Mr P- bio 6 cell membranes Flashcards
(31 cards)
What are the charges on the different groups within a phospholipid?
Phosphate group has a negative charge (polar) and fatty acids don’t have a charge (non-polar)
Which part of the phospholipid is hydrophilic and which part is hydrophobic?
Phospho-glycerol head= hydrophilic
Fatty acid tails= hydrophobic
What is the structure of the plasma membrane described as?
Fluid mosaic
Why is a cell membrane described as a fluid mosaic?
FLUID= the phospholipids are constantly movi mg about giving a fluid structure
MOSAIC= protein molecules are unevenly distributed throughout the membrane, forming a mosaic
What try or if substances does a phospholipid bilateral act as a barrier to?
Polar molecules and ions
Why is the phospholipid bilayer acting as a barrier to most water soluble substances useful?
Ensures water- soluble molecules such as sugars, amino acids and proteins cannot leak out of cell and unwanted water-soluble molecules cannot get in
What does a phospholipid bilayer allow to pass through?
Small non charged (Lipid- soluble molecules)
What do ions and polar molecules pass through?
Channel proteins
What two processes do carrier proteins carry out?
Facilitated diffusion and active tranpsort
What does cholesterol do?
Regulates the fluidity of the membrane
Other than carrier and channel proteins, what can other proteins be within the membrane?
Specific receptors for hormones
What are the ‘channel proteins’ that allow water in called?
Aquaporins
What are the two types of receptors?
Glycolipids and glycoproteins
What do glycolipids and glycoproteins contain allowing them to act as receptor molecules?
Carbohydrate chains
What are the 3 main receptor types?
Signalling receptors (hormones and neurotransmitters), receptors involves in endocytosis and receptors involved in cell adhesion and stabilisation
What are the 4 types of movement of substances ina do out of the cell?
Diffusion, facilitated diffusion, osmosis and active transport
What is facilitated diffusion?
A hydrophilic substance can’t pass through hydrophobic phospholipid bilayer so instead move through he membrane via channel or carrier proteins
What do channel proteins allow to diffuse through the cell membrane?
Charged substances (e.g. ions)
What does the direction of movement of molecules through the carrier proteins depend on?
The relative concentration on each side of the membrane
Is facilitated diffusion a passive or active process and how long does it occur for?
Passive and until it reaches equilibrium
Is movement using a carrier protein passive or active process?
Active (active transport)
Why is movement through a carrier protein active tranpsort?
Moves against the conc gradient
What is the water potential?
Pressure of water on the membrane
What is the water potential of water?
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