Cell Transport Flashcards
Parts of cell structures (40 cards)
What is the Phospholipid Bilayer?
We describe the membrane as a “flexible, semi-permeable phospholipid bilayer.” The
membrane is made up of Phospholipid Molecules.
Describe Phospholipid molecules
The “head” is hydrophillic which means it’s attracted to water.
The “tails” are hydrophobic which means they are repelled by water.
Membrane proteins and their functions.
- These proteins in the membrane have a variety of functions that are vital for the survival of organisms.
- Transport proteins and move molecules and ions across the cell membrane.
Transport in cells:
These molecules need to be able to pass through the cell membrane in one of two ways. They are?
- Passive Transport
- Active transport
What is Passive Transport?
Movement down a concentration gradient.
What is Active Transport?
Movement against (up) a concentration gradient.
When we talk about the concentration gradient of a solution we are referring to?
The number of molecules in whatever volume of the solution you are looking at.
A concentration gradient is defined as?
A measure of how the concentration of a solution changes from one place to another.
When something moves “down” or “with” a concentration gradient, it is?
Moving from an area of high concentration to an area of low concentration (this is what is happening during diffusion)
When does passive transport occur? and why?
- When substances are able to enter the cell (across a cell membrane) through processes where NO CELLULAR ENERGY (ATP) IS REQUIRED.
- This is because PARTICLES ARE MOVING DOWN THE CONCENTRATION GRADIENT.
What is simple diffusion?
Diffusion is the spreading out of particles from an area of low concentration to an area of low concentration (i.e down a concentration gradient).
Simple Diffusion and the Cell Membrane.
The structure of the semi-permeable lipid allows small, uncharged molecules and hydrophobic molecules to pass directly through the cell membrane, down their concentration gradient, by simple diffusion.
When does Facilitated Diffusion occur?
Facilitated Diffusion occurs when particles are too big to pass through the plasma membrane on their own from an area of high to low concentration. So they cross the membrane with the help of transport proteins that are embedded in the membrane.
Transport proteins are specific. This means that?
This means that each protein channel only carries one type of molecule.
Facilitated diffusion allows diffusion to occur…
more quickly than simple diffusion.
Unlike simple diffusion, the rate of facilitated diffusion is not affected by the…
“steepness” of the concentration gradient.
Osmosis is a special type of?
Diffusion.
Osmosis is the movement of water…
From an area of high concentration to an area of low concentration (down the concentration gradient of water) across a semi-permeable membrane.
Tonicity is…
A measure of the water potential gradient of two solutions (i.e solutions on either side of the semi-permeable membrane).
Solute is…
The component in a solution that is dissolved into the solvent.
For example, when dissolving salt in water, salt is the solute and water is the solvent.
Water Potential is…
A measure of the tendency of water molecules to move from one place to another.
Solvent definition
The liquid that dissolves the solute.
A Hypertonic solution is…
A solution with the higher concentration of solutes.
A Hypotonic solution is …
A solution with the lower concentration of solutes
