Vocab
Molecules move from a concentrated area to another of lesser concentration by Brownian motion.
Passive transport/diffusion
Explain passive transport
molecules move from areas of high to low concentration down/with a concentration gradient. Does not require energy.
What is the MOST HYPOTONIC solution discussed in class?
Distilled water, it is 100% H2O molecules.
Explain how the cell membrane is a selectively permeable barrier.
The cell membrane allows some molecules to pass through the phospholipid bilayer, but not all molecules are small and nonpolar enough to do so. Certain proteins in the membrane allow specific molecules through at certain times.
Can ions move across the phospholipid bilayer by SIMPLE diffusion? Why or why not?
No they are too charged, have to cross through FACILITATED diffusion
Cells placed in this solution would would already be at dynamic equilibrium.
Isotonic
What are the 3 examples of passive transport?
Simple diffusion, osmosis, facilitated diffusion.
What two structures does water pass through during osmosis?
Phospholipid bilayer and the aquaporins in the cell membrane.
List 5 of the major components of the cell membrane
Phospholipid bilayer, glycolipids, glycoproteins, peripheral proteins, aquaporins, Transmembrane protein channels, protein pumps, cholesterol, hydrophobic center, hydrophilic phosphate heads of phospholipids.
Explain how molecules move in relation to their concentration gradients across a membrane during ACTIVE transport.
They move up/against their concentration gradient from areas of low to high concentration.
Examples of molecules that would use exocytosis and endocytosis to leave their producing cells and enter their target cells.
Enzymes, hormones
How does facilitated diffusion use proteins without using energy?
The proteins act as a bridge or a wider “doorway” through the cell membrane to allow large molecules to diffuse across the membrane with their concentration gradient without using energy.
If a cell with a WATER concentration of 99% is placed in solution with a SOLUTE concentration of 85%, where will water in the system move via osmosis?
Out of the cell
Why does the structure of the phospholipid bilayer prevent the SIMPLE diffusion of charged molecules? How do the ions work around this issue?
The hydrophobic center will not allow them through so the ions travel across the membrane via transmembrane proteins.
What energy molecule is consumed to make active transport of molecules possible? Where in that molecule does the energy come from?
ATP- energy in the bond between the second and third phosphate group.
When a cell has been submerged in a hypotonic solution and explodes due to the movement of water by osmosis
Cytolysis
Would molecules such as O2 and CO2 be able to diffuse through a membrane? Why or why not?
Yes, they would because they are small molecules and uncharged/nonpolar.
A cat cell has an internal concentration of 10% solute. What would happen to the cat's cells if they was given an IV fluid of 12% solute concentration? What is the tonicity of the CELL compared to the IV fluid?
The CELL is hypotonic, Water would leave the cell.
How are the phospholipids oriented the way they are? Why are they arranged this way?
Their hydrophilic heads face the extracellular and intracellular space, while the hydrophobic tails face inwards toward one another. This is because the molecules want to be near other molecules of similar polarity.
How many sodium ions are moved out of the cell by the Na+/K+ pump? What direction are they moving?
Na+ 3 ions moved out of the cell at a time.
When a cell has been submerged in a hypertonic solution and shrivels due to the movement of water by osmosis.
Plasmolysis
What is the goal of diffusion/passive transport?
To achieve dynamic equilibrium within a system.
What is turgor pressure? Why would you want your vegetables to have cells with a high turgor pressure?
Turgor pressure is the pressure inside a plant cell due to water. Vegetables with higher turgor pressure are more crunchy and fresh.
What is the function of an aquaporin?
To allow water to diffuse across the membrane, avoiding the hydrophobic space within the two monolayers.
We watched a video in class of a neutrophil in the human body attacking and engulfing a bacterial cell, this is an example of what type of active transport?
Endocytosis, specifically phagocytosis.