Core Principles and Branches of Biology

Core Principles of Biology

• Biology recognizes cells as the basic unit of life.
• Genes are the basic unit of heredity.
• Evolution explains the unity and diversity of life.
• Living organisms exist in an ecosystem.
• Homeostasis is the maintenance of a stable internal environment.

Branches of Biology

• Biochemistry examines the chemical processes within and relating to living organisms.
• Botany studies plants, including their physiology, structure, genetics, ecology, distribution, classification, and economic importance.
• Cell biology examines the structure and function of cells.
• Ecology studies the interactions of living organisms with each other and their environment.
• Evolutionary biology examines the evolutionary processes that produced the diversity of life on Earth.
• Genetics studies heredity and variation in organisms.
• Microbiology studies microorganisms, including bacteria, viruses, fungi, and protozoa.
• Molecular biology studies the molecular basis of biological activity.
• Physiology studies the functions and mechanisms of living organisms and their parts.
• Zoology studies animals, including their physiology, structure, genetics, ecology, behavior, classification, and distribution.

Characteristics of Life

• Living organisms exhibit order in their internal structure and function.
• Reproduction is a fundamental characteristic of life; organisms reproduce to generate offspring.
• Growth and Development: Living organisms grow and develop according to specific genetic instructions.
• Energy Processing: Life requires energy and organisms process energy through metabolic processes.
• Response to the Environment: Organisms respond to stimuli in their environment.
• Regulation: Organisms maintain internal conditions via regulatory mechanisms (homeostasis).
• Evolutionary Adaptation: Life evolves over time through adaptation to the environment.

Cell Structure and Function

• The cell is the basic unit of life.
• Cell Theory: All living organisms are composed of one or more cells, the cell is the basic unit of structure and organization in organisms, and cells arise from pre-existing cells.
• Prokaryotic Cells: Lack a nucleus or other membrane-bound organelles; Bacteria and Archaea.
• Eukaryotic Cells: Contain a nucleus and other membrane-bound organelles; protists, fungi, plants, and animals.
• 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 to produce sugars.
• Plasma Membrane: Outer boundary of the cell, regulates the movement of substances in and out of the cell.

Genetics

• Genetics is the study of heredity and variation in organisms.
• Genes: Units of heredity made of DNA, carrying information for specific traits.
• DNA: Deoxyribonucleic acid, the molecule that carries genetic information.
• Chromosomes: Structures within the cell's nucleus that are made of DNA and protein.
• Genotype: The genetic makeup of an organism.
• Phenotype: The observable characteristics of an organism, resulting from the interaction of its genotype with the environment.
• Inheritance: The process by which traits are passed from parents to offspring.
• Mendelian Genetics: Principles of inheritance described by Gregor Mendel.
• Dominant and Recessive Alleles: Dominant alleles mask the expression of recessive alleles.
• Homozygous and Heterozygous: Homozygous individuals have two identical alleles for a gene, while heterozygous individuals have two different alleles.
• Punnett Square: A diagram used to predict the genotypes and phenotypes of offspring.
• Mutations: Changes in the DNA sequence; can be spontaneous or induced by external factors.

Evolution

• Evolution is the change in the heritable characteristics of biological populations over successive generations.
• Natural Selection: A mechanism of evolution in which individuals with advantageous traits are more likely to survive and reproduce.
• Adaptation: Traits that enhance an organism's survival and reproduction in a specific environment.
• Genetic Variation: Differences in genes among individuals within a population.
• Mutation: Random changes in DNA that can introduce new alleles into a population.
• Gene Flow: The movement of genes between populations.
• Genetic Drift: Random changes in allele frequencies due to chance events.
• Evidence for Evolution: Fossil record, comparative anatomy, embryology, biogeography, molecular biology.
• Speciation: The process by which new species arise.
• Allopatric Speciation: The formation of new species due to geographic isolation.
• Sympatric Speciation: The formation of new species without geographic isolation.

Ecology

• Ecology is the study of the interactions between organisms and their environment.
• Ecosystem: A community of living organisms interacting with their physical environment.
• Biotic Factors: Living components of an ecosystem (e.g., plants, animals, microorganisms).
• Abiotic Factors: Non-living components of an ecosystem (e.g., temperature, sunlight, water, nutrients).
• Population: A group of individuals of the same species living in the same area.
• Community: A group of interacting populations of different species in the same area.
• Energy Flow: The transfer of energy through an ecosystem.
• Food Chain: A linear sequence of organisms through which nutrients and energy pass as one organism eats another.
• Food Web: A complex network of interconnected food chains in an ecosystem.
• Trophic Levels: The position an organism occupies in a food chain or food web (e.g., producers, primary consumers, secondary consumers).
• Producers: Autotrophs that produce their own food through photosynthesis or chemosynthesis.
• Consumers: Heterotrophs that obtain energy by feeding on other organisms.
• Decomposers: Organisms that break down dead organic matter and release nutrients back into the environment.
• Nutrient Cycling: The movement of essential nutrients through an ecosystem (e.g., carbon cycle, nitrogen cycle, water cycle).
• Biomes: Large geographic areas characterized by specific climate conditions, animal populations, and plant species (e.g., tropical rainforest, desert, grassland, tundra).
• Population Ecology: Studies the factors that affect population size and density.
• Community Ecology: Studies the interactions between different species in a community.
• Ecosystem Ecology: Studies the flow of energy and cycling of nutrients in ecosystems.
• Conservation Biology: Studies the preservation and management of biodiversity.

Anatomy and Physiology

• Anatomy is the study of the structure of living organisms.
• Physiology is the study of the function of living organisms and their parts.
• Levels of Organization: Cells, tissues, organs, organ systems, organism.
• Tissues: Groups of similar cells performing a specific function; epithelial, connective, muscle, and nervous tissues.
• Epithelial Tissue: Covers body surfaces and lines body cavities and organs.
• Connective Tissue: Supports, connects, and separates different types of tissues and organs in the body (e.g., bone, cartilage, blood).
• Muscle Tissue: Specialized for contraction and movement (e.g., skeletal, smooth, and cardiac muscle).
• Nervous Tissue: Transmits electrical signals throughout the body (e.g., brain, spinal cord, nerves).
• Organ: A structure composed of different tissues working together to perform a specific function (e.g., heart, lungs, stomach).
• Organ System: A group of organs working together to perform a complex function (e.g., digestive system, respiratory system, circulatory system).
• Skeletal System: Provides support, protection, and movement (e.g., bones, cartilage, ligaments).
• Muscular System: Enables movement, maintains posture, and generates heat (e.g., skeletal muscles, smooth muscles, cardiac muscle).
• Nervous System: Controls and coordinates body functions (e.g., brain, spinal cord, nerves).
• Endocrine System: Regulates body functions through the secretion of hormones (e.g., glands, hormones).
• Cardiovascular System: Transports blood, oxygen, nutrients, and waste products throughout the body (e.g., heart, blood vessels, blood).
• Respiratory System: Exchanges gases between the body and the environment (e.g., lungs, trachea, diaphragm).
• Digestive System: Breaks down food and absorbs nutrients (e.g., mouth, esophagus, stomach, intestines).
• Urinary System: Filters waste products from the blood and eliminates them in urine (e.g., kidneys, bladder).
• Immune System: Protects the body against pathogens and foreign substances (e.g., white blood cells, antibodies).
• Reproductive System: Enables reproduction (e.g., ovaries, testes).

Microbiology

• Microbiology is the study of microorganisms, including bacteria, viruses, fungi, and protozoa.
• Bacteria: Prokaryotic, single-celled organisms.
• Archaea: Prokaryotic microorganisms distinct from bacteria.
• Viruses: Acellular infectious agents composed of nucleic acid surrounded by a protein coat.
• Fungi: Eukaryotic organisms, including yeasts, molds, and mushrooms.
• Protozoa: Eukaryotic, single-celled microorganisms.
• Microbial Growth: Factors affecting microbial growth include temperature, pH, oxygen, nutrients, and water availability.
• Microbial Metabolism: Metabolic processes in microorganisms (e.g., fermentation, respiration, photosynthesis).
• Microbial Genetics: Study of genes and heredity in microorganisms.
• Microbial Ecology: Study of the interactions of microorganisms with each other and their environment.
• Pathogens: Microorganisms that can cause disease.
• Antibiotics: Medications used to treat bacterial infections.
• Antivirals: Medications used to treat viral infections.
• Antifungals: Medications used to treat fungal infections.
• Beneficial Microbes: Microorganisms that have beneficial effects on humans and the environment (e.g., probiotics, nitrogen-fixing bacteria).