Sac 1 Unit 1 Biology VCE : Diffusion SAC

Osmosis

Net movement of free moving water molecules across a partially permeable membrane from an area of high water concentration to low water concentration ; this process is an example of passive transport

Diffusion

Net movement of a molecules from an area of high concentration to an area of lower concentration; this process is an example of passive transport

Hypertonic

More solute outside the cell, so water moves out to balance. Cell shrinks (crenation in animal cells, plasmolysis in plant cells).

Hypotonic

More solute inside the cell, so water moves in to balance. Cell swells & may burst (lysis in animal cells, turgid in plant cells).

Isotonic

same amount of water in and out of the cell

Turgid

Distended or swollen, especially due to high fluid content

Flaccid

Weak, limp

Lipids

General term for Fats, Oils and Waxes. Has little affinity for water. Fats and Waxes are generally solid at room temp, oils are liquid at room temp

Phospholipids

Have 2 fatty acids attached to a glycerol. Have a phosphate group attached to the glycerol and other small groups attached to the phosphate

Fatty acids

The sub-units of fats, oils and waxes

function of glycolipid

a protein that has carbohydrate chains attached to it, helping with cell recognition, signaling, and immune responses.

function of cholesterol

• Maintains membrane fluidity.

• Prevents the membrane from becoming too rigid in the cold or too fluid in the heat.

• Keeps the membrane stable and flexible.

small cells SA:V

Smaller cells have a higher SA:V ratio, which is generally advantageous for efficient exchange of materials .

large cells SA:V

Larger cells have a lower SA:V ratio, which can limit their ability to transport substances effectively . 

active transport

-Movement of molecules from low to high concentration (against the gradient).

-Requires energy (ATP)

-Requires a specific carrier protein

how does facilitated diffusion happen?

1. Molecules move from an area of high concentration to an area of low concentration. 

2. Carrier proteins bind to the molecules to be transported. 

3. The carrier proteins change shape, allowing the molecules to pass through the membrane. 

4. The molecules are released on the other side of the membrane. 

facilitated diffusion

Movement of molecules from high to low concentration using protein channels. This is an example of passive transport.