Biology and Chemistry Basics

Basic Biological Concepts

• Biology is the study of life, encompassing a vast range of topics from the smallest molecules to the largest ecosystems.
• Living organisms share several key characteristics:
  • Cellular organization: All living things are made up of cells, which are the basic units of life.
  • Metabolism: Living organisms carry out chemical reactions that require energy, such as photosynthesis and respiration.
  • Homeostasis: Living organisms maintain a stable internal environment, despite external changes.
  • Growth and development: Living organisms grow and develop over time.
  • Adaptation: Organisms adapt to their environments over generations through evolution.
  • Response to stimuli: Living organisms respond to changes in their environment.
  • Reproduction: Living organisms produce offspring.

Basic Chemistry Concepts Relevant to Biology

• Matter is anything that has mass and occupies space. It's composed of elements.
• Elements are pure substances that cannot be broken down into simpler substances by chemical means. They are represented by symbols (e.g., C for carbon, O for oxygen).
• Atoms are the smallest units of an element that retain the chemical properties of that element; they are composed of protons, neutrons, and electrons.
• Compounds are substances formed by the chemical combination of two or more different elements in definite proportions. The atoms are held together by chemical bonds.
• Chemical bonds link atoms together. Types include:
  • Ionic bonds: One atom gives up one or more electrons to another atom, forming ions with opposite charges that attract.
  • Covalent bonds: Atoms share one or more pairs of electrons.
  • Hydrogen bonds: A weak attraction between a slightly positive hydrogen atom and a slightly negative atom (e.g., oxygen or nitrogen).
• Chemical reactions involve the breaking and forming of chemical bonds.
• Water is a crucial molecule for life, possessing unique properties that support biological processes:
  • Polarity: Water molecules are polar, leading to hydrogen bonding.
  • High specific heat capacity: Water can absorb significant amounts of heat without a large change in temperature.
  • High heat of vaporization: A lot of energy is required to convert liquid water to water vapor.
  • Excellent solvent: Water dissolves many substances (polar and ionic).
  • Cohesion and adhesion: Water molecules stick to each other and other substances.
• pH and acids/bases:
  • pH measures the concentration of hydrogen ions (H+) in a solution.
  • Acids release H+ ions, while bases accept them. A pH scale measures this.
  • Buffers are substances that resist changes in pH.

Interrelationship of Chemistry and Biology

• Biological molecules: Large molecules, like carbohydrates, proteins, lipids, and nucleic acids, are crucial for life's functions, and their structure and function are determined by chemical properties.
• Chemical reactions are fundamental to all biological processes. For example, photosynthesis involves complex chemical reactions utilizing light energy and carbon dioxide to produce glucose.
• Metabolism is the sum of all chemical reactions in an organism, including those that release energy (catabolism) and those that require energy (anabolism).