Topic 1.3 and 1.4 Membrane structure and transport

Question 1

What was the davson-danielli model?

Answer 1

Phospholipids were in the centre with a layer of protein on either side.

Question 2

Reasons for the D-D model?

Answer 2

It composed of phospholipids and protein
enough red blood cells for there to be twice as many phospholipids
layer of protein acted like a barrier
Electron microscopes showed that there were two dark bands separated by a lighter one and proteins came up darker.

Question 3

What was the evidence that did not fit the D-D model?

Answer 3

Freeze fracture showed globular proteins inside bilayer.
proteins showed parts of their surfaces were hydrophobic
fission of cells with membrane proteins showed proteins could not move

Question 4

What was the new model called?

Answer 4

Singer-Nicolson model or fluid mosaic model

Question 5

What did the fluid mosaic model look like

Answer 5

Had a phospholipid bilayer with different proteins in-between

Question 6

What are characteristics of phospholipid

Answer 6

They are amaphitic - hydrophobic and hydrophilic
when mixed in water form a bilayer
very stable due to bilayer
it is the basic component of all biological membranes

Question 7

Characteristics and function of cholesterol?

Answer 7

it is to stabilise the membrane 
component of animal cell membrane 
have hydrophilic and hydrophobic parts 
restricts movement of phospholipids 
reduces fluidity of membrane 
reduces permeability of membrane

Question 8

What are integral proteins?

Answer 8

intrinsic - Ones that are embedded in phospholipid bilayer they go all the way through or are inside the membrane.

Question 9

What are peripheral proteins?

Answer 9

extrinsic - ones that are attached on an outer surface of membrane outside the membrane or go part way through.

Question 10

What are glycoproteins?

Answer 10

Sugar proteins attached on the outer surface

Question 11

Different membrane proteins?

Answer 11

Insulin receptor
Cytochrome c 
calcium pump
Cadherin
Cytochrome oxidase 
Nicotinic acetylcholine receptor

Question 12

What is the insulin receptor?

Answer 12

Integral protein, hormone receptor

Question 13

What is the Cytochrome c?

Answer 13

peripheral, electron transportation

Question 14

What is the calcium pump?

Answer 14

Integral, active transport of calcium ions

Question 15

What is the Cadherin?

Answer 15

integral, cell to cell adhesion

Question 16

What is the cytochrome oxidase?

Answer 16

integral, immobilised enzyme

Question 17

What is Nicotinic acetylcholine receptor?

Answer 17

Integral, receptor for neuro transmitter, channel for facilitated diffusion of Na+ ions.

Question 18

What is diffusion?

Answer 18

It is passive movement of particles from a region of higher concentration to a region of lower concentration as a result of the random motion of particles, until equilibrium is established.

Question 19

What does it mean to be partially permeable?

Answer 19

That the membrane allows some substances through but not others.

Question 20

What is simple diffusion?

Answer 20

Process where a substance passes through the membrane without aid from a protein within the membrane.

Question 21

What is facilitated diffusion?

Answer 21

Process where substances pass through the membrane but with help from integral proteins. Channel proteins.

Question 22

What is passive transport?

Answer 22

movement of biochemicals and other molecular substances across cell membranes without ATP.

Question 23

What is osmosis?

Answer 23

The passive movement of water molecules from a region of lower solute concentration to a region of higher solute concentration across a partially permeable membrane.

Question 24

Why is the plasma membrane usually permeable to water?

Answer 24

Water is a solvent (liquid in which particles dissolve).

Question 25

What do channel proteins allow through?

Answer 25

Anything with charge

Question 26

What are receptor proteins for?

Answer 26

Electron transport to produce ATP

Question 27

What is ATP?

Answer 27

energy used for a chemical reaction

Question 28

What go directly through the membrane?

Answer 28

alcohol and fats.

Question 29

What is the sugar side chain for?

Answer 29

Cell recognition (glycoprotein)

Question 30

What is cell adhesion?

Answer 30

neighbouring cells stick together

Question 31

What does hypertonic mean?

Answer 31

It is a solution that the cells are in which has a higher concentration than the cell.

Question 32

What dies hypotonic mean?

Answer 32

A solution that the cells are in which has a lower concentration than the cells.

Question 33

What is turgor pressure?

Answer 33

Pressure inside the cell.

Question 34

When is there a risk of Plasmolysis and what is it?

Answer 34

When in a hypertonic solution. It is the shrinking of a cell.

Question 35

When is there a risk of cytolysis and what is it?

Answer 35

In a hypotonic solution is the breaking of a cell when turgor pressure increases.

Question 36

What is active transport?

Answer 36

Movement of molecules across the membrane with the cells providing ATP.

Question 37

What does the protein pump do?

Answer 37

Pumps molecules in and out of a cell.
each pump only pumps certain substances
particles are released on the high concentration side.

Question 38

What proteins are found in the membranes of neurones?

Answer 38

Na+ and K+ channel proteins. they open and close depending on voltage across membrane.

Question 39

What is endocytosis?

Answer 39

The taking in of matter by a living cell to create a vacuole.

Question 40

What is exocytosis?

Answer 40

Process by which the contents of a cell vacuole are released through fusion.

Question 41

What is antiponer?

Answer 41

When Na+ and k+ ions are pumped in different directions.

Question 42

What does ATP cause?

Answer 42

State changes.

Question 43

How much energy does 1 ATP have?

Answer 43

enough to pump 2Na+ and 3K+ ions in or out of a cell.