cell membranes and transport Flashcards
why is it called the FLUID MOSAIC MODEL?
FLUID- VISIONS and INDIVIDUAL PHOSPHOLIPIDS can MOVE position
MOSAIC- embedded with PROTEINS, resulting in a mosaic of components
MODEL- based on SCIENTIFIC EVIDENCE
what do GLYCOPROTEINS act as?
RECEPTORS or ANTIGENS in cell RECOGNITION
what does CHOLESTEROL do?
makes cell more STABLE
what is the function of the phospholipid bilayer?
control the MOVEMENT of substances IN and OUT of the cell. Also to CONTAIN RECEPTORS for other molecules
phosphate heads are…
HYDROPHYLLIC so INTERACT with water. They’re SOLUBLE
fatty acid tails are…
HYDROPHOBIC so REPEL water and are TUCKED into the inner membrane. They’re INSOLUBLE
what factors affect the permeability of the plasma membrane?
HIGH TEMP- increases KINETIC energy meaning phospholipids move more and increases permeability
TOO HIGH TEMP- may DENATURE and DAMAGE membrane
TOO LOW TEMP- ice CRYSTALS may form which PIERCE the cell membrane and increase permeability
ETHANOL and pH
how would the steepness of the concentration gradient affect rates of diffusion?
BIGGER DIFFERENCE in concentration causes a QUICKER rate of diffusion
how does lipid solubility affect rate of diffusion?
NON POLAR molecules diffuse more EASILY than POLAR molecules because they are SOLUBLE in FATTY ACID TAILS
how does surface area affect rate of diffusion?
The GREATER the surface area the FASTER the diffusion can take place. This is because the MORE MOLECULES/IONS can cross the membrane at any one moment.
name 4 factors that affect the rate of diffusion
TEMPERTURE, LIPID SOLUBILITY, STEEPNESS OF CONC GRADIENT and SURFACE AREA
what is facilitated diffusion?
- requires a CHANNEL PROTEIN in the cell membrane to transport LARGE, POLAR molecules, charged and water soluble molecules across the membrane.
what is simple diffusion?
- the passive movement of SMALL, NON POLAR lipid soluble molecules such as co2 from an area of HIGH concentration to an area of LOW concentration.
- molecules move directly THROUGH the phospholipid BILAYER
what is active transport?
- can transport ALL TYPES of molecules through CARRIER PROTEINS from an area of LOW concentration to an area of HIGH concentration.
- requires ENERGY in the form of ATP.
what is cytosis?
a form of active transport where parts of the plasma membrane form INFOLDINGS/OUTFOLDINGS There are two types of cytosis - EXOCYTOSIS + ENDOCYTOSIS
