Cell membrane Flashcards
Whats the model used for cell membrane
The fluid Mosaic Model
Why is it ‘Fluid’
Proteins and lipids able to move around in the membrane
What are phospholipids made of
Type of lipid made from 2 fatty acid chains, Hydrophilic head, Hydrophobic tails
Why is it ‘Mosaic’
Because of Mosaic like make up of the components within the membrane
What two structures do phospholipids form
A micelle (circle) or a bilayer (rectangle)
What is the role of phospholipids
Barrior to most substances, helps control what enters/exits cell
What does size and polar do to affect diffusion across molecule
Smaller, less polar molecules diffuse easier and faster, it diffuses across the cell membrane
How do small polar molecules diffuse?
Diffuse across membrane, but slower (Water, urea)
How do charged particles (Ions diffuse)
Unlikely to diffuse across membrane
What is cholesterol?
Type of lipid - Formula is C27H46O
What does cholesterol do?
Controls membrane fluidity, More cholesterol = Less fluid = Less permeable. Keeps membranes stable at normal body temperature so cells dont burst open.
What amount of mass of the cell membrane do proteins make up?
45% but can vary from 25% to 75% depending on cell
Whats the span of an integral protein
Whole width of membrane
Where are peripheral (Or extrinsic) proteins located
Confined to inner or outer surface of membrane
What is a protein with a carbohydrate chain attached called
Glycoprotein
What are many integral proteins
Carrier Molecules or channels
What do channel proteins do
Help transport substances that cannot diffuse across the membrane, that are vital to cells functioning (Ions, sugars, amino acids)
What do other integral proteins do
Receptors for hormones and neurotransmitters, or enzymes for catalyzing reactions.
What to peripheral proteins on extracellular side of membrane do
Act as receptors for hormones or neurotransmitters, or are involved in cell recognition. Many are glycoproteins.
What do peripheral proteins on cytosolic side of the membrane do
involved in cell signalling or chemical reactions. Can dissociate from membrane and move into the cytoplasm
Why is it important a cell membrane fluid
Cell would not be able to function
What processes are fluid membrane needed for
Diffusion of substances across the membrane, Membranes to fuse, cells to move and change shape
