How do we fuel our body? Flashcards
What is the Plasma Membrane?
- Boundary of cell – encloses and supports cell contents.
- Separates intracellular vs. extracellular materials.
What is the Fluid Mosaic Model?
-Attaches cells to other cells and to the surrounding matrix.
-Cells communicate with their environment through their cell membrane.
-Determines what can move into and out of the cell (selectively permeable).
o Intra- and extracellular environment is different
-Difference in charge across membrane – membrane potential
-Structure – fluid mosaic model
What is the lipid bilayer made of?
- Phospholipids
- Cholesterol
What are proteins in the Fluid Mosaic Model?
- Inserted in the lipid bilayer
- Peripheral or integral
- Many are involved in transporting molecules across the cell membrane, e.g. channel proteins, carrier proteins, ATP powered pumps.
What are channel proteins?
-Form a tiny channel through the plasma membrane
-Molecules of certain size, shape and charge can pass through
-Non-gated ion channels
oAlways open
-Gated ion channels
oOpened or closed by certain stimuli
What are carrier proteins?
-Also called transporters
-Integral proteins move ions from one side of membrane to the other
o Specific binding sites
o Protein changes shape to transport ions or molecules
o Resumes original shape after transport
o Uniporters, symporters, antiporters
What is ATP-Powered transport?
- Requires energy in the form of ATP.
- Transports substances AGAINST their concentration gradient, so the cell can accumulate substances.
- Example we learn is the sodium potassium pump.
What is a Solute?
- Dissolved substance in a solution
- e.g. glucose, sucrose, ions (Na+, K+, Cl-)
What is Solvent?
- Liquid that holds solutes
- Generally, water
What is Solution?
-Mixture formed when solute dissolved in solvent
What is Diffusion?
- Molecules move from an area of higher concentration to an area of lower concentration.
- Continues until the molecules have evenly distributed themselves throughout the solution.
What is Diffusion through the cell membrane?
- Certain specific nonlipid soluble molecules or irons diffuse through membrane channels
- Other non-lipid soluble molecules, for which membrane channels are not present, can’t enter the cell
- Lipid soluble molecules diffuse directly though the plasma membrane
What is Filtered Diffusion?
- Move large, water soluble molecules or electrically charged molecules across the plasma membrane.
- Amino acids and glucose in, manufactured proteins out
- Passive
What is Osmosis?
-Osmosis is the diffusion of water across a selectively permeable membrane, e.g. the plasma membrane
What
- A selectively permeable membrane lets water to pass through, but any solutes dissolved in the water
- If the beaker contains distilled water (water with no solutes), water molecules will move back and forth across the membrane at the same rate
- The water level stays the same on both sides of the membrane