Introduction to Biology

Introduction to Biology

• Biology is the scientific study of life, encompassing all living organisms and their interactions.
• It encompasses a vast range of disciplines, including botany, zoology, microbiology, and genetics.
• Key concepts include structure and function, evolution, heredity, and ecology.

Characteristics of Living Organisms

• Living organisms exhibit several defining characteristics:
  • Cellular organization: All living things are composed of cells, the basic units of life.
  • Metabolism: Organisms use energy to carry out various processes.
  • Responsiveness: Organisms react to stimuli from their environment.
  • Growth and development: Organisms increase in size and complexity.
  • Reproduction: Organisms create new individuals of their species.
  • Adaptation: Organisms evolve to better suit their environments over time.
  • Homeostasis: Organisms maintain stable internal conditions.

Levels of Biological Organization

• Biological systems are organized hierarchically from atoms to biospheres.
• Atoms combine to form molecules.
• Molecules form organelles (e.g., mitochondria, chloroplasts).
• Organelles combine to form cells.
• Cells interact to form tissues.
• Tissues combine to form organs.
• Organs work together in organ systems.
• Organ systems form organisms.
• Organisms interact to form populations, communities, and ecosystems.
• Ecosystems are part of the global biosphere.

Cell Theory

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

Basic Chemistry

• Biological systems depend on chemical reactions.
• Water is crucial for life.
• Carbon is the foundation of organic molecules.
• Four major classes of organic molecules essential for life are:
  • Carbohydrates: Provide energy and structural support.
  • Lipids: Store energy, form membranes, and act as hormones.
  • Proteins: Perform diverse functions, including catalysis, transport, and structural support.
  • Nucleic acids (DNA and RNA): Store and transmit genetic information.

Genetics

• Genetics is the study of heredity and how traits are passed from one generation to the next.
• DNA is the molecule carrying genetic information.
• Genes are the basic units of heredity.
• Gene expression: DNA information is used to create proteins.
• Mutations: Changes in DNA sequence can lead to variations.

Evolution

• Evolution is the process of change in species over time.
• Natural selection is a key mechanism of evolution.
• Adaptations are traits that enhance survival and reproduction.
• Speciation is the formation of new species.

Ecology

• Ecology is the study of the interactions between organisms and their environment.
• Key ecological concepts include:
  • Populations: Groups of individuals of the same species.
  • Communities: Groups of different populations.
  • Ecosystems: Communities and their physical environment.
  • Biomes: Large-scale ecosystems.
  • Biodiversity: Variety of life on Earth.
  • Energy flow and nutrient cycling within ecosystems.
  • Interactions between organisms: predation, competition, symbiosis.
  • Impact of humans on the environment.

Physiology

• Physiology studies the functions of organisms and their components.
• Includes the study of organ systems and their functions.
• Exemplified by the functions of the digestive, respiratory, circulatory, and nervous systems, each with specialized parts and mechanisms.

Reproduction & Development

• Reproduction allows for the continuation of a species.
• Asexual and sexual reproduction exist.
• Developmental biology studies the processes of growth and change from a single cell to a complex organism.
• Cell differentiation is crucial for the development of tissues and organs.

Microbiology

• Microbiology is the study of microorganisms, including bacteria, archaea, fungi, protists, and viruses.
• Microorganisms play crucial roles in ecosystems.
• Examples include their influence on nutrient cycles and their role as pathogens in diseases.