b2.1 (ai generated notes)

Question 1

What is simple diffusion based on?

Answer 1

The size and hydrophobic/hydrophilic nature of molecules.

Question 2

What do channel proteins do?

Answer 2

Facilitate movement down a concentration gradient.

Question 3

What is active transport?

Answer 3

The movement of molecules against a concentration gradient using energy.

Question 4

Define Osmosis.

Answer 4

The diffusion of water across a selectively permeable membrane from a solution of higher concentration to a lower concentration.

Question 5

How is osmosis different from diffusion?

Answer 5

Osmosis only occurs across a membrane and involves the diffusion of water.

Question 6

What type of substances are membranes impermeable to during osmosis?

Answer 6

Large polar substances.

Question 7

What creates the regions of different solute concentrations across a membrane?

Answer 7

The impermeability of membranes to large polar substances.

Question 8

Outline the structure of aquaporins.

Answer 8

Integral proteins composed of 4 monomeric subunits, each with a water channel lined with hydrophilic side chains.

Question 9

What is the function of aquaporins?

Answer 9

Allow water to flow through the membrane while preventing ions.

Question 10

Why are the channels within aquaporins hydrophilic?

Answer 10

To allow water to pass through the hydrophobic lipid bilayer.

Question 11

How does facilitated diffusion differ from simple diffusion?

Answer 11

Facilitated diffusion requires carrier/channel proteins for solute movement.

Question 12

What is the difference between passive and active transport?

Answer 12

Passive transport requires no energy and moves substances from high to low concentration; active transport requires energy and moves substances from low to high concentration.

Question 13

Define active transport.

Answer 13

The movement of molecules against a concentration gradient, requiring energy from ATP.

Question 14

What is direct active transport?

Answer 14

Transport where energy is released by an exergonic reaction to move molecules across membranes.

Question 15

What is indirect active transport?

Answer 15

Movement of one solute down its concentration gradient driving the movement of a second solute against its gradient.

Question 16

Give examples of when active transport is used.

Answer 16

• Uptake of glucose
• Removal of waste materials
• Maintenance of ion concentrations in cells
• Uptake of mineral ions in roots.

Question 17

What additional components do most membranes contain?

Answer 17

Carbohydrates, in addition to phospholipids and proteins.

Question 18

What are glycolipids?

Answer 18

Carbohydrates covalently bound to lipids in the cell membrane.

Question 19

What are the two classifications of glycolipids?

Answer 19

• Glycoglycerolipids
• Glycosphingolipids.

Question 20

What is the glycocalyx?

Answer 20

The sticky layer formed by carbohydrate groups of glycolipids and glycoproteins that protrude from the cell surface.

Question 21

What role does the glycocalyx play?

Answer 21

IT IS THE LAYER OR GLYCOPROTEINS ANFD GLYCOLIPIDS
*
* * Cell signaling
* Cell adhesion
* Cell-cell recognition
* Protection of the cell surface.

Question 22

What does the Fluid Mosaic Model state about the lipid bilayer?

Answer 22

It is fluid, and its fluidity depends on the nature of fatty acids and cholesterol.

Question 23

What do integral and peripheral proteins contribute to?

Answer 23

The mosaic nature of the lipid bilayer.

Question 24

Where are carbohydrates located in the membrane?

Answer 24

On the extracellular side of the membrane, playing a role in cell recognition.