Flashcards in Transport Across the Membrane Deck (32)
Means fearing water
e.g the fatty acid tails in the cell membrane are non-polar
-Means water loving
e.g the phosphate heads are hydrophobic in the cell membrane
Define Active Transport
The movement of molecules from a region of low concentration to a region of high concentration, requiring the energy in the form of ATP.
Define the Fluid Mosaic Model
A phospholipid bi-layer studded with large proteins.
Explain a glycoproteins role
Cellular recognition (self or non-self) and signalling molecules
Explain a glycolipids role
They are receptors and markers and are essentially carbohydrate rings bonded to a lipid.
Impact of a hypertonic solution on a cell.
Loose water, animal cells will become shrivelled and plant cells will undergo plasmolysis
Impact of hypotonic solution on a cell
Gain water, animal cells will expand and can lyse (burst). Plant cells expand however the cell wall prevents it from rupturing.
Impact of an isotonic solution on a cell
No net movement, doesn't gain or loose water
Define a hypertonic solution
Has a higher solute concentration than the solution it is compared with. (Cell will loose water)
Define a hypotonic solution
Has a lower solute concentration than the solution it is being compared with (Cell will gain water)
Define an Isotonic solution
Has the same solute concentration as the solution being compared with.
Examples of molecules that can pass through a membrane via simple diffusion.
Alcohol and steroids (non-polar)
H2O, gases, urea, (small polar)
Explain the Fluid Mosaic Model
Cell membranes consist of a bi-layer of phospholipids with embedded proteins floating throughout.
The passive net movement of water molecules from a region of low solute concentration to a region of high solute concentration, through a semi-permeable membrane.
Define a Simple Diffusion
The passive net movement of molecules across a semi-permeable membrane from areas of high concentration to areas of low concentration.
Define Facilitated Diffusion
The passive net movement of molecules across a semi-permeable membrane, via protein channels or protein carriers. The molecules, are moving from areas of high concentration to areas of low concentration.
The solute is dissolved into the solvent
e.g the salt in the saline solution
The substance that the solute gets dissolved into
e.g the water in the saline solution
A mixture in which the solute evenly distributed throughout the solvent
Explain carrier proteins
Upon binding with a SPECIFIC molecule, carrier proteins create an opening in the lipid bi-layer by undergoing a conformational change, thus enabling the larger and more polar molecules to exit.
Define Bulk Transport
Vesicle mediated active transport that involves the movement of large particles across the cell membrane.
What type of substances use facilitated diffusion.
They are too large
What are the factors affecting permeability
Temperature, state of substance, surface area and composition of a membrane.
Define Simple Diffusion
The passive net movement of molecules across a semi-permeable membrane from areas high concentration to areas of low concentration.
Why is the properties of the phospholipid bi-layer important to the structure of the membrane.
- Sufficient flexibility to form vesicles around particles to be transported
-Ability to move laterally to allow the folding of the membrane
-Allows passage of lipid-soluble molecules.
-Makes the membrane strong and hard to break.
What are the three key aspects of the cell theory
-All living organisms are comprised of cells
-Cells are the basic unit function of life
-All new cells arise from pre-exsisting cells
What are some distinct features of prokaryotic cells
No membrane bound organelles
No membrane bound nucleus
Distinct features of a eukaryotic cell
Distinct membrane bound nucleus
membrane bound organelles
What is the role of the cell membrane?
To control movement of molecules in and out of the cell
What does the cell membrane consist of
A phospholipid bilayer studded with proteins