Untitled Notes

Definition: Bioenergetics refers to the flow of energy through living systems.
Importance: Every task performed by living organisms requires energy, including:
  - Physical tasks such as heavy labor and exercise.
  - Mental tasks like thinking and processing information.
  - Essential cellular functions:
    - Every cell requires energy to function effectively.
    - Tasks include breaking down or building molecules, signaling between cells, ingesting and breaking down pathogens, and exporting waste and toxins.
    - Energy is also essential for cellular movement.

Energy Requirement: Cells must continually obtain energy to replenish what has been expended.
Metabolic Pathway:
  - Definition: A series of biochemical reactions that convert a substrate molecule through a series of metabolic intermediates, yielding a final product.
  - Types of Metabolic Pathways:
    - Anabolic Pathways: Reactions that involve building larger molecules from smaller ones.
    - Catabolic Pathways: Reactions that involve breaking down larger molecules into smaller ones.
Cellular Metabolism: Encompasses all chemical reactions occurring within a cell.

Definition: The process through which energy from the sun is captured and converted into carbohydrates.
Significance: Photosynthesis powers nearly all ecosystems on Earth.
Location: Occurs within chloroplasts of eukaryotic organisms; in prokaryotes, it takes place in the thylakoid membrane.

Definition: The biochemical process that breaks down sugars and other food molecules in the presence of oxygen to produce carbon dioxide and water.
ATP Generation: Cellular respiration generates ATP, which serves as energy batteries for cells.
Chemical Equation:
$C_6H_{12}O_6 + 6O_2 <br>ightarrow 6CO_2 + 6H_2O + ATP + ext{Heat}$

Energy and Matter: Cells transform energy and matter as they perform work.
  - Energy: The capacity to do work or cause change, existing in various forms:
    - Electrical energy
    - Light energy
    - Heat energy
    - Kinetic Energy: Energy of motion (e.g., speeding bullet, walking person).
    - Potential Energy: Stored energy with potential to perform work, including chemical energy from molecular bonds (e.g., stretched rubber band).

Definition: The study of energy and energy transfer.
Key Principles:
  1. First Law of Thermodynamics: Energy can be transferred and transformed, but cannot be created or destroyed.
  2. Second Law of Thermodynamics: Energy transfers or transformations increase disorder (entropy) with some energy lost as heat.
  - Implication: Energy transfers are not 100% efficient.

Concept: To initiate a chemical reaction, a threshold energy level is needed, known as activation energy (EA).
Function: Even exergonic reactions need a small energy input to overcome this
energy barrier.
- Example: Breaking down glucose molecules requires energy to break bonds between carbon atoms.
Overcoming Activation Energy:
- Options include adding heat or utilizing enzymes that help lower the activation energy barrier.

Role in Reactions: Enzymes promote reactions by:
- Bringing substrates together in optimal orientation.
- Creating an optimal environment (pH, polarity) within the active site.
Mechanism:
- Induced Fit: Enzyme undergoes a mild structural shift upon substrate binding, enhancing the binding arrangement between the enzyme and the substrate's transition state.
- Cycle: Enzyme catalyzes the reaction, releasing products and returning to its original state.

Helper Molecules: Some enzymes require cofactors or coenzymes for activity.
- Cofactors: Inorganic, e.g., metal ions like iron or magnesium. Example: DNA polymerase requires zinc.
- Coenzymes: Organic molecules, often derived from vitamins, that assist enzymatic reactions.