CH2/3 ozmosis, diffusion and transport through the membrane Flashcards
what is diffusion?
- the movement of molecules down the concentration gradient
- non polar and small molecules can freely diffuse across the plasma membrane
why can water molecules move through the plasma membrane even though they are hydrophilic?
they pass through the membrane through special proteins called aquaporins
what is tonicity?
the measure of the relative concentrationof solutes one either side of the plasma membrane
why is protein mediated active transport needed?
for when there is a difference in concentration gradients of the substances inside and outside of the cell
what does against the gradient need?
- energy (ATP)
- membrane proteins
as it helps substances through
what is facillitated diffusion?
it is a type of passive transport where molecules move through a phospholipid bilayer with the aid of a membrane protein
what is simple diffusion?
the passive movement of molecules from areas of high concentration to areas of low concentration (down the concentration gradient)
what is ozmosis?
the passive transport of a solvent (typically water) through a semi permeable membrane from a region of low solute to a region of high solute.
what does hypertonic mean?
a solution with a higher concentration compared to another solution
what does isotonic mean?
a solution with the same solute concentration when compared to another solution
what does hypotonic mean?
a solution with a lower concentration when compared to another solution
what are the elements of the plasma membrane and what do they do?
- cholesterol - regulates fluidity
- phospholipids - form the bilayer
- glycoproteins - antenna that repel/release bacteria
- a protein bound to a carbohydrate - peripheral proteins - communication
- a protein that is temporarily attached to the plasma membrane - channel protein - pore - watermolecules or small ions pass through
- carrier protein - transfer solutes across lipid bilayer by undergoing conformational changes
what are the 3 types of proteins?
Integral protein – proteins that are a permanent part of the
membrane
Transmembrane protein – integral proteins that span the entire bilayer
**Peripheral protein **– are temporarily attached to the
plasma membrane
what is a carrier protein?
- attatch to a substancethat is being transported
- undergoes conformational change to push substance down the concentration gradient
what is a protein channel?
- pores or holes in the membrane
- help move water molecules or small ions down their concentration gradient in or out of the cell
what are phospholipids?
- maintains integrity and fluidity of cell membrane
- the main component of the plasma membrane
- ## hydrophyllic head/ hydrophobic tail
amphipathic
a molecule with both hydrophobic and hydrophyllic components
e.g phospholipid
plasma membrane
- semi permeable membrane
- controls what enters and exits the cell
- made up of phospholipids and has many molecules embedded in it
what is passive transport?
the movement of molecules through a semipermeable membrane and down the concentration gradient without the input of energy
- no ATP
what is the function of the plasma membrane?
it controls what can enter and exit the cell
what is active transport?
movement of molecules across a semipermeable membrane that requires energy
- uses ATP
- used AGAINST the concentration gradient
what does ATP stand for?
adenosine triphosphate
what is exocytosis?
moves large substances out of the cell
what is endocytosis?
moves large substancesinto a cell
extra cellular?
outside the cell
intracellular?
inside the cell
solute?
a substance dissolved in solvent
solution?
a liquid in which a solute is dissolved in a solvent, forming a solution
solvent?
The term ‘solvent’ can be defined as a substance that has the ability to dissolve a given solute to form a solution with it.
