Biochemistry 3304 Practice Exam 1

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Questions and Answers

Which of the following would not have significant overlap with Biochemistry?

Cell Biology

Medicinal Chemistry

Immunology

None of the above because all overlap with Biochemistry. (correct)

How can functional groups enable interactions between biological molecules?

Complementarity of charge

Complementarity of reactivity

Complementarity of structure

All of the above can be important. (correct)

What is the following functional group represented as O R H?

Carboxylic acid

Thiol

Aldehyde (correct)

Alcohol

What is the following functional group represented as O R2 R1 N H?

Amide Signup and view all the answers

Which amino acids exhibit protonation/deprotonation states that are significant at physiological pH?

H, C Signup and view all the answers

What is the following functional group represented as R SH?

Thiol Signup and view all the answers

What is the approximate pI for the peptide MEKVDRP given the following pKa values?

6.5 Signup and view all the answers

Compartmentation conferred what kind of advantage for early cellular organisms?

Concentrated the molecules and reactants necessary for important biological processes. Signup and view all the answers

What is the underlying theory behind evolutionary processes?

All the choices are correct. Signup and view all the answers

Which of the following pKa values corresponds to the carboxyl terminus of a peptide?

3.5 Signup and view all the answers

The Second Law of Thermodynamics defines what thermodynamic principle?

Entropy Signup and view all the answers

Which amino acid has the highest pKa value listed?

Arginine Signup and view all the answers

What is the pKa value for Lysine's side chain?

10.5 Signup and view all the answers

How do proteins typically achieve their globular structure in an aqueous environment?

By maximizing interactions among non-polar sidechains Signup and view all the answers

What is the primary process responsible for the movement of water during the initial phase of dialysis?

Osmosis of water molecules into the dialysis bag Signup and view all the answers

Which statement correctly describes the outcome of clustering non-polar molecules in an aqueous environment?

It minimizes the exposure of non-polar molecules to water. Signup and view all the answers

What is the correct interpretation of a solution of formic acid that is 10% ionized at a pH of 2.7?

The ratio of HCOO- to HCOOH is 1 to 9. Signup and view all the answers

What is the pH of a solution with a concentration of 0.0001M NaOH?

10 Signup and view all the answers

How would you describe dialysis in the context of solute movement?

It involves the movement of soluble molecules across a semipermeable membrane. Signup and view all the answers

What is the pKa of a solution of formic acid at a pH of 2.7 if it is 10% ionized?

3.75 Signup and view all the answers

What is a consequence of the exclusion of water from the hydrophobic interior of the protein?

It releases water molecules into the bulk surroundings. Signup and view all the answers

What is the Gibbs free energy change (∆G) for the reaction given that ∆Go is 2.5 kJ/mol and the concentrations of A and B are 2 mM and 4 mM, respectively?

4,217 J/mol Signup and view all the answers

At what temperature does the reaction described become non-spontaneous?

186 K Signup and view all the answers

What is the entropy change (∆S) for the reaction if ∆G is 8.7 kJ/mol and ∆H is -15.2 kJ/mol at standard temperature?

-81.6 J/mol K Signup and view all the answers

What is the equilibrium constant (Keq) for the reaction where the concentrations of A and B are 10 mM and 1 mM, respectively?

0.1 Signup and view all the answers

If the standard Gibbs free energy change (∆Go) for a reaction is 2.5 kJ/mol, what can be inferred about the direction of the reaction at standard conditions?

A Signup and view all the answers

How is the Gibbs free energy change (∆G) related to the concentrations of reactants and products?

It is affected by the ratio of products to reactants. Signup and view all the answers

What is the numerical value of ∆Go for the reaction if the Gibbs free energy change is positive?

2.5 kJ/mol Signup and view all the answers

If the equilibrium constant (Keq) for a reaction is 0.36, what can be inferred about the concentrations of A and B?

Concentration of B is greater than A. Signup and view all the answers

How many milliliters of 1M NaOH are needed to increase the pH from 5.09 to 7.09?

80 ml Signup and view all the answers

At pH = 5.35, what is the relative quantity of H2CO3 compared to HCO3- and CO32-?

90 H2CO3, 10 HCO3-, and negligible CO32- Signup and view all the answers

What is the approximate pKa for an acid represented by a titration curve that levels off at 10?

10 Signup and view all the answers

Which amino acid sidechains could be represented by a titration curve exhibiting two distinct transitions?

Cysteine and Tyrosine Signup and view all the answers

Which of the following amino acids can undergo post-translational modification by a kinase on an alcohol sidechain?

Ser, Thr, Tyr Signup and view all the answers

Identify the amino acids corresponding to the letters V, H, S, K.

V, H, S, K Signup and view all the answers

Which pKa value indicates a strong relationship with a basic amino acid at physiological pH?

10.33 Signup and view all the answers

To achieve a high deprotonation percentage of MES at pH 7.09, what is the necessary change in percentage from pH 5.09?

80% Signup and view all the answers

Study Notes

Biochemistry Exam Review

Biochemistry overlaps with various scientific disciplines, including Cell Biology, Medicinal Chemistry, and Immunology. All listed areas have significant overlap with Biochemistry.
Functional groups in biological molecules enable interactions through:
- Complementarity of charge
- Complementarity of reactivity
- Complementarity of structure
Common functional groups include:
- Carboxylic acid represented as R–C(=O)–OH
- Aldehyde is represented as R–C(=O)–H
- Amide structure is R1–C(=O)–N–H
- Thiol characterized by R–SH
- Phosphate diester represented as R–O–P(=O)–O–R
Compartmentation in early cellular organisms concentrated essential molecules, aiding biological processes and separating internal cellular environments.
Evolutionary processes are not goal-directed; they involve:
- Random variation, continual change, and survival of organisms with beneficial traits.
The First Law of Thermodynamics relates to the conservation of energy while the Second Law defines the principles of entropy.
Observations on a first aid heat pack show that an exothermic reaction becomes hot and results in decreased entropy.
To reverse an exothermic reaction, increasing temperature is most effective.
For a unimolecular reaction A → B with concentrations of 10 mM and 1 mM respectively, calculated ∆G° is +5.7 kJ/mol.
Given ∆G° and enthalpy of a reaction, the entropy can be calculated; example provides entropy as approximately 81.6 J/mol·K at standard temperature.
Non-spontaneity of reactions is determined by the temperature where ∆G = 0; for specific reactions, this occurs at 186 K based on provided values.
Adjusting concentrations in reactions leads to equilibrium shifts; example solution provides a scenario showing that A < B.
Calculating ∆H° for reactions requires thermodynamic data from multiple temperatures and equilibrium constants.
The hydrophobic effect influences protein structure by promoting globular arrangements favoring non-polar interactions in aqueous environments.
Dialysis is defined as the movement of soluble molecules across semipermeable membranes from higher to lower concentration regions which can also involve water movement through osmosis.
The pH of a 0.0001M NaOH solution is 10, calculated using the inverse logarithm of H+ ion concentration.
Formic acid, when 10% ionized at pH 2.7, gives a calculated pKa of approximately 3.75 using the Henderson-Hasselbalch equation.
To change pH from 5.09 to 7.09 in a MES buffer, approximately 80 millimoles of 1M NaOH are required (or 80 ml).
For a diprotic acid like H2CO3 with two pKa values, pH 5.35 indicates predominantly H2CO3 with negligible amounts of CO32-.
Titration curves can help determine pKa values; near the midpoint of a curve generally denoting pKa.
Amino acids that undergo phosphorylation via kinases include Serine, Threonine, and Tyrosine.
Amino acids exhibit varying protonation states at physiological pH, particularly His, Cys, and other polar and charged side chains.
Isoelectric point (pI) calculations involve evaluating the pKa values around the neutral charge of a peptide. Calculated pI for MEKVDRP with given pKa values approximates to 6.5.

This review covers critical aspects of Biochemistry relevant for examination preparation, focusing on structural, functional, thermodynamic, and evolutionary concepts.

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Test your knowledge of biochemistry concepts with this practice exam for Biochemistry 3304. Explore topics such as the overlap of biochemistry with other scientific fields and the role of functional groups in biological interactions.