Exam 1 (Compiled quiz questions) Flashcards
Compare two blood cells, a macrophage and a lymphocyte. Both are spherical, but the diameter of the macrophage is 18 um and the diameter of the lymphocyte is 9 um. By how many times is the volume of the macrophage larger than the volume of the lymphocyte?
2^3 = 8x
Compare the concentrations of pH 3 and pH 5… how much higher is the pH of 5 than 3?
pH 5 is 100x higher than pH3
Compare concentrations of hydrogen ions at pH3 and pH5.5
pH 5.5 is 300x higher than pH 3
MW = 10 kD, concentration = 10 mg/ml. What is the molar concentration?
10,000 mg/ml = 1 M , 10 mg/ml = 1 Mm
What is the mass of 1 ml of water?
1 g
Suppose you have the same mass per volume concentrations of small molecules X and of large molecules Y. What can you say about their molar concentrations?
Molar concentration of X would be larger than Y
How much energy does a typical adult person consume at rest(in Watts)?
100 W
True/False
When a volume of nitrogen is mixed with a volume of oxygen, their total energy is reduced.
True
Which is true regarding heat?
a) Any form of energy can be turned into heat
b) Heat = temperature
c) Heat cannot be fully converted into other forms of energy
A and C
What are the three forms of dry heat?
Conduction, radiation and convection
“A common misconception is that soap (increases or decreases) the water’s surface tension. Actually, soap does the exact opposite, therefore it (increases or decreases)
A common misconception is that soap INCREASES the water’s surface tension. Actually soap does the exact opposite therefore it DECREASES surface tension appx 1/3
Why does water have a relatively high boiling point?
Molecules are kept together by hydrogen bonds
The smallest size that is clearly visible under an optical microscope is close to ____
250 nm
Which of these molecules should be able to pass through gap junctions:
a) Hexokinase
b) Glucose
c) Potassium ion
d) Influenza virus
B and C
Which of these would form micelles in water?
a) Cholesterol
b) Bile acid
c) Soap
d) Ethanol
B and C
Which of the following is true at a time when a reversible reaction L + R ↔LR reaches equilibrium?
a) Kon = Koff
b) Kon[L][R] = Koff[LR]
c) [L]+[R]=[LR]
B) Kon[L][R] = Koff[LR]
Calcium binds troponin and initiates muscle contraction. Why does removal of free calcium from the cytosol terminate muscle contraction?
Equilibrium between free and troponin-bound calcium shifts towards dissociation
Explain the meaning of turnover number in one sentence
The maximum number of reactions that can be catalyzed by a single enzyme molecule in one second
True/False
Most proteins carry a negative charge because their isoelectric point is lower than physiological pH
True, a protein would be neutral at pH equal to its isoelectric point.
The height of the energy barrier affects…
Reaction rate
Estimate the concentration of H+at pH 2.5
a) 1 mM
b) 3 mM
c) 10 mM
B) 3 mM
Using the formula E = 1.4log(C2/C1) calculate the energy stored in the gradient when the concentration is 105times higher on one side than on the other.
1.4log(10^5) = 1.45 = 7 kcal/mol
If protons were distributed passively, would you expect a higher, lower or equal pH in the cytosol compared to that of the extracellular fluid? Assume that the membrane potential is negative.
Lower pH in the cytosol
(Positive protons would accumulate in the negatively charged cytosol, a higher concentration of protons means a lower pH)
True/False
Both permeant and impermeant solutes contribute to osmolarity
True
Some pain receptors are membrane proteins that pass cations, such as Na+or Ca2+, in response to mechanical pressure. Such proteins can be characterized (using the standard nomenclature) as….
Mechanically gated channels
In what sense is the term “semipermeable membrane” used in physiology?
Permeable for water, impermeable for some chemicals.
How are most large molecules (such as proteins) transported into the cell?
Endocytosis
Many molecules are too large to be handled by membrane transporters. In these cases, whole patches of the plasma membrane become involved in transport. The process is called what?
Endocytosis
Why do we usually disregard hydrogen ions when calculating osmolarity?
They have low free concentration
Osmotic pressure of a 1 M solution of glucose is 25 atm. What does it mean?
If this solution was separated by a semipermeable membrane from pure water, a pressure of 25 atm would have to be applied to the glucose side to prevent water accumulation there.
How do we know that the Na/K pump is electrogenic?
More Na+ is exported than K+ imported.
Calculate the equilibrium potential for a positive monovalent ion, Cin= 0.1uM, Cout= 10 uM
60log(10/0.1) = 60log(100) = 60*2 = 120 mV
If the membrane potential is -30 mV and the equilibrium potential for a positive ion is +30mV, which way would the ion move passively?
Into the cell
How would the membrane potential be affected if permeability for Ca2+ increased?
Depolarization, Positive Ca2+ will move inside and make the cell less negative. This depolarization mechanism operates in the heart muscle
