
desmosomes
gap junctions

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15
Q

What are tight junctions in animal cells

A

specialised structures at the plasma membrane that link adjacent epithelial cells

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16
Q

function of tight junctions in animal cells

A
  1. restrict migration of membrane proteins and phospholipids
  2. prevent substances from moving through intracellular space
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17
Q

What are desmosomes in animal cells

A

act like spot welds on adjacent cells, holding them together

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18
Q

What are gap junctions in animal cells

A

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

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19
Q

What is facilitated diffusion

A

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

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20
Q

diffusion

A

the passive movement towards the state of equilibrium

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21
Q

Effects of diffusion rates

A

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

22
Q

Osmosis

A

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

23
Q

What ae=re isotonic solutions

A

equal solute concentrations

24
Q

What is a hypertonic solution

A

It has a greater total solute concentration than the solution

25
Q

What is a hypotonic solution

A

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

26
Q

What two types of membrane proteins does Facilitated diffusion rely on

A

channel and carrier proteins

27
Q

What are channel proteins

A

integral membrane proteins that form channels linked with polar amino acids

28
Q

What type of amino acid faces the outside of the channel

A

nonpolar (hydrophobic)

29
Q

how is the potassium ion channel activated

A

a change in voltage across the membrane

30
Q

Carrier proteins

A

allow diffusion in both directions

31
Q

Facilitated diffusion using carrier proteins

A

involves opening a channel and binding the transported substance

32
Q

How can the concentration gradient be kept during facilitates diffusion

A

by metabolising the transported substance once it enters the cell

33
Q

What is needed for active transport

A

ATP

34
Q

Three different protein driven systems that are involved in active transport

A

Uniport, Symport, Antiport

35
Q

Uniport transporters

A

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

36
Q

Symport transporters

A

move two solutes in the same direction

37
Q

Antiport transporters

A

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

38
Q

Primary active transport

A

The sodium potassium pump

39
Q

What cations use primary active transport

A

Sodium, potassium and calcium

40
Q

Secondary active transport

A

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

41
Q

example of symport system

A

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

42
Q

How does the secondary active transport system work

A

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

43
Q

What is the process endocytosis

A

brings macromolecules, particles and other cells into the eukaryotic cell

44
Q

Three types of endocytosis

A

Phagocytosis, Pinocytosis and receptor mediated endocytosis

45
Q

Phagocytosis

A

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

46
Q

Pinocytosis

A

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

47
Q

Pinocytotic in humans

A

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

48
Q

Receptor mediated endocytosis

A

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

49
Q

What is Exocytosis

A

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

50
Q

Functions of membrane

A
  • organising chemical reactions
  • information processing
  • energy transformation
51
Q

Functions of membrane

A
  • organising chemical reactions
  • information processing
  • energy transformation

The Cell (18 decks)

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