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Questions and Answers
Which term describes reactions that release energy, such as digestion?
Which term describes reactions that release energy, such as digestion?
What type of reaction involves the formation of bonds between molecules and requires an input of energy?
What type of reaction involves the formation of bonds between molecules and requires an input of energy?
Which of the following best describes catabolic reactions?
Which of the following best describes catabolic reactions?
What is the primary function of enzymes in metabolic reactions?
What is the primary function of enzymes in metabolic reactions?
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In terms of free energy, what does a positive change in ΔG indicate about a reaction?
In terms of free energy, what does a positive change in ΔG indicate about a reaction?
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Which of the following correctly describes the role of ATP in cellular metabolism?
Which of the following correctly describes the role of ATP in cellular metabolism?
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What is the significance of the third phosphate group in ATP?
What is the significance of the third phosphate group in ATP?
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What type of reaction is involved in the phosphorylation of AMP to create ADP?
What type of reaction is involved in the phosphorylation of AMP to create ADP?
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Why is ATP considered an excellent energy donor?
Why is ATP considered an excellent energy donor?
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During which process is energy captured and stored by ATP?
During which process is energy captured and stored by ATP?
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What happens to ATP when it transforms into ADP?
What happens to ATP when it transforms into ADP?
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How do enzymes affect the activation energy of reactions?
How do enzymes affect the activation energy of reactions?
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What is the role of a substrate in enzyme activity?
What is the role of a substrate in enzyme activity?
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Which factor is NOT known to affect enzyme function?
Which factor is NOT known to affect enzyme function?
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What is a characteristic of biological catalysts?
What is a characteristic of biological catalysts?
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Study Notes
Metabolism & Enzymes
- Life is built on chemical reactions, transforming energy from one form to another.
- Organic molecules are transformed into ATP and other organic molecules.
Metabolism
- Chemical reactions of life form bonds between molecules, such as dehydration synthesis or synthesis, which are anabolic reactions.
- Breaking bonds between molecules, like hydrolysis or digestion, are catabolic reactions.
Examples
- Dehydration synthesis (synthesis): Joining molecules together by removing water. An illustration shows this with monomers combining to form a polymer, assisted by an enzyme.
- Hydrolysis (digestion): Breaking down molecules by adding water. An illustration shows this with a polymer being broken down into monomers, also assisted by an enzyme.
Chemical Reactions & Energy
- Some reactions release energy (exergonic). Examples include digesting polymers (hydrolysis = catabolism).
- Some reactions require energy input (endergonic). Examples include building polymers (dehydration synthesis = anabolism).
Endergonic vs. Exergonic Reactions
- Exergonic reactions release energy, associated with digestion. A diagram shows a graph illustrating energy release and the process.
- Endergonic reactions require energy, associated with synthesis. A diagram shows a graph illustrating energy input or investment, needed to carry out the reaction.
- AG = change in free energy, representing the ability to do work.
Energy & Life
- Organisms require energy to live.
- Energy is obtained by coupling exergonic reactions with endergonic reactions.
Living Economy
- Organisms obtain energy by consuming high-energy organic molecules (carbohydrates, lipids, proteins, nucleic acids).
- Catabolism is the breakdown of these molecules to release energy.
- Energy is captured and used by cells.
- Cells need a way to transfer energy, this is the currency of energy – ATP.
- ATP is needed short-term energy molecule for energy storage.
ATP
- ATP (adenosine triphosphate) is a modified nucleotide, a fundamental component of nucleotides.
- ATP is formed by adding phosphates to ADP (adenosine diphosphate).
- Adding phosphates to ADP is an endergonic reaction requiring energy.
- ATP stores energy in high-energy phosphate bonds.
How does ATP store energy?
- Each negative phosphate group (PO₄) makes it more difficult to add a phosphate to the chain, thus storing more energy with each added phosphate to the chain.
- The third phosphate group is the hardest to keep bonded to the molecule and thus the source of the most energy.
- Bonds of negative P groups are unstable and easily broken, releasing energy.
How does ATP transfer energy?
- ATP releases energy when it's converted into ADP (adenosine diphosphate) and a free phosphate group (Pi).
- The energy released during this process (ΔG = -7.3 kcal/mole) fuels other reactions.
- Released P₁ can be transferred to other molecules, providing the energy to destabilize the other molecules.
ATP/ADP Cycle
- The ATP/ADP cycle is essential for storing and transferring energy.
- Organisms can't store ATP because it's too reactive and easily loses its phosphate.
- Carbohydrates and fats are used for longer-term energy storage.
Activation Energy
- Breaking down large molecules requires an initial input of energy, activation energy.
- Large biomolecules are stable and absorb energy to break bonds.
- Activation energy is needed to get reactions to continue over the energy hill in a reaction.
Reducing Activation Energy
- Catalysts, like enzymes, reduce the activation energy needed to start a reaction.
- Catalyzed reactions need less activation energy than un-catalyzed reactions.
Enzymes
- Enzymes are biological catalysts (proteins or RNA), increasing reaction rates without being consumed.
- They reduce activation energy.
- They don't change the overall energy released (ΔG) of the reaction.
- Enzymes also control reactions by being extremely specific for each substrate.
- Enzymes are present in thousands of different types within cells to control life's reactions.
Enzymes Vocabulary
- Substrate: The reactant that binds to the enzyme.
- Enzyme-substrate complex: A temporary association formed when the substrate binds to the enzyme.
- Product: The end result of the reaction.
- Active site: The enzyme's catalytic site; the substrate fits into the active site.
Properties of Enzymes
- Reaction specific: Each enzyme works with a specific substrate.
- Not consumed: A single enzyme can catalyze thousands of reactions per second.
- Unaffected by the reaction.
- Affected by cellular conditions (temperature, pH, salinity).
Naming Conventions
- Enzymes are named based on the reaction they catalyze (e.g., sucrase breaks down sucrose, proteases break down proteins).
Factors Affecting Enzyme Function
- Enzyme concentration: Higher concentrations lead to increased reaction rates.
- Substrate concentration: Reaction rates eventually plateau with increasing substrate concentrations.
- Temperature: Different temperatures affect different enzymes.
- pH: Each enzyme has an optimal pH range for activity.
- Salinity: Changes in salt concentration can affect enzyme activity.
- Activators: Molecules that help enzymes work better.
- Inhibitors: Molecules that reduce or stop enzyme activity.
Compounds which help enzymes
- Activators (Cofactors): Non-protein, organic molecules or inorganic ions that are essential for enzyme activity.
- Coenzymes: Organic molecules that bind temporarily or permanently to enzymes to promote reactions. Many vitamins function as coenzymes.
Allosteric Regulation
- Enzymes can be regulated by allosteric regulation, which changes their shape by regulatory molecules. This can either activate or inhibit enzyme activity.
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Description
Explore the vital processes of metabolism and enzyme function in this quiz. Learn about anabolic and catabolic reactions, including dehydration synthesis and hydrolysis, and how these chemical reactions transform energy. Test your understanding of how life sustains itself through these crucial biochemical pathways.
