Introduction to Biology

Introduction to Biology

• Biology is the scientific study of life and living organisms.
• It encompasses various disciplines, including botany, zoology, microbiology, and genetics.
• Key aspects include cells, genetics, evolution, ecology, and the structure and function of organisms.
• Life is characterized by several defining features, including:
  • Organization: Living organisms are arranged in complex structures.
  • Metabolism: The chemical processes within organisms to maintain life.
  • Growth and development: Organisms grow and change over their lifetime.
  • Reproduction: Organisms produce offspring, passing on genetic material.
  • Response to stimuli: Living things react to changes in their environment.
  • Homeostasis:Maintaining internal balance.
  • Adaptation: Organisms adapt to their environment over generations.

Levels of Biological Organization

• Biological organization encompasses various hierarchical levels, from the smallest to the largest.
• Atoms combine to form molecules.
• Molecules form macromolecules, which contribute to cell structure and functions.
• Cells are the basic units of life, forming tissues.
• Tissues combine to form organs.
• Organs collaborate in organ systems.
• Organ systems form a multicellular organism (e.g., animal or plant).
• Organisms interact in populations, communities, and ecosystems.
• Finally, the biosphere consists of all interconnected ecosystems on Earth.

Basic Chemistry for Biology

• Carbon is a key element in living matter, forming the backbone of many biological molecules.
• Water is essential for life; its properties include polarity, high specific heat, and ability to act as a solvent.
• Four major classes of biological macromolecules: carbohydrates, lipids, proteins, and nucleic acids.
  • Carbohydrates: Primary energy source; structural components.
  • Lipids: Store energy, insulation; component of cell membranes.
  • Proteins: Diverse functions — structural, enzymatic, transport, etc.
  • Nucleic acids (DNA and RNA): Carry genetic information.

Cell Structure and Function

• Cells are the fundamental units of life; they are diverse in structure and function.
• There are two main types of cells: prokaryotic and eukaryotic.
• Prokaryotic cells are smaller and simpler, lacking membrane-bound organelles.
• Eukaryotic cells are larger and more complex, possessing membrane-bound organelles (e.g., nucleus, mitochondria).
• Key organelles:
  • Nucleus: Stores genetic material (DNA).
  • Mitochondria: Powerhouse of the cell, performing cellular respiration.
  • Ribosomes: Synthesize proteins.
  • Endoplasmic reticulum (ER): Involved in protein synthesis and lipid metabolism.
  • Golgi apparatus: Processes and packages proteins.
  • Vacuoles: Storage compartments

Cellular Processes

• Cellular respiration: The process by which cells break down glucose to release energy.
• Photosynthesis: The process by which plants and some other organisms convert light energy into chemical energy.
• Cell division: Mitosis and meiosis are critical for growth, repair, and reproduction.
  • Mitosis: Cell division for growth and repair.
• Meiosis: Cell division for sexual reproduction.

Genetics

• Hereditary information is passed through DNA.
• DNA is organized into genes, which code for specific proteins.
• Genes can be expressed (turned on) or repressed (turned off).
• Mutation is a change in the DNA sequence.
• Chromosomes are structures that organize DNA in cells.

Biological Diversity

• The vast array of life on Earth encompasses numerous species.
• Biological diversity (biodiversity) is the variety of life at all levels of biological organization.
• Evolutionary processes have led to the diversity of species seen today.
• Darwin's theory of evolution by natural selection: Species change over time due to inheritable variations that affect survival/reproduction.
• Adaptation: Organisms adapt to their environment over generations.