Plasma Membranes Flashcards
What do plasma membranes do?
They act as a barrier between the extracellular environment and the cell, and are able to regulate what comes in and out of the cell
What is the structure of a phospholipid?
They have a phosphate head (hydrophilic/polar) and a fatty acid tail (hydrophobic/non-polar). They arrange themselves in a bilateral as seen below,
o= =o
o= =o
o= =o
o= =oHow is the phospholipid bilayer formed?
It forms naturally, with the water loving heads wanting to point outwards into the hydrophilic environment and the hydrophobic tails pointing inward as far away from water as possible
What are 3 other proteins that are found in the membrane?
Protein channel
Carrier protein
Receptor protein
Glycoprotein
Why is the plasma membrane described as a fluid mosaic?
It is fluid due to its constantly moving phospholipids and has an array of proteins sitting in the layer like a mosaic
What affects the plasma membranes fluidity?
Temp, presence of alcohols or detergents, type of fatty acid tails, cholesterol
What is active transport?
When substances are either brought into or secreted from a cell against the concentration gradient, which requires ATP
What is facilitated diffusion?
When specific proteins assist in the diffusion of substances across a semi permeable membrane that wouldn’t easily be able to pass through by simple diffusion. It requires no ATP
What is osmosis?
The net diffusion of free water molecules through a semi permeable membrane from a region of low solute to high solute concentration
What is bulk transport?
When large substances unable to diffuse through simple or facilitated diffusion are moved in or out of the cell by use of vesicles
What substances most easily diffuse across a membrane?
Small Non polar molecules
