Introduction to Biology

• Biology is the scientific study of life
• It explores the structure, function, growth, origin, evolution, and distribution of living organisms

Core Principles of Biology

• Cell theory states that all living organisms are composed of cells
• Cells are the basic units of structure and function in living organisms
• Genes, made of DNA, are the units of heredity and are passed from parents to offspring
• Evolution is the change in the characteristics of a species over several generations
• Evolution relies on natural selection

Levels of Biological Organization

• Begins with atoms and molecules, progressing through organelles, cells, tissues, organs, and organ systems
• Continues to the organism level, then populations, communities, ecosystems, and the biosphere

Classification of Living Organisms

• The Linnaean system organizes life into a hierarchy of groups (taxa)
• The main ranks are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species
• The three domains of life are Bacteria, Archaea, and Eukarya
• Eukarya includes the kingdoms of Protista, Fungi, Plantae, and Animalia

Chemical Basis of Life

• Life is based on carbon compounds
• Water's unique properties are essential for life (e.g., cohesion, temperature moderation, solvent properties)
• Biological molecules include carbohydrates, lipids, proteins, and nucleic acids

Cell Structure and Function

• Cells are of two types: prokaryotic (lacking a nucleus) and eukaryotic (possessing a nucleus)
• Key organelles in eukaryotic cells include the nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, and chloroplasts (in plant cells)
• The plasma membrane controls the movement of substances into and out of the cell

Metabolism

• Metabolism is the sum of all chemical reactions in an organism
• Enzymes are biological catalysts that speed up chemical reactions
• Cellular respiration breaks down glucose to produce ATP (energy currency of the cell)
• Photosynthesis uses sunlight to convert carbon dioxide and water into glucose and oxygen

Genetics

• Genes are made of DNA and arranged on chromosomes
• DNA replication ensures genetic information is passed on during cell division
• Transcription produces RNA from a DNA template
• Translation synthesizes proteins from RNA

Cell Division

• Mitosis results in two identical daughter cells
• Important for growth and repair
• Meiosis produces four genetically different gametes (sex cells)
• Important for sexual reproduction

Patterns of Inheritance

• Gregor Mendel's work laid the foundation for understanding inheritance patterns
• Genotype is the genetic makeup of an organism
• Phenotype is the observable characteristics
• Alleles are alternate forms of a gene

Evolution

• Natural selection is the primary mechanism of evolution
• Adaptations are traits that enhance survival and reproduction
• Genetic drift, gene flow, and mutation also contribute to evolutionary change
• Speciation is the process by which new species arise

Ecology

• Ecology studies the interactions between organisms and their environment
• Populations are groups of individuals of the same species living in the same area
• Communities are assemblages of different populations
• Ecosystems include all living organisms and the physical environment in a particular area

Plant Biology

• Plants are autotrophs, producing their own food through photosynthesis
• Key plant structures include roots, stems, and leaves
• Vascular tissue (xylem and phloem) transports water and nutrients

Animal Biology

• Animals are heterotrophs, obtaining nutrients by consuming other organisms
• Key animal tissues include epithelial, connective, muscle, and nervous tissue
• Organ systems include the digestive, circulatory, respiratory, excretory, nervous, and endocrine systems

Microbiology

• Microorganisms include bacteria, archaea, protists, fungi, and viruses
• Bacteria are prokaryotic and play crucial roles in nutrient cycling and disease
• Viruses are non-cellular entities that require a host to replicate