Topic 4 - Cell Physiology Flashcards
(41 cards)
Give the 5 things that make up the Phospholipid bilayer
Cholesterol Extrinsic Proteins Intrinsic Proteins Hydrophobic tails Hydrophilic Heads
Why is the Phospholipid bilayer called the ‘Fluid Mosaic Structure’
The phospholipids in the cell membrane are constantly moving while the proteins are scattered among them
What are Polysaccharides bound either by proteins or lipids to the Cell-Surface membrane called
Glycoproteins and Glycolipids
What are som factors that influence the fluidity of the Cell-surface membrane
The more phospholipids with unsaturated hydrocarbon chains there are, the more fluid is the membrane
Phospholipids with longer hydrocarbon chains decrease the fluidity of the membrane
The membrane is more fluid at high temperatures and less fluid at low temperatures
Cholesterol provides additional binding forces at high temperature, so decreases membrane fluidity, and keeps the membrane in a fluid state at low temperature
What is the function of the Glycocalyx
It allows cells to recognise eachother and group together to form tissues
Why can glycoprotein receptors and signalling molecules fit together
They have complementary shapes
What are the factors that determine the route take across the cell-surface membrane
The size of the molecule
The polarity and non-polarity of the substance
The concentration of the substance either side of the membrane
What is Passive movement across the Cell-surface membrane
It occurs down the concentration gradient and does not require energy expenditure from ATP
What does diffusion rely on
The kinetic energy of the substances in solution
What is the definition of Diffusion
The net movement of a substance from an area of high concentration to an area of low concentration
Why is it called Facilitated Diffusion
The substances movement is facilitated by particular membrane proteins
Give 2 types of membrane proteins
Channel Proteins
Carrier Proteins
What is the structure of Channel proteins
They have a hydrophilic core through which ions and water may diffuse. These channels have a specific shape to allow one type of ions through
How do Channel proteins regulate flow
They open and close their channels
What are aquaporions
The specific water channel,proteins where most water diffuses through
What is the function of carrier proteins
They transport medium-sized molecules such as glucose and amino acids across the cell-surface membrane
How do Carrier proteins work
The molecule binds to a site on the protein, which changes the shape to bring the molecule through the membrane
What is the definition of Osmosis
The movement of water from an area of high concentration to an area of low concentration across a selectively permeable membrane
What is the definition of Osmosis in terms of water potential
The diffusion of water across a selectively permeable membrane from an area of high water potential to an area of lower water potential
What does the addition of solutes to pure water do to the Water potential of the solution
It makes it more negative
What does an increase of Pressure to pure water do to the Water potential of the solution
It makes it more positive
What is the equation for water potential
Water potential = solute potential + pressure potential
What is the Water potential of a cell
The measure of the free energy of the water molecules in a system
Why is the water potential of Pure water always 0
Because all the molecules are free, and there is no solvent to affect the water relations of the cell
