51 Questions
What is the primary reason why water serves as the universal intracellular and extracellular medium?
Its ability to form hydrogen bonds and its polar character
What is the term used to describe substances that can readily dissolve in water?
Hydrophilic
What is the main reason why ionic compounds like NaCl can dissolve in water?
The formation of hydration shells and the high dielectric constant of water
What is the term used to describe the shells of water molecules that surround ions in solution?
Hydration shells
What is the result of the interaction between the negative ends of the water dipoles and cations, and the positive ends and anions?
The hydration of ions
Why do nonpolar substances like hydrocarbons show only limited solubility in water?
Because they cannot form hydrogen bonds
What is the outcome of the energy released in the interaction between ions and dipolar water molecules?
The overcoming of charge-charge interactions stabilizing the crystal
What is the timeframe represented by successive frames in the schematic 'motion picture'?
Picoseconds
Which of the following macromolecules is responsible for storing and transcribing genetic information?
Nucleic acids
What is the main function of lipids in biological systems?
Energy storage and membranes
Which of the following is NOT a characteristic of prokaryotic cells?
They have a true nucleus
What is the role of pili in prokaryotic cells?
They aid in attaching the organism to other cells or surfaces
What is the location of the DNA in prokaryotic cells?
In the form of one or more molecules that exist free in the cytosol
Which of the following is an example of a biological function of proteins?
All of the above
What is the term for the process of forming macromolecules through condensation reactions of monomers?
Polymerization
What is the field of study that seeks to understand heredity and the expression of genetic information in molecular terms?
Molecular genetics
What is the primary function of the dihydrogen phosphate–hydrogen phosphate system in cells?
To control intracellular pH
Which system provides significant buffering capacity in blood?
The carbonic acid–bicarbonate system
What is the definition of a system in bioenergetics?
Any part of the universe that we choose for study
Which of the following is an example of a closed system?
A sealed bottle of soda
What is the primary difference between an open system and a closed system?
The ability to exchange matter
Should a human be considered an open, closed, or isolated system?
An open system
What is the definition of internal energy (U) in a system?
The total energy of a system that can be exchanged through simple physical processes or chemical reactions
What is the characteristic of an isolated system?
It can exchange neither energy nor matter
What is the direction of a thermodynamically favored process?
In the direction that minimizes free energy
Which of the following is a characteristic of exergonic processes?
Negative free energy change
What is the role of a catalyst in a thermodynamically favored process?
It increases the rate of the reaction
What is the significance of the entropy of an open system?
It can decrease in certain cases
What is the equation that describes the folding of proteins?
ΔG = ΔH - TΔS
What is the significance of the free energy change, ΔG?
It is a measure of the maximum useful work obtainable from a reaction
What is the consequence of life involving a temporary decrease in entropy?
Energy is expended
What is the role of enzymes in biological systems?
They selectively increase the rate of specific thermodynamically favorable reactions
What is the characteristic of 'high-energy' phosphate compounds?
They have very large negative free energies of hydrolysis
What is the result of the release of the orthophosphate ion in a hydrolysis reaction?
An entropy increase in the system
What is the abbreviation for inorganic phosphate?
Pi
Why is resonance stabilization important in phosphate hydrolysis reactions?
It applies to all phosphate hydrolysis reactions
What is the characteristic of the hydrolysis reactions of biochemically important phosphate compounds?
They have very large negative free energies of hydrolysis
What is the role of orthophosphate ion in biological systems?
It is a byproduct of hydrolysis reactions
Why are phosphate hydrolysis reactions favored in biological systems?
They lead to an increase in entropy
What is the significance of ATP molecule in biological systems?
It is a source of energy
What is the branch of science that seeks to describe the structure, organization, and functions of living matter in molecular terms?
Biochemistry
Biochemistry can be divided into how many principal areas?
Three
Proteins, polysaccharides, nucleic acids, and lipids are examples of macromolecules.
True
___________ are formed by condensation reactions of the monomers.
Polymers
What is the basic unit of biological organization?
The cell
Match the following macromolecules with their biological functions:
Polysaccharides = Structure, energy storage Nucleic acids = Storage and transcription of genetic information Proteins = Structure, enzymes, hormones, receptors Lipids = Energy storage, membranes
What is the equation that expresses the first law of thermodynamics?
ΔU = q - w
What is enthalpy defined as?
H = U + PV
What does the Gibbs free energy include?
Both energy and entropy
Processes with a negative free energy change are endergonic.
False
In biological systems, what type of reactions drive countless reactions by coupling with them?
Exergonic reactions
Study Notes
Genetic Biochemistry
- Genetic biochemistry is the chemistry of processes and substances that store and transmit biological information
- It's also the province of molecular genetics, which seeks to understand heredity and the expression of genetic information in molecular terms
Macromolecules
- Many macromolecules are polymers, formed by condensation reactions of monomers
- Examples of macromolecules:
- Proteins
- Polysaccharides
- Nucleic acids
- Lipids
Biological Functions of Macromolecules
- Polysaccharides: structure, energy storage
- Nucleic acids: storage and transcription of genetic information
- Proteins: structure, enzymes, hormones, receptors
- Lipids: energy storage, membranes
Biochemistry as a Biological Science
- The cell is the basic unit of biological organization
- Cell types:
- Prokaryotes (always unicellular, including true bacteria and archaea)
- Eukaryotes (may be unicellular or multicellular)
Cell Structure
- Prokaryotic cell structure:
- Plasma membrane and cell wall
- Cytoplasm with cytosol, DNA, and ribosomes
- Cell surface may have pili and flagellae
The Role of Water in Biological Processes
- Water serves as the universal intracellular and extracellular medium due to its:
- Ability to form hydrogen bonds
- Polar character
- Hydrophilic substances can readily dissolve in water
- Water is an excellent solvent for ionic compounds due to:
- Hydration shells
- High dielectric constant
Energy, Heat, and Work
- Bioenergetics: the study of how organisms capture, transform, store, and utilize energy
- Systems:
- Isolated: exchanges neither energy nor matter
- Closed: exchanges energy but not matter
- Open: exchanges both energy and matter
- Human and organisms are considered open systems
- Internal energy (U) includes all forms of energy that can be exchanged via physical or chemical processes
Free Energy: The Second Law in Open Systems
- Free energy (ΔG) determines the favorability of a process
- ΔG = ΔH - TΔS
- Processes with -ΔG are exergonic (favorable), while those with +ΔG are endergonic (unfavorable)
- Enzymes increase reaction rates but do not change the favored direction
- The entropy of an open system can decrease
High Energy Phosphate Compounds
- These compounds have very large negative free energies of hydrolysis
- Examples:
- ATP
- Phosphocreatine
- Phosphoenolpyruvate
- Hydrolysis reactions release orthophosphate (Pi), which increases entropy and is therefore favored
- Resonance stabilization applies to all phosphate hydrolysis reactions
Biochemistry: Course Overview
- Attendance in laboratories and seminars is mandatory, with only one allowed absence without excuse and one allowed lateness per semester
- Late arrivals are considered absences, with a 5-point deduction for every subsequent lateness
- Students must submit a doctor's excuse for absences within 7 days to the course coordinator
Assessment Structure
- Total of 200 points
- Exam (final): 100 points
- Midterms (winter and summer): 25 points each
- Seminars and labs: 10 points each (winter and summer)
- Lectures: 5 points each (winter and summer)
Literature
- Required textbooks: Harpers Illustrated Biochemistry (at least 29th Edition), Lubert Stryer's Biochemistry (at least 4th Edition), and Biochemistry: Concepts and Connections
- Recommended texts: None listed
What is Biochemistry?
- Biochemistry is the study of the structure, organization, and functions of living matter in molecular terms
- Three principal areas of biochemistry:
- Structural chemistry of living matter's components and their relationships to biological function
- Metabolism: the totality of chemical reactions that occur in living matter
- Genetic biochemistry: the chemistry of biological information storage and transmission
Biochemistry as a Chemical Science
- Macromolecules: proteins, polysaccharides, nucleic acids, and lipids
- Many macromolecules are polymers formed by condensation reactions of monomers
- Biological functions of macromolecules:
- Polysaccharides: structure, energy storage
- Nucleic acids: storage and transcription of genetic information
- Proteins: structure, enzymes, hormones, receptors
- Lipids: energy storage, membranes
Biochemistry as a Biological Science
- The cell is the basic unit of biological organization
- Prokaryotes (e.g. bacteria, archaea) are unicellular, with a plasma membrane, cell wall, cytoplasm, and freely floating DNA and ribosomes
- The cell surface may have pili, flagellae, and other features
The Matrix of Life: Weak Interactions in an Aqueous Environment
- Noncovalent interactions:
- Hydrogen bonds
- Dipole-dipole interactions
- Van der Waals forces
- Importance of weak interactions in biomolecular structures
The Role of Water in Biological Processes
- Hydrogen bonding in biological structures
- Water serves as a universal intracellular and extracellular medium due to its ability to form hydrogen bonds and its polar character
- Water is an excellent solvent for ionic compounds
- Hydration of ions in solution
- Nonpolar substances (hydrophobic, lipophilic) have limited solubility in water
Ionic Equilibria
- Brønsted-Lowry definition of acids and bases
- Strong acids and bases, and their conjugate forms
- Buffered solutions:
- Minimize pH changes upon addition of acid or base
- Functioning near the pKa, where the conjugate acid and base are present in nearly equimolar concentrations
Energetics of Life
- Bioenergetics: the study of energy capture, transformation, storage, and utilization in living organisms
- Energy, heat, and work
- Internal energy (U): the total energy of a system
- Thermodynamic systems:
- Isolated: no exchange of energy or matter
- Closed: exchange of energy, but not matter
- Open: exchange of both energy and matter
Free Energy and Chemical Reactions
- Gibbs free energy (G): a function of state that includes both energy and entropy
- Free energy change (ΔG) = ΔH - TΔS
- Favorable processes: negative ΔG
- Unfavorable processes: positive ΔG
- High-energy phosphate compounds:
- ATP and its hydrolysis reactions
- Free energy sources in biological systems
Explore the chemistry of biological processes and substances that store and transmit genetic information. This quiz covers molecular genetics, heredity, and the expression of genetic information in molecular terms.
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