Biology 2:cells - diffusion and fluid mosaic model Flashcards
what does the lysosome membrane do
keep enzymes that could damage the cell isolated form cytoplasm
what does the nuclear membrane do 3 things
isolates DNA and chromosomes from the membrane
entry and exit point ts for hormone molecules that cn affect genes
exit points for mrna
what is the fluid mosaic model
membranes are made up of a phospholipid bilayer with various molecules floating around in it
name all 7 of the molecules in the fluid mosaic model
phospholipid bilayer
surface proteins
protein channels
carrier proteins
cholesterol
glycolipid
glycoprotein
What is the function of the phospholipid(3 things)
allows lipid soluble molecules to pass
prevents water souluable molecules form entering and leaving
gives membrane flexibility
What is the function of the surface proteins(3 things)
gives the membrane mechanical support
uses cell receptors(hormones) for recognising other cells
helps cells stick together
What is the function of proteins channels and carrier proteins(2things)
binds molecules or ions and changes its shape to move across the membrane (sometimes uses active transport)
What is the function of the cholesterol(3 things)
adds strength to membrane
prevents loss of water as the molecules are hydrophobic
increases or decreases rigidity depending on the temperature - by making it less fluid
What is the function of the glycoprotein(proteins + carbohydrates)-(3 things)
carbohydrate parts act as a surface receptor for hormones and neurotransmitters
helps attach cells to each other(tissues)
allows lymphocytes(white blood cells)to recognise other cells
What is the function of the glycolipid(3 things)
carbohydrate parts act as a surface receptor for hormones and neurotransmitters
helps attach cells to each other(tissues)
maintains stability of the membrane
name 3 reasons why molecules cant pass the bilayer
not soluble in lipid
too large
charged(hydrophobic tails repel them)
why is the membrane a good barrier
molecules cant pass through bilayer
name 5 ways of moving across a membrane
simple diffusion
facilitated diffusion
omosis
active transport
co-transport
what is simple diffusion and what does it happen through
net movement of particles down the concentration gradient
happens through lipid bilayer(non polar molecules)
name 5 things diffusion if affected by
concentration gradient
surface area to volume ratio
membrane thickness(diffusion distance)
polarity
temperature
