bio membranes Flashcards
cell membranes?
gateway of the cell
-controls the exchange of materials
-site of chemical reactions
-site of cel signalling
Phospholipid
it forms by layers it has hydrophilic with the ball which is attraction to water and the tail is hydrophobic which means potion from water
Channel proteins
Forms a passage way so water and polar molecules can pass through by diffusion
carrier proteins
Change shape so they move substances from one side of the membrane to the other
Glycoprotein
They are proteins with a short carbohydrate attached that forms hydrogen bonds and stabilise the membrane structure. They also act as receptors for cell signalling for certain molecules and trigger specific changes in the cell.
Both glycolipids and glycol protein
They formed the surface antigens by which the immune system can identify the cell as belonging to the body
Cholesterol
It’s main function in the membrane is to maintain a suitable level of fluid fluidity. The cholesterol molecule has both hydrophilic and hydrophobic which allows cholesterol to bind to the phospholipid and prevents the membrane from being too fluid.
Factors affecting membrane structure and permeability
temperature and organic solvents
how does temperature affect membrane structure and permeability?
As the temperature rises, the lipid becomes more fluid which reduces its effectiveness as a barrier to polar molecules. It also causes proteins to denature which describes the membrane structure and the membrane can no longer act as an effective barrier.
how does organic solvent affect membrane structure and permeability?
organic solvents dissolve lipids and disrupt membrane structure leading to increase permeability, e.g. bleach
transport of substances in and out the cell
osmosis diffusion filiated diffusion and active transport
diffusion
Diffusion is the net movement of molecules from an area of high concentration to an area of low concentration. It’s a passive process and no energy required.
ficillated diffusion
Facilitated diffusion, assists large molecules to pass the membrane
small molecules and small polar molecules are transported by channel proteins which functions like it can be open or close to regulate flow
Large molecules use molecules which attach to the protein which then changes shape and transfers the molecule to the other side of the membrane
Active transport
Active transport is the process of net movement from a low concentration to a high concentration and is carried out by carrier proteins and ATP processes the energy
Osmosis
osmosis is the net movement of water molecules from a more dilute solution to a more concentrated solution across a partially permeable membrane.
Water potential
The measure of tendency of water to move from one area to another
osmosis moves from high water potential to low water potential
endocytisis
process by which cells absorbed molecules by engulfing them there are two forms of endocytisis
pinocytosis and phagocytosis
