Introduction to Biology

Introduction to Biology

• Biology is the scientific study of life and living organisms, encompassing their structure, function, growth, evolution, distribution, and taxonomy.
• Biology is a broad field encompassing diverse subdisciplines, including botany, zoology, microbiology, and genetics.
• Key overarching themes in biology include evolution, the structure and function of cells, and the flow of energy and matter.

Levels of Biological Organization

• Atoms combine to form molecules, which assemble into macromolecules (carbohydrates, lipids, proteins, nucleic acids).
• Molecules interact to form organelles, specialized subunits within cells.
• Cells are the fundamental units of life, performing essential life processes.
• Cells group to form tissues, tissues to form organs, organs to form organ systems, and finally, entire organisms.
• Organisms interact within populations, communities, and ecosystems, creating complex biological systems.

Characteristics of Living Organisms

• Living organisms exhibit key characteristics:
  • Organization, the complex arrangement of parts
  • Metabolism, the set of chemical reactions essential for life
  • Growth and development, consistent increases in size and complexity
  • Adaptation, the ability to adjust to environmental changes
  • Reproduction, the ability to produce offspring similar to parents
  • Response to stimuli, the ability to react to external or internal conditions
  • Homeostasis, maintaining a stable internal environment

Cell Theory

• All known living things are composed of one or more cells.
• All living cells arise from pre-existing cells by division.
• The cell is the fundamental unit of structure and function in all living organisms.

Cell Types

• Prokaryotic cells are simpler, lacking a nucleus and membrane-bound organelles (e.g., bacteria, archaea).
• Eukaryotic cells are more complex, containing a nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

Evolution

• Evolution is the change in heritable characteristics of biological populations over successive generations.
• Driven by processes like natural selection, genetic drift, and gene flow.
• Evidence for evolution includes the fossil record, comparative anatomy, molecular biology, and biogeography.

Classification of Organisms

• Taxonomy is the science of classifying organisms.
• A hierarchical system, such as the Linnaean system (Kingdom, Phylum, Class, Order, Family, Genus, Species), organizes organisms based on shared characteristics.

Ecology

• Ecology studies the interactions of organisms with each other and their environment.
• Ecology examines populations, communities, ecosystems, and the biosphere. Key concepts include biodiversity, energy flow, nutrient cycling, and population dynamics.

Genetics

• Genetics studies genes, heredity, and variation in living organisms.
• Includes the study of DNA and genetic inheritance processes (e.g., mitosis, meiosis).
• Genes determine an organism's traits.
• DNA mutations lead to variations and genetic diversity. Modern genetics involves techniques like DNA sequencing and genetic engineering.

Branches of Biology

• Various specializations within biology include:
  • Botany: Study of plants
  • Zoology: Study of animals
  • Microbiology: Study of microorganisms
  • Genetics: Study of heredity and variation
  • Ecology: Study of interactions between organisms and their environment
  • Physiology: Study of functions of organisms and their parts
  • Molecular Biology: Study of biological molecules
  • Biochemistry: Study of chemical processes in living organisms