Topic 4 - Cell Membranes and Transport Flashcards
What is Active Transport?
The active movement of substances from a low concentration to a high concentration, against a concentration gradient, with the use of ATP
What is an Antigen?
A marker molecule on a cell membrance (usually a protein or glycoprotein) that can be detected by antibiotics + triggers an immune response
What is a Carrier Protein?
Protein involved in active transport that uses energy from ATP to change conformation.
What is Cell Signalling?
When cells release chemicals which bind to complementary receptors on their target and trigger an immune response.
What is a Cell Surface Receptor?
A component on the cell membrane which binds to extracellular signals.
What are Channel Proteins?
Transmembrane non-polar proteins - transport large / charged substances - can do faciliated diffusion or active transport.
What is Cholesterol?
A steroid hormone which adds stability to phospholipid bilayer - contains only Carbon, Hydrogen, and one oxygen atom.
What is Diffusion?
The movement of substances from a high concentration to a lower concentration, along a concentration gradient - doesn’t require energy.
What is Endocytosis?
A method of bulk transport into a cell - relies on invagination of cell membrane, and requires ATP.
What is Exocytosis?
A method of bulk tranport out of a cell - vesicles fuse with cell membrane and release contents - requires ATP.
What is Facilitated Diffusion?
The passive movement of substances from a high concentration to a low concentration (along concentration gradient) through transport proteins, without using energy.
What is the Fluid Mosaic Model?
A model that describes membrane structures as a sea of mobile phospholipids studded with variously shaped proteins.
What is a Glycolipid?
A lipid which is bonded to a monosaccharide
What is a Glycoprotein?
A protein which is bonded to a carbohydrate chain
What is Osmosis?
The passive movement of water from a region of high water potential to a region of low water potential, along a concentration gradient - no ATP required.
What is Passive Transport?
The movement of substances without the use of energy.
What is a Phospholid?
Type of lipid that forms the cell surface membrane bilayer
How is a phospholipid formed?
The condensation of one glycerol molecule, two fatty acid molecules, and a phosphate molecule.
How is a phospholipid arranged?
Two fatty acid chains are the non-polar hydrophobic tails whilst the phosphate group is the polar hydrophilic head.
What is a Phospholipid Bilayer?
Polar membrane made of two layers of phospholipids, that is a selectively permeable barrier to the passage of ions into and out of the cell.
What is Surface Area : Volume ratio?
Volume of an object compared with it’s surface area - the smaller the organism, the higher it’s SA:V ratio.
What is Water Potential?
A measure of the tendency of water molecules to move from one area to another measured in kPa and given a the greek letter psi ‘ψ’
