Cell Transport Mechanisms

Study Notes

Active transport moves materials across cell membranes against their concentration gradients, from a region of lower concentration to a region of higher concentration.
Requires energy input, usually in the form of ATP.

Process of bringing liquids or large molecules into a cell by engulfing them in a membrane.
The cell membrane creates a pocket around the substance.
Can be subdivided into phagocytosis, pinocytosis, and receptor-mediated endocytosis.

A process of releasing substances from a cell by fusing membrane-bound vesicles with the plasma membrane.
Opposite of endocytosis.

"Cell eating"
The process by which large particles, like cells or large particles, are taken in by a cell.

A type of endocytosis where specific target molecules are captured by receptor proteins on the cell surface.
Receptors gather in regions of the plasma membrane called coated pits.

Series of reactions in the mitochondria that use energy to drive the production of ATP from ADP and phosphate.
Key steps include:
- Intermembrane space: contains H+ ions pumped across the inner mitochondrial membrane
- Inner mitochondrial membrane: Contains ADP + Pi, ATP synthase, H+ ions. ATP is created when H+ ions diffuse through the protein channel.
- Mitochondrial matrix: Contains the proton pump.

Lysosomal enzymes: Break down the vesicle membrane and its contents, releasing them into the cell.

Endoplasmic reticulum (ER): Produces transmembrane glycoproteins and secretory proteins.
Secretory protein: A protein that will be released from the cell.
Glycolipid: A lipid with a carbohydrate attached.
Golgi apparatus: Modifies and packages proteins and lipids.
Vesicle: A membrane-bound sac that transports substances within the cell.
Plasma membrane: The outer layer of the cell.
- Cytoplasmic face: The side of the membrane facing the inside of the cell.
- Extracellular face: The side of the membrane facing the outside of the cell.
Secreted protein: Exiting the cell as a result of exocytosis.
Transmembrane glycoprotein: Embedded in the plasma membrane.
Membrane glycolipid: Embedded in the plasma membrane.

Axon: The long part of a neuron that transmits signals.
Neurotransmitter released into synapse: Chemical messenger released from a neuron.
Neurotransmitter attached to receptor: Neurotransmitter binds to a receptor protein on the receiving cell.
Dendrite: The branch of a neuron that receives signals.
Neurotransmitter stored in vesicles: Stored in vesicles within the neuron.
Enzyme that destroys neurotransmitter: Breaks down neurotransmitters in the synapse.

Neuron: nerve cell
Endocytosis: Process in which the neuron takes in acetylcholine to be recycled.
Synaptic vesicles: Store neurotransmitters.
Exocytosis active zone: Area on the neuron membrane where exocytosis of acetylcholine occurs.
Acetylcholine receptors: On the muscle cell membrane, they bind to acetylcholine.
Muscle: Contains acetylcholine receptors, receives signals from the neuron.
Acetylcholine: Neurotransmitter released from the neuron into the synapse.
Neuropeptide modulators: Neurotransmitters that affect the activity of acetylcholine.

Endocytosis: Used for bringing nutrients and other substances into the cell.
Exocytosis: Used for releasing waste products, hormones, and other substances from the cell.
Exocytosis in the human body: The release neurotransmitters from neurons.
Endocytosis: A process used by white blood cells to engulf bacteria.