2.1.5 biological membranes Flashcards
what are the components of the fluid mosaic model
phospholipid bilayer made of a hydrophilic phosphate head and hydrophobic fatty acid tails
cholesterol
extrinsic and intrinsic proteins
glycolipids and glycoproteins
what does an extrinsic protein act as
mechanic support
cell receptors
what does an intrinsic protein act as
acts as carrier/channel protein
what does cholesterol do
regulates fluidity of membranes (less fluid at high temps)
prevents leakages
what do glycoproteins and glycolipids do
act as receptors in cell signalling
allow cells to attach to eachother
antigens
explain cell signalling
signal molecules fit to complementary receptor molecules on cell membranes
(drugs can block receptors as they mimic cell signal molecules)
what is diffusion
movement of molecules from high to low concentration across a partially permeable membrane
describe molecules that move by diffusion
small
non-polar
lipid soluble
what is facilitated diffusion
when molecules are too large to use diffusion
describe molecules that move by facilitated diffusion
large = carrier proteins
polar = channel proteins
water soluble
what is osmosis
water moving from high to low water potential through a partially permeable membrane
what is active transport
molecules go from high to low concentration against a concentration gradient through a carrier protein using ATP
what is endocytosis
into the cell via the vesicle
what is exocytosis
out of cell via vesicle
what does hypotonic mean
low concentration outside cell leading to high water potential
what happens to plant cells when the solution is hypotonic
go turgid
what happens to animal cells when the solution is hypotonic
go through cell lysis
what does isotonic mean
same concentration inside and outside
what happens to plant cells when the solution is isotonic
goes flaccid
what happens to animal cells when the solution is isotonic
stays at equilibrium
what does hypertonic mean
high concentration outside cell means low water potential
what happens to plant cells when the solution is hypertonic
gets plasmolysed
what happens to animal cells when the solution is hypertonic
experiences cell crenation (shrivels)
what are the factors affecting fluidity regulation
temperature = higher means more kinetic energy so more fluid
more cholesterol = less fluid
unsaturated fatty acids = more fluid
ethanol dissolves lipids
what are the factors affecting diffusion
higher temperature = higher rate due to more kinetic energy
higher surface area = more molecules can diffuse at once
larger molecules = more resistance
larger concentration gradient = increases rate
larger diffusion pathway = decreases rate
