Fundamentals of Biology

• Biology is the scientific study of life.
• Explores the structure, function, growth, origin, evolution, distribution, and taxonomy of living organisms.
• Encompasses a wide range of fields, including botany, zoology, microbiology, genetics, and ecology.
• The fundamental principles unifying biology include cell theory, gene theory, evolution, homeostasis, and thermodynamics.

Cell Theory

• All living organisms are composed of one or more cells.
• The cell is the basic unit of structure and function in organisms.
• All cells arise from pre-existing cells.

Gene Theory

• Traits are inherited through genes.
• Genes are specific sequences of nucleotides on DNA that encode particular proteins.
• Genes are the fundamental units of heredity.

Evolution

• Change in heritable characteristics of biological populations over successive generations.
• Natural selection is a primary mechanism where organisms with advantageous traits are more likely to survive and reproduce.
• Genetic drift, gene flow, and mutation also contribute to evolutionary change.

Homeostasis

• Maintenance of a stable internal environment despite external changes.
• Organisms maintain homeostasis through various regulatory mechanisms, including feedback loops.
• Temperature, pH, and blood glucose levels are examples of factors regulated by homeostasis.

Thermodynamics

• The laws of thermodynamics govern energy transfer in biological systems.
• The first law states that energy is conserved; it cannot be created or destroyed, only transformed.
• The second law states that entropy (disorder) in a closed system tends to increase and living organisms require energy to maintain order.

Hierarchical Organization of Life

• Life is organized in a hierarchical manner, from atoms and molecules to the biosphere.
• The levels of organization include: molecules, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, and the biosphere.
• Emergent properties arise at each level of organization, representing new characteristics not present at the level below.

Chemical Basis of Life

• Carbon is the backbone of organic molecules due to its ability to form stable bonds with other atoms.
• Biological molecules include carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates provide energy and structural support.
• Lipids include fats, oils, and phospholipids; they store energy, insulate, and form cell membranes.
• Proteins perform a wide range of functions, including enzymatic catalysis, transport, and structural support.
• Nucleic acids (DNA and RNA) store and transmit genetic information.

Cell Structure and Function

• Cells are broadly classified as prokaryotic or eukaryotic.
• Prokaryotic cells (bacteria and archaea) lack a nucleus and other membrane-bound organelles.
• Eukaryotic cells (protists, fungi, plants, and animals) contain a nucleus and other membrane-bound organelles such as mitochondria and endoplasmic reticulum.
• The nucleus houses the cell's DNA.
• Mitochondria are responsible for cellular respiration and ATP production.
• The endoplasmic reticulum (ER) is involved in protein and lipid synthesis.
• The Golgi apparatus modifies, sorts, and packages proteins.
• Lysosomes contain enzymes for intracellular digestion.

Metabolism

• Encompasses all chemical reactions that occur within an organism.
• Catabolism is the breakdown of complex molecules into simpler ones, releasing energy.
• Anabolism is the synthesis of complex molecules from simpler ones, requiring energy.
• Enzymes are biological catalysts that speed up metabolic reactions by lowering the activation energy.
• ATP (adenosine triphosphate) is the primary energy currency of the cell.

Photosynthesis

• The process by which plants and other organisms convert light energy into chemical energy.
• Occurs in chloroplasts.
• Uses carbon dioxide and water to produce glucose and oxygen.
• The two main stages are light-dependent reactions and the Calvin cycle.

Cellular Respiration

• The process by which cells break down glucose to generate ATP.
• Occurs in mitochondria.
• Uses glucose and oxygen to produce carbon dioxide, water, and ATP.
• The main stages are glycolysis, the Krebs cycle, and the electron transport chain.

Genetics

• The study of heredity and variation.
• Chromosomes are structures that carry genes.
• DNA (deoxyribonucleic acid) is the genetic material in most organisms.
• RNA (ribonucleic acid) plays various roles in gene expression.
• DNA replication is the process by which DNA is copied.
• Transcription is the process by which RNA is synthesized from DNA.
• Translation is the process by which proteins are synthesized from RNA.
• Mutations are changes in the DNA sequence; they can be spontaneous or induced by mutagens.

Mendelian Genetics

• Gregor Mendel's experiments with pea plants established the basic principles of heredity.
• Mendel's laws include the law of segregation and the law of independent assortment.
• The law of segregation states that allele pairs separate during gamete formation.
• The law of independent assortment states that genes for different traits assort independently during gamete formation.

Molecular Genetics

• Examines the structure and function of genes at the molecular level.
• The central dogma of molecular biology describes the flow of genetic information: DNA → RNA → Protein.
• Gene expression is regulated at various levels, including transcription, translation, and post-translational modification.

Ecology

• The study of the interactions between organisms and their environment.
• Key concepts include populations, communities, ecosystems, and the biosphere.
• A population is a group of individuals of the same species living in the same area.
• A community is a group of interacting populations of different species.
• An ecosystem includes all the living organisms in an area as well as the non-living components of the environment.
• The biosphere is the global sum of all ecosystems.

Population Ecology

• Population size, density, and distribution are important characteristics of populations.
• Population growth is influenced by birth rates, death rates, immigration, and emigration.
• Carrying capacity is the maximum population size that an environment can support.

Community Ecology

• Community structure is influenced by interactions between species, such as competition, predation, mutualism, and parasitism.
• Competition occurs when species compete for the same resources.
• Predation occurs when one species (the predator) eats another species (the prey).
• Mutualism is a relationship in which both species benefit.
• Parasitism is a relationship in which one species (the parasite) benefits at the expense of the other species (the host).

Ecosystem Ecology

• Focuses on the flow of energy and the cycling of nutrients within ecosystems.
• Energy flows through ecosystems from producers (autotrophs) to consumers (heterotrophs).
• Trophic levels represent the position of an organism in a food chain or food web.
• Nutrients cycle through ecosystems via biogeochemical cycles, such as the carbon cycle, nitrogen cycle, and water cycle.

Evolution and Diversity

• Evolution explains the diversity of life on Earth.
• Natural selection, genetic drift, gene flow, and mutation are the major mechanisms of evolution.
• Adaptation is the process by which populations evolve traits that enhance their survival and reproduction in a specific environment.
• Speciation is the process by which new species arise.
• Phylogeny is the evolutionary history of a species or group of related species.
• Taxonomy is the science of classifying and naming organisms.
• The three domains of life are Bacteria, Archaea, and Eukarya.

Plant Biology

• Plants are multicellular, eukaryotic organisms that belong to the kingdom Plantae.
• They are autotrophs and produce their own food through photosynthesis.
• Plant cells have cell walls made of cellulose.
• Key plant structures include roots, stems, leaves, and flowers.
• Roots anchor the plant and absorb water and nutrients from the soil.
• Stems provide support and transport water and nutrients.
• Leaves are the primary sites of photosynthesis.
• Flowers are involved in sexual reproduction.

Animal Biology

• Animals are multicellular, eukaryotic organisms that belong to the kingdom Animalia.
• They are heterotrophs and obtain their food by consuming other organisms.
• Animal cells lack cell walls.
• Animals exhibit a wide range of body plans, including radial symmetry and bilateral symmetry.
• Key animal tissues include epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
• Organ systems, such as the digestive system, respiratory system, circulatory system, and nervous system, perform specialized functions.

Microbiology

• The study of microorganisms, including bacteria, archaea, viruses, fungi, and protists.
• Microorganisms play important roles in nutrient cycling, decomposition, and disease.
• Bacteria are prokaryotic cells that can be beneficial or harmful.
• Viruses are non-cellular entities that require a host cell to replicate.
• Fungi are eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds).
• Protists are a diverse group of eukaryotic microorganisms, including algae and protozoa.