Membranes

Question 1

What is compartmentalisation?

Answer 1

Separation of organelles and areas of cells via membranes

Question 2

What is the plasma membrane?

Answer 2

A basic structure that separates the cell from its external environment

Question 3

What is the phospholipid bilayer?

Answer 3

Hydrophilic phosphate group heads and hydrophobic fatty acid tails that form the plasma membrane

Question 4

What is the fluid mosaic model?

Answer 4

A model presented of plasma membranes that shows proteins incorporated intrinsically and extrinsically

Question 5

What are membrane proteins?

Answer 5

Proteins in the plasma membrane that are either intrinsic and extrinsic

Question 6

What are intrinsic proteins?

Answer 6

Proteins that are embedded through both layers of the plasma membrane and come in two types; carrier and channel

Question 7

What are channel proteins?

Answer 7

Proteins that have a hydrophilic channel and allow passive movement for polar molecules and ions

Question 8

What are carrier proteins?

Answer 8

Proteins that have a role in passive and active transport and often changes the shape of the protein

Question 9

What are glycoproteins?

Answer 9

Intrinsic proteins embedded with carbohydrate chains with varying lengths and sizes, they play a role in adhesion and cell signaling (neurotransmitters, peptide hormones (insulin, glucagon))

Question 10

What is cell signaling?

Answer 10

When a chemical binds and elicits a cascade response inside the cell

Question 11

What are glycolipids?

Answer 11

Extrinsic lipids with attached carbohydrate chains that act as cell markers and antigens

Question 12

What are extrinsic proteins?

Answer 12

Proteins that are on one side of the plasma membrane

Question 13

What are the roles of the plasma membrane?

Answer 13

Environment, transport, cell to cell signaling, detecting changes in the environment, site of chemical changes, pseudopodia, anchorage for the cytoskeleton, cell to cell joining

Question 14

How does the plasma membrane effect the environment?

Answer 14

Maintains a fixed set of conditions inside the cell

Question 15

How does the plasma membrane effect transport?

Answer 15

Provides a partially permeable membrane to control which substances enter and exit the cell

Question 16

How does the plasma membrane effect cell to cell signaling?

Answer 16

Have either glycoproteins or lipoproteins to interact between cells

Question 17

How does the plasma membrane effect detection of environment changes?

Answer 17

Signal transduction- so having proteins that can act as receptors for hormones

Question 18

How does the plasma membrane effect chemical reactions?

Answer 18

Proteins in the membranes may act as enzymes

Question 19

What is pseudopodia?

Answer 19

When plasma membranes are used for feeding and movement in single celled organisms like amobea

Question 20

How does cholesterol effect the plasma membrane?

Answer 20

Maintains stability and fluidity

Question 21

What is an amphipathic molecule? Give two examples

Answer 21

A molecule with hydrophilic and hydrophobic regions, phospholipids and cholesterol

Question 22

How does cholesterol effect the fluidity of the plasma membrane?

Answer 22

It reduces the fluidity by filling the gaps when the fatty acid tail bends more and therefore prevents crystallisation

Question 23

What are the components in the plasma membrane?

Answer 23

Phospholipids, channel proteins, carrier proteins, glycoproteins, peripheral proteins, cholesterol

Question 24

What are the structural properties of the phospholipid bilayer?

Answer 24

7.5 nanometres thick, held by weak hydrophobic interactions, have hydrophobic and hydrophilic layers that restrict entry and exit, allow for membrane fluidity,

Question 25

What are the roles of intrinsic proteins?

Answer 25

Passive and active transport, active transport often includes a change in shape

Question 26

What are the roles of extrinsic proteins?

Answer 26

Acting as receptors

Question 27

What are the roles of intrinsic glycoproteins?

Answer 27

Cell signaling

Question 28

What are the roles of intrinsic channel proteins?

Answer 28

Passive movement and diffusion of polar molecules and ions

Question 29

What is active transport?

Answer 29

Movement of molecules or ions into our out of a cell from a region of a lower concentration to a region of a higher concentration

Question 30

What is osmosis?

Answer 30

The diffusion of water across a partially permeable membrane

Question 31

What is diffusion?

Answer 31

Net movement from a region of a higher concentration to a region with a lower concentration

Question 32

What is a facilitated diffusion?

Answer 32

Movement down gradient across a membrane through protein channels

Question 33

What is bulk transport?

Answer 33

Active movement of large molecules

Question 34

How does temperature affect diffusion rate?

Answer 34

Increases rate due to an increase of kinetic energy

Question 35

How does concentration gradient affect diffusion rate?

Answer 35

Increases rate due to the increase of substances to be diffused

Question 36

How does surface area affect diffusion rate?

Answer 36

Increases the rate due to greater area to diffuse across

Question 37

How does membrane thickness affect diffusion rate?

Answer 37

An increase of membrane thickness decreases the rate of diffusion due to the greater distance to diffuse across

Question 38

What is facilitated diffusion?

Answer 38

The passive movement of molecules across the cell membrane via the aid of a membrane protein

Question 39

How does facilitated diffusion work?

Answer 39

Used by molecules that are unable to cross the phospholipid bilayer (large molecules, ions) and is mediated by two types of intrinsic proteins, carrier and channel

Question 40

How do solvents affect membrane structure?

Answer 40

Solvents dissolve the phospholipids which disrupts the membrane and causes it to be leaky

Question 41

How does temperature affect the membrane structure?

Answer 41

The increase in temperature increases the kinetic energy, which causes the phospholipid fatty acid tails to vibrate more, which disrupts the membrane

Question 42

Describe active transport

Answer 42

1 - Molecule or ion binds to receptor 2 - On the inside of the cell, ATP binds to the carrier protein 3 - This causes the protein to change shape 4 - Molecule or ion is transported into the cell 5 - The leftover phosphate molecule reforms ATP from ADP 6 - Carrier protein returns to old shape

Question 43

What is water potential?

Answer 43

Pressure exerted by water molecules colliding with sides in kPa