Podcast
Questions and Answers
What is the primary purpose of metabolic pathways?
What is the primary purpose of metabolic pathways?
Which type of organism is described as being self-sufficient by using CO2 as their main carbon source?
Which type of organism is described as being self-sufficient by using CO2 as their main carbon source?
What is the term for the pathways involved in the synthesis of biomacromolecules?
What is the term for the pathways involved in the synthesis of biomacromolecules?
Which reaction type involves the breaking and making of carbon-carbon bonds?
Which reaction type involves the breaking and making of carbon-carbon bonds?
Signup and view all the answers
What describes the role of heterotrophs in an ecosystem?
What describes the role of heterotrophs in an ecosystem?
Signup and view all the answers
What is a consequence of independent control of anabolism and catabolism in cellular metabolism?
What is a consequence of independent control of anabolism and catabolism in cellular metabolism?
Signup and view all the answers
Which of the following processes is considered exergonic?
Which of the following processes is considered exergonic?
Signup and view all the answers
Which type of reaction involves transferring a chemical group from one molecule to another?
Which type of reaction involves transferring a chemical group from one molecule to another?
Signup and view all the answers
What is the free energy change ($ riangle G$) when ATP is converted to ADP and inorganic phosphate (P)?
What is the free energy change ($ riangle G$) when ATP is converted to ADP and inorganic phosphate (P)?
Signup and view all the answers
Which compound does NOT exhibit high free energy of hydrolysis?
Which compound does NOT exhibit high free energy of hydrolysis?
Signup and view all the answers
How does ATP primarily provide energy during biochemical reactions?
How does ATP primarily provide energy during biochemical reactions?
Signup and view all the answers
Which statement regarding the role of kinases in ATP reactions is correct?
Which statement regarding the role of kinases in ATP reactions is correct?
Signup and view all the answers
What is the ΔG value for the reaction of Glu with ATP to form Glu-6P and ADP?
What is the ΔG value for the reaction of Glu with ATP to form Glu-6P and ADP?
Signup and view all the answers
What does Mg2+ do in relation to ATP and ADP?
What does Mg2+ do in relation to ATP and ADP?
Signup and view all the answers
Which group can ATP NOT donate?
Which group can ATP NOT donate?
Signup and view all the answers
Which process requires energy input for the formation of DNA, RNA, and proteins?
Which process requires energy input for the formation of DNA, RNA, and proteins?
Signup and view all the answers
What is a key characteristic of inorganic phosphate groups in biochemical reactions?
What is a key characteristic of inorganic phosphate groups in biochemical reactions?
Signup and view all the answers
Which of the following accurately describes the relationship between the direct and inverse reaction rates at equilibrium?
Which of the following accurately describes the relationship between the direct and inverse reaction rates at equilibrium?
Signup and view all the answers
What does a negative ΔG value indicate about a biochemical pathway?
What does a negative ΔG value indicate about a biochemical pathway?
Signup and view all the answers
Why do products of ATP hydrolysis tend to be more stable?
Why do products of ATP hydrolysis tend to be more stable?
Signup and view all the answers
What is the relationship between the equilibrium constant (K_eq) and the standard free-energy change (ΔG^0)?
What is the relationship between the equilibrium constant (K_eq) and the standard free-energy change (ΔG^0)?
Signup and view all the answers
In terms of nucleophilic substitution, which group can also serve as a leaving group in biochemical reactions?
In terms of nucleophilic substitution, which group can also serve as a leaving group in biochemical reactions?
Signup and view all the answers
What does the term 'bioenergetics' refer to in the context of biochemical reactions?
What does the term 'bioenergetics' refer to in the context of biochemical reactions?
Signup and view all the answers
What is the role of hexokinase in biochemical reactions mentioned?
What is the role of hexokinase in biochemical reactions mentioned?
Signup and view all the answers
At what pH value is [H2O] considered to be 55.5 M in biochemical contexts?
At what pH value is [H2O] considered to be 55.5 M in biochemical contexts?
Signup and view all the answers
What happens to the energy of ATP when it releases its terminal phosphate group?
What happens to the energy of ATP when it releases its terminal phosphate group?
Signup and view all the answers
What is the role of nucleoside diphosphate kinase in DNA elongation?
What is the role of nucleoside diphosphate kinase in DNA elongation?
Signup and view all the answers
What is the standard Gibbs free energy change (ΔG'o) associated with the reaction involving adenylate kinase?
What is the standard Gibbs free energy change (ΔG'o) associated with the reaction involving adenylate kinase?
Signup and view all the answers
In biological redox reactions, which of the following correctly describes oxidation?
In biological redox reactions, which of the following correctly describes oxidation?
Signup and view all the answers
What form do electrons typically take when transferred in biological systems?
What form do electrons typically take when transferred in biological systems?
Signup and view all the answers
What is produced when ADP and phosphocreatine (PCr) react in muscle cells?
What is produced when ADP and phosphocreatine (PCr) react in muscle cells?
Signup and view all the answers
Which reaction is classified as a reduction?
Which reaction is classified as a reduction?
Signup and view all the answers
What happens during a dehydrogenation reaction in biological systems?
What happens during a dehydrogenation reaction in biological systems?
Signup and view all the answers
Which of the following correctly states the summary of the biological oxidation-reduction process?
Which of the following correctly states the summary of the biological oxidation-reduction process?
Signup and view all the answers
What is indicated by a more positive standard reduction potential (E'o)?
What is indicated by a more positive standard reduction potential (E'o)?
Signup and view all the answers
Which cofactors are involved in the transfer of protons and electrons during oxidation of biochemical substrates?
Which cofactors are involved in the transfer of protons and electrons during oxidation of biochemical substrates?
Signup and view all the answers
What happens to the free energy change (ΔG°') when the reaction progresses to the right?
What happens to the free energy change (ΔG°') when the reaction progresses to the right?
Signup and view all the answers
Which of the following statements is true regarding the oxidation-reduction pair FMN/FMNH2?
Which of the following statements is true regarding the oxidation-reduction pair FMN/FMNH2?
Signup and view all the answers
According to the relationship between ΔE° and ΔG, when does ΔG become less than zero?
According to the relationship between ΔE° and ΔG, when does ΔG become less than zero?
Signup and view all the answers
What indicates that a reaction is favored to proceed forward in terms of standard reactions?
What indicates that a reaction is favored to proceed forward in terms of standard reactions?
Signup and view all the answers
Which statement correctly describes NADH in the context of redox reactions?
Which statement correctly describes NADH in the context of redox reactions?
Signup and view all the answers
What is the correct relationship between acolyte potentials and their ability to function as electron donors or acceptors?
What is the correct relationship between acolyte potentials and their ability to function as electron donors or acceptors?
Signup and view all the answers
Which redox pair would likely have the least tendency to accept electrons?
Which redox pair would likely have the least tendency to accept electrons?
Signup and view all the answers
In the context of the redox reaction, what is the consequence of a negative ΔE?
In the context of the redox reaction, what is the consequence of a negative ΔE?
Signup and view all the answers
Study Notes
Metabolism and Bioenergetics
- Metabolism is a highly coordinated cellular activity involving multi-enzyme systems (metabolic pathways) that perform several functions
- Obtain chemical energy from capturing solar energy or degrading energy-rich nutrients
- Convert nutrients into the cell's own molecules, monomers, etc.
- Synthesize and degrade biomacromolecules required for cellular functions
- Metabolic pathways involve chemical transformations that convert precursors into products via various chemical intermediates called metabolites.
- Organisms are classified based on their carbon source:
- Autotrophs: use CO2 from the atmosphere as their main carbon source, self-sufficient
- Heterotrophs: use complex organic molecules like glucose, dependent on autotrophs and other organisms
- Cell function relies on energy utilization and production:
- Energy Utilization (Anabolism): involves reductive and endergonic processes for biosynthesis, requiring energy input. Examples include muscle contraction, active transport, and thermogenesis
- Energy Production (Catabolism): involves oxidative and exergonic processes which release energy. Examples include metabolic pathways like glycolysis and the citric acid cycle.
- Independent control of anabolism and catabolism is crucial for efficient energy management.
Types of Metabolic Pathways
- Metabolic pathways are classified based on their function:
- Anabolic Pathways: build complex molecules from simpler ones, requiring energy input.
- Catabolic Pathways: break down complex molecules into simpler units, releasing energy.
Chemical Bond Formation and Breakage
- Metabolic reactions mainly involve the making or breaking of carbon-carbon bonds.
- Carbonyl groups are commonly involved in such reactions, due to their ability to stabilize α-carbanions.
Isomerisation and Elimination Reactions
- Isomerisation: involves rearrangement of atoms within a molecule, leading to a change in its structure.
- Elimination Reactions: involve the removal of atoms or groups from a molecule, resulting in the formation of a double bond.
Group Transfer Reactions
- Group transfer reactions involve the transfer of a functional group (e.g., acyl, glycosyl, phosphoryl) from one nucleophile to another, via a nucleophilic substitution reaction.
Inorganic Phosphate Groups in Biochemical Reactions
- Phosphate groups are essential leaving groups in many biochemical reactions.
- Orthophosphate: has a tetrahedral structure similar to water, with charge delocalized across all oxygen atoms.
- Pyrophosphate: can also act as a leaving group in biochemical reactions.
Bioenergetics and Thermodynamics
- The standard free energy change (ΔG⁰) is a measure of the energy change associated with a reaction under standard conditions.
- The relationship between the equilibrium constant (Keq), ΔG⁰, and temperature is given by the equation: ΔG⁰ = -RT ln Keq
- The standard free energy change in biochemistry refers to conditions at pH 7, [H2O] = 55.5 M, and [Mg²⁺] = 1 mM.
Consecutive Reactions - Biochemical Pathways
- The overall free energy change for a pathway is the sum of the ΔG values for each individual reaction within the pathway.
- If the sum of ΔG values is negative, the pathway will proceed in the forward direction.
- ATP hydrolysis has a large and negative ΔG value, making it an important energy source for many biochemical reactions.
Why ATP "Likes" to Lose its Terminal Phosphate
-
Three main factors contribute to this:
- The products of ATP hydrolysis are more stable than ATP itself.
- Products are more easily solvated and therefore more stable.
- Mg²⁺ shields the negative charges in ATP and ADP, making them more stable.
- A fourth reason: The products are more stable than ATP in all cases.
Other High Energy Compounds
- Besides ATP, other compounds with a large free energy of hydrolysis include:
- Creatine phosphate
- Phosphoenolpyruvate
- 1,3-bisphosphoglycerate
- Acetyl-CoA
ATP Provides Energy Through Group Transfers
- ATP does not provide energy simply through hydrolysis, but through group transfer reactions.
- Kinases are enzymes responsible for transferring phosphate groups from high-energy compounds to lower-energy compounds.
Chemical Versatility of ATP
- ATP can donate a variety of groups:
- Phosphoryl
- Pyrophosphoryl
- Adenylyl
- The position of the nucleophilic attack can be determined by ¹⁸O labeling.
Energy for Biosynthesis
- Bond formation (e.g., in DNA, RNA, and proteins) requires energy input.
- This energy is obtained from the breaking of phosphoanhydrides in nucleoside triphosphates (NTPs).
Transphosphorylation Between Nucleotides
- To synthesize NTPs for DNA elongation, all four are needed.
- Their synthesis is achieved by phosphorylation of NDPs using ATP:
- Nucleoside diphosphate kinase: ATP + NDP (or dNDP) → ADP + NTP (or dNTP)
- Adenylate kinase: 2ADP → ATP + AMP
- Creatine kinase: ADP + PCr → ATP + Cr (important for ATP regeneration in muscles)
Biological Oxidation-Reduction Reactions
- Redox reactions are essential for many biochemical processes.
- Organic molecules can exist in various oxidation states, depending on the number of hydrogen atoms and the state of their carbon atoms.
- A typical redox reaction involves the transfer of electrons:
- Oxidation: loss of electrons
- Reduction: gain of electrons
- LEO GER (Lose Electrons Oxidation, Gain Electrons Reduction) helps remember oxidation and reduction roles.
-
Biological Oxidation-Reduction Reactions :
- Often involve dehydrogenations (loss of hydrogen)
- Protons (H+) and electrons (e-) are transferred to and from cofactors: NAD+, FAD, NADH, FADH2, etc.
Redox Pairs and Standard Reduction Potential
- Redox Pair: an oxidation reaction is always accompanied by a reduction reaction.
-
Standard Reduction Potential (Eo'): measures the tendency of a species to gain electrons.
- More positive Eo', the stronger the oxidizing agent, with a greater tendency to accept electrons.
- More negative Eo', the greater the tendency to lose electrons, making it a stronger reducing agent.
- ΔGo': the change in free energy is directly related to ΔEo': ΔEo= Eo for oxidation semireaction + Eo reduction semireaction.
Calculating Free Energy Change in Redox Reactions
- The change in free energy (ΔG) for a redox reaction can be calculated from the difference in standard reduction potentials (ΔEo) using the equation:
- ΔG = -nFΔEo
- n: number of electrons transferred.
- F: Faraday's constant.
- For a reaction to be spontaneous (ΔG < 0), ΔEo must be positive.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on metabolism and bioenergetics, focusing on multi-enzyme systems, metabolic pathways, and energy utilization. This quiz covers the differences between autotrophs and heterotrophs and the chemical transformations involved in cellular functions. Dive into the essential concepts that drive cellular activity and energy production.
