2.5 Biological Membranes Flashcards
(24 cards)
What are the roles of membranes within cells and at the surface of cells?
- Sites of chemical reactions
- Sites of cell communication
- Partially permeable barriers
which organelles have double membranes?
- Mitochondria
- Chloroplasts
- Nucleus
What is the Tonoplast?
Vacuole membrane
Definition of membrane?
Membranes are partially permeable barriers between the cell and its environment, between organelles and the cytoplasm, and within organelles
What is cell communication?
cell signalling is the process by which cells communicate with each other
Why is cell signalling important?
its very important as it allows multicellular organisms to control and coordinate their bodies and to respond to their environments
what is the charge of a phosphate group?
it is polar
slightly negative
why does a membrane have a mosaic pattern?
proteins are scattered throughout the membrane which makes it look like a mosaic
what is the movement of a phospholipid in a membrane like?
mainly move sideways through their own layers
what is a glycoprotein?
a carbohydrate chain attached to a protein molecule
what is glycocalyx?
very hydrophilic molecules on the outside of the membrane which attract water with dissolved solutes
what is useful about glycocalyx?
they help the cell interact with its watery environment and obtain dissolved substances
what is a glycolipid?
a carbohydrate chain attached to a lipid
what is a glycoprotein?
a carbohydrate chain attached to a protein
what in the makeup of a membrane affects its fluidity?
cholesterol
is membrane fluidity reversible?
yes, up to a certain point
what does active transport require?
ATP
metabolic energy
when an ion is trying to go through a carrier protein by active transport, what happens?
-the ion thats going to be transported binds to receptors on the carrier protein
-ATP binds to carrier protein and is hydrolysed into ADP and phosphate
-the phosphate and carrier protein binding causes the carrier protein to change shape
-this opens it up to the inside of the cell and ion is released into the cell
-phopshate released from the carrier protein and rejoins with the ADP to form ATP. the carrier protein returns to its original shape
which factors affect simple diffusion?
temperature and concentration
which factors affect membrane diffusion?
surface area
thickness of membrane
what is facilitated diffusion?
protein channels and carrier proteins
what kind of energy is used in diffusion?
kinetic energy
why is diffusion passive?
only requires kinetic energy
