Intro to Biology: Core Principles and Organization

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

Core Principles

• Cell Theory: All living organisms are composed of cells which are the basic units of structure and function
• Gene Theory: Traits are inherited through genes located on chromosomes composed of DNA
• Evolution: Life evolves over time through natural selection
• Homeostasis: Living organisms maintain a stable internal environment

Levels of Organization

• Molecules: Atoms forming molecules, such as DNA and proteins
• Cells: Basic unit of life, with organelles and other structures enclosed by a membrane
• Tissues: Groups of similar cells performing specific functions
• Organs: Structures of different tissues working together
• Organ Systems: Groups of organs that cooperate to perform major bodily functions
• Organisms: Individual living entities
• Populations: Groups of individuals of the same species in an area
• Communities: Populations of different species interacting in the same area
• Ecosystems: Communities interacting with their physical environment
• Biosphere: The sum of all ecosystems on Earth

Cell Biology

• Cells as the basic structural and functional units of life
• Two primary types: prokaryotic and eukaryotic
• Prokaryotic cells (bacteria and archaea) lack a nucleus and other membrane-bound organelles
• Eukaryotic cells (protists, fungi, plants, and animals) have a nucleus and other membrane-bound organelles

Key Cellular Structures

• Plasma Membrane: A selectively permeable barrier separating the cell's interior from the external environment
• Cytoplasm: Fluid-filled space inside the cell with organelles and other components
• Nucleus: Contains the cell's genetic material (DNA) and controls cell activities
• Ribosomes: Synthesize proteins
• Endoplasmic Reticulum (ER): Involved in protein and lipid synthesis
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids
• Mitochondria: Produce energy (ATP) through cellular respiration
• Chloroplasts (in plant cells): Conduct photosynthesis

Genetics

• Genetics studies heredity and variation in organisms
• Genes are segments of DNA that encode functional RNA molecules or proteins
• DNA (deoxyribonucleic acid) carries genetic information
• Chromosomes are structures within the nucleus that contain DNA
• Genotype: The genetic makeup of an organism
• Phenotype: The observable characteristics resulting from genotype and environment interaction
• Inheritance: The passing of traits from parents to offspring

Mendelian Genetics

• Gregor Mendel's pea plant experiments laid the foundation for genetics
• Law of Segregation: Allele pairs separate during gamete formation
• Law of Independent Assortment: Alleles of different genes assort independently during gamete formation

Molecular Genetics

• DNA Structure: Double helix of nucleotides (adenine, guanine, cytosine, and thymine)
• DNA Replication: The process by which DNA is copied
• Transcription: The process by which RNA is synthesized from a DNA template
• Translation: The process by which proteins are synthesized from RNA

Evolution

• Evolution: Change in heritable characteristics of biological populations over successive generations
• Natural Selection: Organisms with advantageous traits are more likely to survive and reproduce
• Adaptation: Enhances organism's survival and reproduction in a specific environment
• Genetic Variation: Differences in genes among individuals within a population
• Mutation: A change in the DNA sequence
• Gene Flow: The movement of genes between populations
• Genetic Drift: Random changes in allele frequencies within a population

Evidence for Evolution

• Fossil Record: Provides evidence of extinct organisms and the sequence of evolutionary changes
• Comparative Anatomy: Similarities in anatomical structures among different species
• Embryology: Similarities in embryonic development among different species
• Molecular Biology: Similarities in DNA and protein sequences among different species
• Biogeography: The study of the distribution of species across geographical areas

Ecology

• Ecology studies the interactions between organisms and their environment
• Population Ecology: Focuses on population size, density, distribution, and growth rate
• Community Ecology: Examines interactions between different species within a community
• Ecosystem Ecology: Studies the flow of energy and nutrients through ecosystems
• Biosphere: The global ecological system integrating all living beings and their relationships

Key Ecological Concepts

• Biotic Factors: Living components of the environment (e.g., plants, animals, bacteria)
• Abiotic Factors: Non-living components of the environment (e.g., temperature, light, water, nutrients)
• Habitat: The natural environment where an organism lives
• Niche: The role and position a species has in its environment
• Food Chain: A sequence of organisms through which energy and nutrients flow
• Food Web: A network of interconnected food chains
• Trophic Levels: The position an organism occupies in a food chain or food web (e.g., producers, consumers, decomposers)
• Symbiosis: Interactions between different species living in close proximity (e.g., mutualism, commensalism, parasitism)

Plant Biology

• Plants are multicellular, eukaryotic organisms in the kingdom Plantae
• Plants perform photosynthesis
• Autotrophs: Organisms that produce their own food, like plants
• Plant cell walls are made of cellulose
• Key structures include roots, stems, leaves, and flowers

Plant Physiology

• Photosynthesis: The process by which plants convert light energy into chemical energy
• Transpiration: The process by which water is transported from the roots to the leaves and evaporates into the atmosphere
• Nutrient Uptake: The absorption of essential nutrients from the soil
• Plant Hormones: Chemical signals that regulate plant growth and development

Animal Biology

• Animals are multicellular, eukaryotic organisms in the kingdom Animalia
• Heterotrophs: Organisms that obtain nutrients from other organisms
• Animals lack cell walls
• They have complex organ systems
• Animals can move and respond to stimuli

Animal Physiology

• Digestion: The process by which food is broken down into smaller molecules for absorption
• Respiration: The process by which oxygen is taken up and carbon dioxide is released
• Circulation: The process by which blood transports oxygen, nutrients, and hormones throughout the body
• Excretion: The process by which waste products are removed from the body
• Nervous System: Enables rapid communication and coordination of body functions
• Endocrine System: Regulates body functions through hormones

Microbiology

• Microbiology is the study of microorganisms, including bacteria, archaea, viruses, fungi, and protists
• Microorganisms are essential for nutrient cycling, decomposition, and various industrial processes
• Some microorganisms are pathogenic and cause disease
• Bacteria and Archaea: Prokaryotic organisms with diverse metabolic capabilities
• Viruses: Non-cellular entities that require a host cell to replicate
• Fungi: Eukaryotic organisms that obtain nutrients by absorption
• Protists: A diverse group of eukaryotic microorganisms

Biotechnology

• Utilizing biological systems, living organisms, or their derivatives, to make or modify products or processes for specific uses
• Genetic Engineering: Modifying the genetic material of organisms to produce desired traits
• Cloning: Creating genetically identical copies of organisms
• Bioremediation: Using microorganisms to clean up pollutants
• Gene Therapy: Introducing genes into cells to treat genetic disorders