Metabolism and Energy Concepts

Metabolism and Energy

• Metabolism encompasses all chemical reactions in organisms, crucial for energy transformation during activities like studying or building structures.
• Chemical reactions can absorb energy; these endergonic reactions store energy from an external source, used in processes like photosynthesis, creating glucose and oxygen from sunlight, water, and carbon dioxide.
• Exergonic reactions release energy; products have less energy than reactants, as seen in cellular respiration, which breaks down glucose to release stored energy.

Chemical Reactions Dynamics

• Reactions can progress in both directions, creating metabolic pathways where products of one reaction serve as reactants for another, such as in DNA replication.
• Energy in biological systems is fundamental for processes like reproduction, movement, and substance transport.

States of Energy

• Energy exists as potential (stored) or kinetic (active).
• ATP (adenosine triphosphate) serves as a temporary energy storage molecule, essential for cellular functions. Cells store potential energy within chemical bonds.

Thermodynamics Principles

• The First Law of Thermodynamics states energy cannot be created or destroyed; it only changes forms.
• Photosynthesis exemplifies energy conversion, producing sugar (chemical energy) from light energy and forming DNA structures vital for reproduction.

Electron Transport and Reactions

• Electrons are key for energy transfer between molecules through redox (oxidation-reduction) reactions; oxidation involves electron loss, while reduction involves electron gain.
• These redox reactions often release energy and occur simultaneously.

Role of ATP

• ATP functions as the energy currency of cells, produced in mitochondria and utilized across all life forms, including plants and animals.
• During ATP recycling, it converts to ADP (adenosine diphosphate) and an inorganic phosphate through energy input, which can then regenerate ATP.

Enzymatic Function

• Enzymes lower activation energy, facilitating chemical reactions by organizing substrates and altering their shape for better fit.
• The active site of enzymes binds substrates, forming an enzyme-substrate complex which speeds up reactions.

Cofactors and Coenzymes

• Enzymatic reactions often require cofactors—substances that assist enzymes, which can return to their original state post-reaction.
• Coenzymes, a type of organic molecule cofactors, include vitamins essential for various enzymatic functions.

Regulation of Enzyme Activity

• Negative feedback loops regulate enzymatic activity by inhibiting reactions when product levels are high, ensuring homeostasis in biological systems.
• Inhibitors can block enzyme function, disrupting normal metabolic processes.

Gas Exchange and Osmosis

• Simple diffusion allows gases like O2 and CO2 to move across membranes, creating concentration gradients that facilitate constant flow and exchange between blood and cells.
• Osmosis involves the movement of water across selectively permeable membranes, with water moving from areas of high to low concentration, affected by the tonicity of surrounding solutions, such as hypertonic environments like the Dead Sea.