Test 1 Flashcards
What makes carbon such an abundant element in biomolecules?
it forms stable covalent bonds by electron pair sharing
Which of the following is true for the polymerization reactions that produce proteins, polysaccharides and nucleic acids.
They involve bond formation by the elemination of water
Which of the following is a true statement about non-covalent bonds?
Hydrogen bonds, ionic bond and hydrophobic interactions
all carry a degree of
specificity while van der Waals interactions are induced.
Which of the following is the correct order of the molecular organization in the cellular hierarchy?
water, pyruvate, amino acids, proteins, ribosomes
When the relative strengths of non-covalent bonds are
determined by the size of the
atoms as well as the distance between them, this describes:
Van der Waals interactions
All of the statements about structural complementarity are true EXCEPT.
produces strong irreversible interactions.
Rank the following bonds in order of increasing bond strength.
Van der Waals, electrostatic, hydrogen bond, covalent single bond
Membrane structures are maintained primarily by:
hydrophobic interactions.
Which of the following characteristics is specific for prokaryotic cells, but NOT eukaryotic cells?
Prokaryotic cells lack a cytoskeleton.
What ionic forms of phosphoric acid are present at pH 7.0.
The pKas of phosphoric acid are 2.1, 7.2, and 12.4.
H2PO4^- and HPO4^-2
Addition of ethanol to a solution of magnesium chloride would result in all the following except
A decrease in the electrostatic force between the Mg 2+ and the Cl-ions
When nonpolar molecules are dissolve in water, which of the following is true
the nonpolar molecule produces a reorganization of water surrounding the molecule, effectively decreasing the hydrogen bonding network in water
Addition of glucose to water results in all of the following effects EXCEPT.
The lowering of the boiling point of the solution.
Which of the following is true about buffer systems?
They will have an area on their titration curve where the greatest buffering capacity exists
Intracellular pH is maintained primarily by the ________ and __________ buffer systems, and the extracellular pH by the ____________ buffer system.
HPO42-/ H2PO4-, histidine, HCO3-/ H2CO3
Which statment is incorrect about macromolecules?
Carbohydate polymers are compsed of monosaccarides linked by ester bonds
All of the following activities require the presence of ATP or NADPH EXCEPT.
none, they are all energy-requiring activities
All will cause the denaturation of a protein EXCEPT.
Refrigeration.
All of the following characteristics are associated with the solvent water EXCEPT:
low heat capacity.
Thermodynamics does NOT:
provide information on the rate of a reaction.
Living systems are:
open systems exchanging both energy and matter with their surroundings.
An example of an open system would be:
a gas burner/ a pot of boiling water
Which example has the greatest increase in entropy, Triangle S?
sublimation of CO2
Calorimeter measures ______________ by a biochemical process.
heat absorbed or given off
The second law of thermodynamics states that:
Naturally occurring processes proceed to a state of minimum potential energy
The enthalpy of a system may not change from state 1 to 2 by a change in
entropy
When are enthalpy internal energy equivalent?
When there is no PV work accomplished
If △G for a reaction is negative, then
△ S can be either negative or positive
Which of the following sentence about spontaneity is correct?
A reaction with a negative △G will be spontaneous
The reaction A+B→C+D is to be at equilibrium when
Its energy charge △G is zero
What is the energy change of a solution when a salt, such as MgCl2, is dissolved in water?
Decrease
An important characteristic of living system is that they
Are never at equilibrium
Which of the following processes has a negative change in entropy?
the hydration of Na+ion
The subunits of many oligomeric proteins associate as the temperature is increase from 4 °C to room temperature. Which of the following is best explanation for this effect?
The term –T ΔS becomes more negative at higher temperatures making the ΔG of association more negative
ATP exhibits which of the following characteristics
It is a thermodynamically stable molecule
Consider the following reaction which has a △G of +0.64 kj/mol succinate + Q <——>fumarate + QH2. These four compounds are mixed at 0.01M each and allowed to equilibrium. Which statement is correct about the resulting concentration of Q at equilibrium?
[QH2] < [Q]
Thermodynamic parameters (entropy, enthalpy, free energy, and internal energy) are given for an unknown enzyme. Explain which results would be expected for the breaking of hydrogen bonds and the exposure of hydrophobic groups from the interior during the unfolding process of a process of a protein.
enthalpy change, △H, is positive
All of the statements below about metabolism are true except:
Metabolism occurs in the mitochondria of prokaryotes
Which of the following statements about water is false:
Pure liquid water consist of H2O molecule in a highly ordered three dimensional network of hydrogen bonds
For a weak acid solution pH=pKa when
[A-]=[HA]
Buffers have all of the following characteristics except they:
Buffer best for polyprotic acids halfway between the two pKa values
An example of a system at equilibrium would be:
death of a fucking living system fuck this shit
Which of the following cannot function as a hydrogen bond donor to water at pH 3.0?
Acetylaldehyde
Which of the following weak acid would makes the beat buffer at pH = 5.0?
Acetic acid (ka= 1,7 x 10^-5
