M8.L1_How Organisms Obtain Energy_S 2

New Vocabulary

• Energy: The capacity to do work.

• Thermodynamics: The study of the flow and transformation of energy in the universe.

• Metabolism: All the chemical reactions in a cell.

• Photosynthesis: An anabolic pathway where light energy is converted to stored chemical energy.

• Cellular respiration: A catabolic pathway that breaks down organic molecules to release energy.

• Adenosine triphosphate (ATP): The primary biological molecule that provides chemical energy.

Review Vocabulary

• Trophic level: Each step in a food chain or web.

Transformation of Energy

• Cellular processes require energy, essential for performing work.

• Thermodynamics: Focuses on energy's flow and transformation.

Laws of Thermodynamics

First Law of Thermodynamics

• Known as the Law of Conservation of Energy: Energy can change from one form to another, but cannot be created or destroyed.

• Example: Boiling Water on a Stove

  • Heating water involves the conversion of electrical (or chemical) energy into thermal energy. The total energy remains constant, even as its form changes.

Second Law of Thermodynamics

• Energy conversion leads to the increase of entropy (disorder).

• Example: Melting Ice Cube

  • An ice cube absorbs heat in a warm room and melts, illustrating the shift from an ordered solid state to a disordered liquid state.

Energy Sources: Autotrophs and Heterotrophs

• Nearly all energy for life originates from the Sun.

• Autotrophs: Organisms that produce their own food from sunlight or inorganic substances.

• Heterotrophs: Organisms that obtain energy by consuming other organisms.

Metabolism

• Represents all chemical reactions within a cell, organized into pathways:

  • Metabolic Pathway: A series of reactions where the product of one serves as the substrate for the next.

  • Catabolic pathways: Release energy by breaking down larger molecules.

  • Anabolic pathways: Consume energy to synthesize larger molecules.

Key Metabolic Processes

• Photosynthesis: Converts light energy into stored chemical energy (anabolic).

• Cellular respiration: Breaks down organic molecules to release energy (catabolic).

ATP: The Unit of Cellular Energy

• Adenosine Triphosphate (ATP): The crucial molecule for storing and providing chemical energy in cells.

ATP Structure

• Composed of an adenine base, ribose sugar, and three phosphate groups.

ATP Function

• Energy release occurs when the bond between the second and third phosphate groups is broken.