Transport across cell membranes Flashcards
What structure do plasma membranes have?
It is like a fluid mosaic model due to the mixture and movement of the phospholipids, proteins, glycoproteins, and glycolipids.
How are the molecules arranged within the cell membrane?
They are arranged within the phospholipids molecules that create the partially permeable membrane.
How are the phospholipids arranged?
The phospholipids align as a bilayer due to the hydrophobic heads being attracted to water and the hydrophilic heads being repelled by water.
How is cholesterol involved as a component of the cell membrane?
Cholesterol is present in some membranes too and will restrict the lateral movement of other molecules in the membrane. Also, it helps the membrane have less fluid at high temperatures and prevents water and dissolved ions from leaking out of the cell.
How are proteins involved as a component of the cell membrane?
Proteins are embedded across the cell membrane either peripheral or integral.
What is the function of peripheral and integral proteins?
The peripheral proteins provide mechanical support, or they are connected to proteins or lipids to make glycoproteins or glycolipids. The function of these is as cell recognition, as receptors.
The integral proteins act as protein carriers to carry molecules across the membrane.
Explain the function of integral proteins.
Protein channels form tubes full of w/water to let water ions diffuse through, whereas the carrier proteins will change shape and bind to others and let large molecules such as glucose and amino acids pass through by changing shape.
What is simple diffusion?
A passive process is a movement of particles from an area of high concentration to an area of low concentration. This is necessary for small important molecules such as oxygen ( needed for metabolism ) and carbon dioxide ( needed to be expelled for eventual release in the environment ).
What is facilitated diffusion?
Transport of material across the cell membrane via membrane proteins embedded in the cell. This type of transport is important for moving large polar molecules and ions that cannot diffuse through simple diffusion, either through a channel protein or a carrier protein.
What is osmosis?
Type of transport where water molecules diffuse through a membrane down a concentration gradient. In the process of transport, the concentration of both sides of the membrane is equal.
What is co-transport?
This is a specific type of active transport where two substances are simultaneously transported across a membrane through a symporter.
What is a symporter?
Proteins that simultaneously transport two molecules across a membrane in the same direction.
