MODULE 1: CELL AND MOLECULAR BIOLOGY Flashcards
What happens when phospholipids are surrounded by water? And what is this arrangement called?
They spontaneously arrange themselves in two layers with their hydrophilic heads extended outwards into the water, and their hydrophobic tails inwards away from the water. This is a phospholipid bilayer.
Why is it important to have a phospholipid bilayer?
To regulate what enters and exits the cell because the conditions for metabolic processes must be maintained. Cell integrity must be protected as well as coordination with the other cells within the body must be managed.
What is the difference between plant and animal lipid bilayers?
Plant bilayers contain a lipid called stigma-sterol while animal lipid bilayers have cholesterol.
What are the two types of proteins found in the phospholipid bilayer?
Integral (intrinsic) and Peripheral (extrinsic)
What do integral proteins consist of?
Transmembrane proteins, glycoproteins and glycolipids.
What are transmembrane proteins?
Trans membrane proteins are proteins that are that span the width of the bilayer and protrude on either side.
Describe glycoproteins and glycolipids.
Glycoproteins are a type of transmembrane protein with short chains of carbohydrates attached on the surface of the plasma membrane. They aid with: Hormone recognition, cell signalling and warding off pathogens. Glycolipids are a type of transmembrane protein that have a short chain of lipids and attach to the surface of the plasma membrane. They aid with: Antibody recognition.
What are peripheral proteins?
These proteins do not extend into the hydrophobic region of the bilayer and attach to portions of transmembrane proteins.
How may proteins become specialized?
Some transmembrane proteins float freely while some are anchored to the cytoskeleton. This results in the segregation of proteins leading to functional specialization of different regions of the cell surface. For example the synapses between motor neurones and muscle cells.
Describe water potential.
Water potential is the stored energy water possesses due to its position.
What is water potential affected by?
The concentration of dissolved particles or solutes in a solution.
What is hydrostatic pressure?
This is the unit of measurement of water potential and is the pressure required to stop the movement of water under particular conditions. Measure in megapascals (MPa) or bars.
What is bulk flow?
The process by which water and solutes all move together from one part of a multicellular organism to another part. Example: Blood flow
What is diffusion?
Diffusion is the movement of particles from an area of high concentration to an area of low concentration down a concentration gradient.
What is osmosis?
Osmosis is a special type of diffusion that refers to the movement of water particles from an area of high conc. to and area of low conc. through a selectively permeable membrane.
