Transport Across Membranes 3.2 Flashcards
(30 cards)
What is glycerol?
An alcohol with three carbon atoms, each linked to an OH group.
What are the main groups of lipids?
Triglycerides and phospholipids.
What is the R group on a fatty acid?
A variable hydrocarbon tail.
What are the two kinds of fatty acid?
Saturated and unsaturated.
What does a cell surface membrane form?
A semi-permeable boundary between the cell cytoplasm and the external environment.
What happens if you shake phospholipids in water?
They arrange themselves to become micelles.
What does the fluid mosaic model describe?
The arrangement of molecules within the phospholipid bilayer.
What is the function of cholesterol?
It helps to maintain the cell membranes shape and stabilityby restricting the movement of phospholipids.
How do cholesterol restrict the movement of phospholipids?
They bind to the hydrophobic tails of the phospholipids to hol them close together.
What do channel and carrier proteins do?
These help transport substances, such as
ions, sugars and amino acids, that cannot
diffuse across the membrane but are still
vital to a cell’s functioning.
What is the function of peripheral proteins?
They act as receptors for hormones or neurotransmitters or are involved in cell recognition.
How does a temperature below 0 degrees celsius impact the cell membrane?
The phospholipids don’t move much due to low energy, the carrier proteins freeze and it causes the permeability to decrease.
How does a temperature above 45 degrees celsius impact the cell membrane?
The bilayer starts to melt, which makes the membrane more permeable. The water in the cell also starts to expand and puts pressure on the membrane. Also the carrier proteins denature so they can’t control what enters and leaves the cell.
What is simple diffusion?
A passive process involving the net movement of particles from a high to a low concentration.
What makes a molecule easier and quicker to diffuse?
Being smaller and having a lower polarity.
What type of particles can not diffuse across a membrane?
Charged particles.
What are the key factors impacting the rate of diffusion?
Concentration, temperature, diffusion pathway(thickness of diffusion surface) and surface area.
What does Fick’s Law state?
The rate of diffusion is proportional to surface area x difference in concentration all over the length of the diffusion pathway.
What is facilitated diffusion?
A passive process which includes the use of carrier or channel proteins to facilitate the movement of large or charged particles.
What do channel proteins do?
Facilitate the diffusion of charged particles.
What do carrier proteins do?
To faciliate the diffusion of large molecules by allowing them to attach and change shape to be released on the other side.
What factors affect facilitated diffusion?
When the concentration gradient reaches equilibirum, facilitated diffusion slows down. The number of channel and carrier proteins.
What is the definition of osmosis?
The net movement of water molecules across a partially permeable membrane from an area of high water potential to an aera of low water potential.
What is water potential?
Water potential is the potentinal of a water molecule to diffuse in or out of a solution.
