Introduction to Biology

Biology is the scientific study of life.

Characteristics of Life

• Living things share common characteristics, including organization, metabolism, reproduction, growth, response to stimuli, and adaptation.
• Organization: Living things exhibit complex organization, from cells to tissues, organs, and systems.
• Metabolism: All living organisms need energy for maintenance and growth.
• Reproduction: Organisms reproduce to create new individuals, ensuring the continuity of life.
• Growth: Living things grow and develop, increasing in size and complexity.
• Response to stimuli: Organisms respond to changes in their environment.
• Adaptation: Over time, populations of living things adapt to their environment through evolution.

Cell Biology

• The cell is the basic unit of life.
• Cell Theory: All living things are composed of cells, the cell is the basic functional unit of life, and cells arise from pre-existing cells.
• Two main types of cells: prokaryotic and eukaryotic.
• Prokaryotic cells lack a nucleus and other membrane-bound organelles. Bacteria and Archaea are prokaryotes.
• Eukaryotic cells have a nucleus and other membrane-bound organelles. Eukaryotic cells are found in protists, fungi, plants, and animals.
• Key cell structures and their functions include the nucleus (control center), mitochondria (energy production), ribosomes (protein synthesis), endoplasmic reticulum (protein and lipid synthesis), Golgi apparatus (protein modification and sorting), lysosomes (waste disposal), and cell membrane (regulating transport).

Cell Membrane

• Cell membranes are composed of a phospholipid bilayer with embedded proteins.
• The cell membrane is selectively permeable, regulating the movement of substances in and out of the cell.
• Transport mechanisms include diffusion, osmosis, facilitated diffusion, active transport, endocytosis, and exocytosis.

Cell Cycle and Cell Division

• The cell cycle is the series of events that take place in a cell leading to its division and duplication of its DNA (replication) to produce two daughter cells.
• The cell cycle includes interphase (G1, S, G2 phases) and mitosis.
• Mitosis is nuclear division, resulting in two identical daughter cells (prophase, metaphase, anaphase, telophase).
• Meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction.

DNA and Protein Synthesis

• DNA is the genetic material that carries the instructions for building proteins.
• The structure of DNA is a double helix composed of nucleotides, each containing a sugar, phosphate, and nitrogenous base (adenine, guanine, cytosine, thymine).
• DNA replication is the process by which DNA makes copies of itself.
• Transcription is the process by which RNA is synthesized from a DNA template.
• Translation is the process by which proteins are synthesized from RNA.

Genetics

• Genetics is the study of heredity and variation.
• Gregor Mendel's laws of inheritance: Law of segregation and law of independent assortment.
• Terminology: genes, alleles, dominant and recessive traits, genotypes and phenotypes, homozygous and heterozygous.
• Punnett squares are used to predict the outcome of genetic crosses.
• Mutations are changes in the DNA sequence that can lead to genetic variations.
• Genetic engineering and biotechnology: manipulating genes for practical purposes.

Evolution

• Evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection.
• Charles Darwin's theory of evolution by natural selection: variation, inheritance, differential survival, and reproduction.
• Evidence for evolution: fossil record, comparative anatomy, embryology, biogeography, and molecular biology.
• Mechanisms of evolution: natural selection, genetic drift, gene flow, and mutation.
• Speciation is the process by which new species arise.
• Macroevolution: large-scale evolutionary changes over long periods of time.

Classification of Living Things

• Taxonomy is the science of classifying living things.
• Linnaean system of classification: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• The three domains of life: Bacteria, Archaea, and Eukarya.
• The kingdoms of life: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia.

Ecology

• Ecology is the study of the interactions between organisms and their environment.
• Levels of ecological organization: individuals, populations, communities, ecosystems, and the biosphere.
• Population dynamics: population size, density, distribution, growth rate, and limiting factors.
• Community ecology: interactions between different species in a community (competition, predation, symbiosis).
• Ecosystem ecology: energy flow and nutrient cycling in ecosystems.
• Biomes are major types of ecosystems characterized by distinctive climate conditions and plant communities.
• Human impacts on the environment: pollution, deforestation, climate change, and biodiversity loss.

Plant Biology

• Plant structure and function: roots, stems, leaves, flowers, fruits, and seeds.
• Photosynthesis: the process by which plants convert light energy into chemical energy.
• Plant reproduction: sexual and asexual reproduction.
• Plant adaptations to different environments.

Animal Biology

• Animal structure and function: tissues, organs, and systems.
• Animal classification: major phyla (e.g., Chordata, Arthropoda, Mollusca).
• Animal behavior: innate and learned behaviors, social behavior.
• Animal adaptations to different environments.

Human Biology

• Human anatomy and physiology: the structure and function of the human body.
• Major organ systems: skeletal, muscular, nervous, endocrine, cardiovascular, respiratory, digestive, urinary, immune, and reproductive.
• Human health and disease: infectious diseases, genetic disorders, and lifestyle-related diseases.

Viruses

• Viruses are non-cellular entities that consist of a nucleic acid genome surrounded by a protein coat (capsid).
• Viruses can only replicate inside a host cell, using the host's cellular machinery.
• Viral replication cycles: lytic and lysogenic cycles.
• Viruses can cause a wide range of diseases in plants, animals, and humans.