Cell membrane and transport

What are the two main components of the membrane structure

Phospholipids and proteins

What do phospholipids consist of

A glycerol bonded to two fatty acids and a phosphate group

What does hydrophobic mean

Repel water and polar molecules

What does hydrophilic mean

Attracts water and polar molecules

What part of the phospholipid is hydrophobic

The tails (fatty acids)

What part of the phospholipid is hydrophilic

The heads (phosphate groups)

Define intrinsic protein

A protein that spans the membrane from one side to the other

Define extrinsic protein

A protein that is found in one side of the bilayer or on the surface of the bilayer

Define glycolipids

Short chain carbohydrates attached to phospholipids

Define glycoprotein

Short chain carbohydrates attached to proteins

Where is cholesterol in the membrane located

In the hydrophobic layer (tails)

What is the term for all the carbohydrates on the outer surface of a cell membrane

Glycocalyx

What is meant by fluid mosaic model

Fluid refers to the lateral movement of molecules in the membrane and the mosaic to the random pattern of proteins

Where did evidence for the fluid mosaic model come from

Freeze fracture electron microscopy

Define diffusion

Passive movement from high concentration to low concentration

What factors affect rate of diffusion

Temperature

Length of diffusion pathway

Steepness of concentration gradient

Surface area of the membrane

Define osmosis

The net movement of water from an area of high water potential to an area of low water potential across a selectively permeable membrane. Passive process

Define water potential

The tendency of water to leave a system by osmosis

What does water potential of solutions depend on?

Solute concentration (solute potential)

Pressure exerted on the solution (pressure potential)

What is a hypertonic solution

A solution with a lower solute concentration and therefore higher water potential

What is an isotonic solution

Solution that has the same concentration of solute and the same water potential

What is a hypertonic solution

A solution with a higher concentration of solute and a lower water potential

What is haemolysis

When water moves into a red blood cell by osmosis. The cell expands and then bursts due to the increased pressure in the cells

What is the equation of water potential for plant cells

Water potential= solute potential+pressure potential

When do plant cells become turgid

When immersed into solutions of higher water potential than the cell contents

Describe plasmolysis

When plant cell is placed in solution that has a water potential that is lower than the cell.

What is meant by incipient plasmolysis

When water potential of solution and tissue are equal

Define active transport

Move substances from low concentration to high concentration (against concentration gradient) requires ATP