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Questions and Answers
What defines a catabolic reaction in metabolic processes?
How do enzymes increase the speed of biochemical reactions?
Which conditions can affect enzyme activity according to their special features?
What is a primary characteristic of enzymes that makes them crucial in metabolic reactions?
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What is the role of the enzyme carbonic anhydrase in the body?
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What is the primary role of ATP in living cells?
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During which type of reaction does a molecule gain electrons?
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Which energy carrier molecule is specifically used in photosynthesis?
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What happens to electrons during cellular respiration?
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What is the relationship between oxidation and reduction in biological systems?
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Study Notes
Energy in Living Systems
- Metabolism involves energy transfer and adheres to the Laws of Thermodynamics.
- Biological systems are open systems that exchange energy with surroundings.
- Key laws relevant in biology:
- First Law: Energy cannot be created or destroyed, only transformed.
- Second Law: Reactions increase disorder (entropy), often noted as heat release.
Types of Reactions
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Catabolic Reactions:
- Involve conversion of reactants to smaller products.
- Release energy and can occur spontaneously, though enzymes often assist.
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Anabolic Reactions:
- Create larger molecules from smaller ones.
- Require energy input, hence are not spontaneous.
Enzymes
- Enzymes are biological catalysts that facilitate chemical reactions by lowering activation energy.
- Each enzyme has a specific function, determined by its 3-dimensional shape.
- Substrates bind at the active site, often undergoing an "induced fit" to enhance the reaction.
- Enzymes can be reused; they are not consumed in reactions and typically have names ending in –ase.
Carbonic Anhydrase
- An enzyme crucial for expelling carbon dioxide from respiration.
- Catalyzes the reaction of CO2 with water to form bicarbonate, which is transported in blood.
- Bicarbonate is converted back to CO2 in the lungs for exhalation.
Factors Affecting Enzyme Activity
- Enzyme functions are influenced by environmental conditions such as pH, temperature, and concentration of salts or cofactors.
- Vitamins act as coenzymes, essential for enzyme activities.
Energy Carrier Molecules
- Cells must efficiently store energy; they rely on ATP as the primary energy currency.
- ATP stores energy in high-energy phosphate bonds, releasing it upon hydrolysis.
- Other carriers include NADH and FADH2 for cellular respiration, and NADPH for photosynthesis.
Electrons in Biological Systems
- Electrons, as they move, represent energy; but they must be associated with hydrogen to be transferred within cells.
- Redox reactions involve the coupling of oxidation (loss of electrons) and reduction (gain of electrons).
Cellular Respiration Overview
- A series of catabolic reactions that convert substrates like glucose into ATP, which powers cellular activities.
- Involves three main steps: Glycolysis, Citric Acid Cycle (Krebs Cycle), and Oxidative Phosphorylation.
Glycolysis
- Occurs in the cytoplasm; converts glucose into pyruvate, producing a net gain of 2 ATP and 2 NADH.
- Does not require oxygen (anaerobic).
Citric Acid Cycle
- Takes place in mitochondrial matrix; processes pyruvate to generate energy carriers (NADH, FADH2) and ATP.
- Each pyruvate results in the release of CO2 and formation of energy carriers; cycle turns twice per glucose molecule.
Oxidative Phosphorylation
- Happens in mitochondrial inner membranes using an electron transport chain (ETC).
- Goal is to produce ATP by harnessing the energy from electron transfers; O2 is vital as the final electron acceptor.
Importance of Oxygen
- Essential for ATP production; without oxygen, respiratory processes stall, leading to cell death.
- Poisons like carbon monoxide can impede oxygen's function in cellular respiration.
Variations on Cellular Respiration
- Anaerobic Respiration: Occurs without O2, using alternative electron acceptors (nitrates, sulfates) resulting in lower energy yield.
- Fermentation: Anaerobic process that produces minimal ATP without using the ETC; sufficient for cell survival in low oxygen conditions.
Conclusion
- Energy is a cornerstone of life; organisms derive energy from photosynthesis or food, harnessing ATP for cellular functions and metabolic processes.
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Description
Dive into the fascinating world of energy in living systems with this quiz. Explore metabolism, thermodynamics, and the roles of enzymes in biological reactions. Understand the differences between catabolic and anabolic reactions and how they contribute to the energy dynamics of cells.
