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

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

Conjugation:
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).

Aquaporins:
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.

Symport:
Two different ions are transported in the SAME direction.

Antiport:
Two different ions are transported in OPPOSITE directions.

Endocytosis:
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.

Pinocytosis:
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.

Exocytosis:
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

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