Introduction to Biology

Introduction to Biology

• Biology is the scientific study of life, encompassing various levels of biological organization, from molecules to ecosystems.
• It explores the structure, function, growth, origin, evolution, and distribution of living organisms.
• Key areas of study within biology include:
  • Cell biology: The study of cells, their structure, function, and interactions.
  • Genetics: The study of heredity and variation of traits.
  • Ecology: The study of interactions between organisms and their environment.
  • Evolution: The study of the evolution of life on Earth.

Characteristics of Living Organisms

• Living organisms exhibit several key characteristics:
  • Organization: Living things exhibit highly organized structures at various levels, from molecules and cells to tissues, organs, and organ systems.
  • Metabolism: Includes all chemical reactions within an organism needed to support life, such as the converting of food and energy.
  • Responsiveness: Organisms respond to stimuli or changes in their surroundings.
  • Growth and development: Living things increase in size and complexity throughout their life cycles.
  • Reproduction: Organisms produce offspring, be it sexually or asexually.
  • Adaptation: Organisms evolve and adapt to environmental changes over time.
  • Homeostasis: Maintaining a stable internal environment despite external variations.

Cell Theory

• All living things are composed of cells.
• Cells are basic units of structure and function in living organisms.
• All cells arise from pre-existing cells.

Types of Cells

• Prokaryotic cells: Lack a nucleus and membrane-bound organelles. Examples are bacteria and archaea.
• Eukaryotic cells: Contain a nucleus and membrane-bound organelles. Examples are plant and animal cells.

Biological Molecules

• Four major classes essential to all life:
  • Carbohydrates: Provide energy and structural support.
  • Lipids: Store energy, form membranes, and regulate hormones.
  • Proteins: Essential for various functions, including structural support, catalysis, and transport.
  • Nucleic acids (DNA and RNA): Store and transmit genetic information.

Genetics

• Heredity: The transmission of traits from parents to offspring.
• Genes: The basic units of heredity, located on chromosomes.
• DNA: The molecule that carries genetic instructions.
• RNA: Plays a critical role in protein synthesis.

Ecology

• Study of the interactions between organisms and their environment.
• Focuses on:
  • Population ecology: Studies populations of a single species.
  • Community ecology: Studies interactions between different species in a community.
  • Ecosystem ecology: Studies the flow of energy and matter within an ecosystem.
• Key concepts include:
  • Biomes: Large geographically distinct areas with similar climates and plant communities.
  • Biodiversity: The variety of life in a given area.
  • Food webs and trophic levels
  • Cycles such as carbon and nitrogen.
  • Interactions within an environment (predation, competition, symbiotic relationships).

Evolution

• The process by which populations of organisms change over time.
• Mechanisms of evolution include:
  • Natural selection: The process where organisms with advantageous traits are more likely to survive and reproduce.
  • Genetic variation: The differences in genes between individuals within a population.
  • Mutation: Changes in the DNA sequence that can introduce new traits.
  • Genetic drift: Random changes in gene frequencies within a population.

Classification of Living Organisms

• Hierarchical system of grouping based on shared characteristics:
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

Branches of Biology

• Microbiology: The study of microorganisms.
• Botany: The study of plants.
• Zoology: The study of animals.
• Anatomy: The study of the structure of organisms.
• Physiology: The study of the function of organisms.