Introduction to Biology

Introduction to Biology

• Biology is the scientific study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy.
• It encompasses a vast array of fields, including botany, zoology, microbiology, and genetics.
• Biological systems are characterized by complexity, organization, and adaptation.

Characteristics of Living Organisms

• Living organisms share several key characteristics:
  • Composed of cells: The basic unit of life.
  • Maintain homeostasis: Stable internal environment despite external changes.
  • Respond to stimuli: Reactions to external or internal changes.
  • Reproduce: Producing offspring, either asexually or sexually.
  • Grow and develop: Increase in size and complexity.
  • Adapt and evolve: Changes over generations to become better suited to their environment.
  • Obtain and use energy: Metabolism.

Key Biological Concepts

• Cell Theory: All living organisms are composed of cells and cell products.
• Evolution: Change in the heritable characteristics of biological populations over successive generations. Driven by natural selection.
• Genetics: The study of genes, heredity, and variation in living organisms. DNA is the fundamental unit.
• Metabolism: All chemical reactions occurring within a living organism to maintain life. Includes anabolism (building) and catabolism (breaking down).
• Ecology: The study of interactions between organisms and their environment. Includes ecosystems, populations, and communities.

Branches of Biology

• Botany: The study of plants.
• Zoology: The study of animals.
• Microbiology: The study of microorganisms, including bacteria, viruses, fungi, and protozoa.
• Genetics: The study of genes, heredity, and variation in living organisms.
• Physiology: The study of the functions of organisms and their parts.
• Ecology: The study of interactions between organisms and their environment.
• Molecular Biology: The study of biological processes at the molecular level, focusing on the structure and function of biomolecules.

Biological Macromolecules

• Carbohydrates: Organic compounds made of carbon, hydrogen, and oxygen. Provide energy and structural support.
• Lipids: Fatty acids, fats, oils, and steroids. Store energy, and form cellular membranes.
• Proteins: Polymers of amino acids. Perform diverse functions such as catalysis (enzymes), transport, and structural support.
• Nucleic Acids: DNA and RNA. Store and transmit genetic information.

Biological Processes

• Photosynthesis: The process used by plants and other organisms to convert light energy into chemical energy in the form of sugars.
• Cellular Respiration: The process by which cells break down glucose to release energy in the form of ATP.
• DNA Replication: The process of making a copy of a DNA molecule.
• Protein Synthesis: The process of creating proteins using the information encoded in DNA.
• Cell Division: The process by which cells reproduce and divide into two daughter cells. Includes mitosis and meiosis.

Biological Systems

• Organ Systems: Interact to perform specific bodily functions. Examples include the digestive, respiratory, or circulatory systems.
• Organisms: Complex entities composed of multiple organ systems. Interact with their environment.
• Populations: Groups of organisms of the same species living in the same area.
• Communities: Different populations interacting within a particular ecosystem.
• Ecosystem: Living organisms interact with each other and their physical environment (abiotic factors like climate and resources).