Concentration Gradient:
When the concentration is larger or smaller on one side of a membrane than the other side.

Passive (No Energy):
From High Concentration to Low Concentration
Ex. Water can go through in small amounts.

Active (Require Energy):
From Low Concentration to High Concentration

Uses NO energy and NO proteins, and move around randomly.
Molecules will move from high to low, AKA with their gradient.

How bacteria share their plasmid DNA.

Hydrophilic substances like Large polar molecules CAN NOT freely come through the membrane.
This DOES NOT require ATP it is 100% Passive (goes along gradient).

Channel Proteins:
A hydrophilic tunnel that allows specific target molecules to enter

Carrier Proteins:
Changes shape to move molecules to one side (Ex. Natrium-Kalium Pump).

Large amounts of water move through these proteins, rather than simple diffusion.

Ions NEED channel or carrier proteins.

Active Transport:
Transport that requires energy, because the molecules get PUMPED, instead of moving as they normally would.

Primary Active Transport:
Directly uses ATP to open a carrier protein ONLY.

Functions of active transport:

  • They create and maintain Concentration gradients, by moving things to places they shouldn’t be.
  • They need ATP and they “create” ADP and a loose P “refilling” in the mitochondria.

Electrochemical gradient (membrane potential / polarization):
This happens to a membrane, because of the number of ions on one side compared to the other one.
And some ions are positive and some are negative, which also has an effect.
The Natrium-Kalium Pump CREATES the electrochemical gradient, it DOES NOT use it.

Secondary Active Transport (Cotransport):
Uses energy from electrochemical gradient to transport TWO different ions across the membrane.

Two different ions are transported in the SAME direction.

Two different ions are transported in OPPOSITE directions.

A cell that folds its membrane around other cells (usually bacteria), and then puts them into a bubble called a Phagosome and then destroys it, this is most commonly used by White Blood Cells.
The Phagosome will then connect with a Lysosome which will digest the bacteria with enzymes.
It takes energy (ATP).

Phagocytosis (Ex. Lysosomes):
Big particles like pathogens are taken in by the membrane, usually to be destroyed.

The cell takes in some of the extracellular fluid, which contains dissolved substances like ions.

Receptor-Mediated Endocytosis:
The membranes receptors are used to capture target molecules and are then brought into the cell.

Releasing molecules basically.
This is used primarily between Neurons when a neuron releases neuro-transmitters to the other neuron.
Vesicles basically use energy to fuse into the membrane and release waste, proteins, etc.

The middle lamella:
The space between plant cells.

Wood is so rigid though:
After a long time, the plant cell can create a second cell wall, which is why some plants are very hard and robust

Small holes in the plant cell wall, that allows for the transfer of molecules like sugar