Transport Across Membranes

HideShow resource information
  • Created by: yott33
  • Created on: 29-03-16 20:23
Define Diffusion
Diffusion is the net movement of atoms or molecules from an area of high concentration to an area of low concentration
1 of 23
What sort of process is diffusion?
Passive, meaning no energy is required.
2 of 23
Describe diffusion in solids, liquids and gases
Solids: little diffusion because no movement, liquids & gases: much more diffusion because particles are free to move anywhere
3 of 23
What does Facilitated Diffusion do?
It assists larger molecules, polar molecules and ions to pass through the membrane.
4 of 23
How does this occur?
Uses proteins in the membrane - either carrier or channel. Ions & small polar molecules use channel proteins. Larger molecules use carrier proteins that are specific to the substance.
5 of 23
How do the carrier proteins work?
The molecule attaches to the protein which then changes shape. This transfers the molecule to the other side.
6 of 23
Does Active Transport require energy?
Yes, because particles cannot pass passively up a concentration gradient.
7 of 23
How is it carried out?
Uses carrier proteins. ATP provides the energy. Each carrier is specific. Some do two-way active transport, pumping one substance into the cell and another out at the same time.
8 of 23
Define Osmosis
Osmosis is the net movement of water molecules from a dilute solution to a concentrated solution across a partially permeable membrane.
9 of 23
How is osmosis different from diffusion & active transport?
It's water molecules only. It's through a partially permeable membrane.
10 of 23
How do you refer to the concentration of water?
Water potential
11 of 23
If the water potential is higher than an animal cell, what happens?
Too much water diffuses into the cell and it BURSTS
12 of 23
If the water potential is equal to an animal cell, what happens?
Nothing
13 of 23
If the water potential is lower than an animal cell, what happens?
Too much water diffuses out of the cell and it becomes CRENATED
14 of 23
If the water potential is higher than a plant cell, what happens?
Too much water diffuses into the cell and it is TURGID
15 of 23
If the water potential is equal to a plant cell, what happens?
Nothing
16 of 23
If the water potential is lower than a plant cell, what happens?
Too much water diffuses out of the cell and it becomes PLASMOLYSED
17 of 23
What is endocytosis?
The process by which cells absorb molecules by engulfing them.
18 of 23
What two forms of endocytosis are there?
Phagocytosis and Pinocytosis
19 of 23
Describe Phagocytosis
Protrusions called pseudopodia extend from the cell and wrap themselves around a larger particle. The membrane fuses to seal the particle into a vesicle.
20 of 23
Describe Pinocytosis
The plasma membrane invaginates inwards, allowing the molecules in, then the membrane fuses around the molecules to form a vesicle.
21 of 23
What is exocytosis?
The process where substances are secreted and from a cell.
22 of 23
How does it occur?
It is a reversal of pinocytosis, so the vesicle containing the particles reaches the membrane which then parts, allowing the substance out.
23 of 23

Other cards in this set

Card 2

Front

What sort of process is diffusion?

Back

Passive, meaning no energy is required.

Card 3

Front

Describe diffusion in solids, liquids and gases

Back

Preview of the front of card 3

Card 4

Front

What does Facilitated Diffusion do?

Back

Preview of the front of card 4

Card 5

Front

How does this occur?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cellular processes resources »