Lab Exam 1 Flashcards
What is the most common microscope in a classroom?
Compound or light microscope
What is the magnification range of a compound/ light microscope? What are the specimens required?
40x-1000x magnification. Thin, 2D specimens required.
What is the magnification of a scanning electron microscope? What kind of images does it produce?
Up to 10,000,000x magnification! Provides surface image of 3D specimens.
What is the magnification of a transmission electron microscope? What images does it provide?
Up to 10,000,000x magnification. 2D image of intracellular structures
What are osmotically active solutes? What is tonicity?
Solutes that cannot pass through the membrane (are “stuck”) will therefore influence the movement of water. These solutes exert an osmotic pressure on water, which pulls water toward them.
What is the difference between molarity and osmolarity?
Molarity is the number of moles of solutes per liter of liquid, whereas osmolarity is the number of osmotically active particles per liter of liquid.
How is molarity calculated, and how do we use dimensional analysis to convert units?
Molarity is moles per liter (mol/L), so we calculate the number of moles with the given gram divided by the substance’s molar mass and then divide it by how many liters of the substance we have. Always cancel units.
•Where are some key ions more concentrated? Inside or outside the cell?
Cl- is more concentrated outside the cell
Ca2+ is more concentrated outside the cell
Na+ is more concentrated outside the cell
K+ is more concentrated inside the cell
What is osmotic equilibrium? What does this movement affect?
Equal solution concentration on either side of the membrane. This movement affects the structure and function of cells.
Define diffusion
The movement of solute from a place of higher to lower concentration. If the solute can move through the membrane (perhaps it is a nonpolar steroid hormone, fatty acid, O2gas, or CO2gas), it will do so by the process of diffusion.
What is osmosis?
The movement of water across a membrane to maintain equal concentration of solutions on either side (osmotic equilibrium). If the solute CANNOT pass through the membrane (perhaps it is a polar carbohydrate or an ion like Na+), but water can, WATER will move by the process of osmosis to establish equal solution concentration of either side of the membrane.
What is the molarity of a solution that contains 10 grams of glucose (C6H12O6) in 1 dL of water?
10g / 1dL x 1 mol/180.00g x 1dL/10^-1L = 0.056M
Canceled units can’t be shown when typed, but always cancel units.
What is molarity?
The measure of concentration that indicates the number of moles of solute added to a solvent (always water for us) to end up with 1 liter of solution (Units: M = moles/L). Molarity is like a recipe for how to mix up a given solution
TRUE OR FALSE: Molarity does not tell you ANYTHING about how many osmotically-active solutes are actually in a solution, BECAUSE sometimes molecules break apart when added to water and sometimes they don’t
True
What is osmolarity?
Osmolarity measures the number of osmotically-active solutes in a solution. It measures solution concentration in terms of the number of osmotically-active solutes in solution. Osmolarity = osmoles of solute/1L of water. Not all solutes are equal when it comes to osmolarity - it depends on whether they dissociate in water or not.
If you put 1 mole of CaCl2 (an ionic molecule) into water, how many osmoles of solutes would you have?
Three osmoles of solutes
What are the common units of osmolarity?
OsM= osmoles/L
mOsM= milliosmoles/L
What is the cell membrane lipid bilayer permeable to?
•Nonpolar (hydrophobic) solutes
•Steroid hormones (testosterone, estrogens, etc.)
•Other lipid molecules (fatty acids, eicosanoids, etc.)
•Non-polar molecules, like gases (O2, CO2, NO, etc.)
•Small polar molecules with no net charge
•Water
What is the cell membrane lipid bilayer impermeable to?
•Polar (hydrophilic) or charged solutes
•Large polar molecules (proteins, carbohydrates, etc.)
•Ions (e.g., Na+, Cl-, K+, Ca2+, H+, HCO3-, etc.)
What is crenation?
When water is pulled out of a cell by osmosis, the cell become shriveled.