2.5 biological membranes definitions Flashcards
Active transport
The active movement of substances (all types of molecules through carrier proteins) from an area of low concentration to an area of higher concentration up a concentration gradient with the use of energy in the form of ATP. (active)
Amphipathic
A molecule with both hydrophobic and hydrophilic parts.
Cell lysis
The bursting of a cell, particularly after the uptake of too much water into an animal cell through osmosis
Cholesterol
A mostly hydrophobic molecule that sits in the hydrophobic portion of the membrane and regulates membrane fluidity
Crenation
The shrinking of a cell when placed in a hypertonic solution due to large amounts of water moving out of the cell through osmosis.
Endocytosis
The bulk uptake of substances into a cell by invagination of the membrane to form a vesicle trapping the substances inside the cell with the use of energy in the form of ATP. (active)
Exocytosis
The bulk transport of substances out of a cell using a vesicle that fuses with the plasma membrane using energy in the form of ATP (active)
Facilitated diffusion
The net movement of substances (polar molecules, charged and water soluble molecules) from a high concentration to a lower concentration down their concentration gradient through transport/channel proteins without the use of energy. (passive)
Fluid mosaic model
A model that describes membrane structure as a sea of mobile phospholipids studded with various proteins
Hydrophilic
A molecule which is attracted to water.
Hydrophobic
A molecule which repels water
Integral membrane protein
A type of protein bound to the membrane with strong
interactions.
Osmosis
The net movement of water molecules across a partially permeable membrane from a region of high water potential to a region of lower water potential without the use of energy. (passive)
or
Diffusion of water molecules from an area of low solute concentration to an area of high solute concentration through a partially permeable membrane.
Peripheral membrane protein
A type of protein that is weakly bound to the surface of the membrane
Phagocytosis
The ingestion of solid material (particularly pathogens and foreign material) by phagocytic cells.
Phospholipid
A type of lipid formed by the condensation of one molecule of glycerol, two molecules of fatty acid and a phosphate group
Pinocytosis
The bulk uptake of liquids into the cell using energy in the form of ATP.
Plasmolysis
The effect produced by placing plant cells in a hypertonic solution causing the cell to shrivel from water loss, resulting in the membrane pulling away from the rigid cell wall.
Simple diffusion
The spreading out of substances from a high concentration to a lower concentration (down their concentration gradient) without the use of energy.
Turgid
A term used to describe a cell that is swollen due to large amounts of fluid uptake
Water potential
A measure of the tendency of water molecules to move from one area to another measured in kilopascals (kPa) and given the symbol Ψ
Diffusion in the phospholipid bilayer
passive movement of small, non-polar lipid soluble molecules such as carbon dioxide and oxygen from an area of high concentration to an area of low concentration. The molecules move directly through the phospholipid bilayer.
why is it called the fluid mosiac model
The fluidity of the membrane and the mosaic
arrangement of the proteins give the structure of
the membrane its name
The rate of gas exchange by diffusion becomes more rapid when what 3 things occur?
- Surface area increases
- Diffusion distance decreases
- Diffusion gradient becomes more steep
The movement of molecules through cell membrane depends on the properties of the molecule as well as the requirements of the cell. What are the types of movement?
Diffusion Facilitated Diffusion Osmosis Active Transport Endocytosis Exocytosis Bulk Transport
main function of the phospholipid bilayer (cell membrane)
controlling the movement of substances in and out of the cell/organelle. However, it also contains receptors for other molecules such as hormones and enables adjacent cells to stick together
