Cell Vocabulary

Semi-Permeable Phospholipid Bilayer

Semi-Permeable Phospholipid Bilayer

A semipermeable membrane created by all biological organisms.

It can let certain things into and out of the cell.

This membrane is made up of a bilayer of phospholipids.

Also contains proteins and cholesterol.

Is curved and very fluid/flexible.

Phospholipids

Main structural components of membranes. They have two parts, a hydrophilic head, and a hydrophobic tail.

The heads face outwards and the tails face inwards.

Protein Channels/Tunnels

Specialized areas where larger molecules can get through into the cell.

Protein Receptors

Serves are communication for cells and detects the outside world. For example, if the skin gets cut, these receptors will identify and single towards it.

Intracellular

Something located within the cell

Intercellular

Something located outside the cell

Diffusion

A process where molecules move from a region of high concentration to a region of lower concentration.

Once this goes on a bit, the area will reach an equilibrium where the net movement is zero.

Concentration Gradient

The difference between concentration on either side of the membrane.

Passive Transport

Requires NO energy and moves with the concentration gradient. Has two types, simple and facilitated diffusion.

Simple Diffusion

Small molecules slip through the membrane. Goes with the concentration gradient.

Facilitated Diffusion

Larger molecules are too large to fit through the membrane. They use carrier proteins which are protein channels/tunnels.

Active Transport

Large/large groups of molecules that go against the concentration gradient. Uses energy. There are two ‘categories‘, protein pumps and bulk transport.

Protein Pump

Specific.

Pumps ions across the membrane which goes against their concentration gradient. This requires energy and it changes the shape.

Bulk Transport

Large molecules being carried across the membrane and this has three distinct types.

Endocytosis

A type of bulk transport.

Bringing material IN by folding the membrane within itself. In this, there are two kinds:

Phagocytosis → cell eating; takes in solids

Pinocytosis → cell drinking; takes in liquids

Exocytosis

A type of bulk transport.

Getting stuff like waste out of the cell. This happens through a ‘pinching’ motion.

Contractile Vacuole

A type of bulk transport.

Found mostly in single celled aquatic organisms.

Used to remove excess water from a cell kinda like how a sponge squeezes out water.

Osmosis

The process by which water moves across the membrane via diffusion.

Water will keep hitting itself against the membrane and bouncing off until it can finally penetrate.

Hypotonic Solution

Freshwater is an example.

Has a higher concentration(more pure) outside. Water moves in.

Animal cell → As water rushes in, the animal cell will burst. This is called ‘cytolysis‘ meaning ‘cell breaking‘

Plant cell → The plant cell will not burst but swell due to its cell wall. This overinflation is known as being ‘turgid’

Hypertonic Solution

Has a lower concentration(less pure) outside. Water moves out.

Animal cell → As water leaves, the animal cell will shrink. This is known as being ‘crenated‘

Plant cell → The plant cell will not lose its shape due to its cell wall; the cell membrane pulls away from the wall. This is described as ‘plasmolysis’

Isotonic

Both solutions(the solute and surrounding area) have the same level of concentration. They’re at equilibrium.