Introduction to Cell Biology

• Biology is the scientific study of life
• It explores the structure, function, growth, origin, evolution, distribution, and taxonomy of living organisms
• Biology encompasses a wide range of fields, including anatomy, physiology, cell biology, genetics, ecology, and evolutionary biology

Cell Biology

• The cell is the basic unit of life
• Cell biology studies the structure, function, and behavior of cells
• Key components of cells include the plasma membrane, cytoplasm, and nucleus (in eukaryotic cells)
• The plasma membrane is a selectively permeable barrier that controls the movement of substances into and out of the cell
• The cytoplasm consists of the cytosol (fluid) and organelles
• Organelles are structures within the cell that perform specific functions (e.g., mitochondria for energy production, ribosomes for protein synthesis)
• Eukaryotic cells have a nucleus, which contains the cell's DNA, while prokaryotic cells lack a nucleus
• Cell division processes include mitosis (for growth and repair) and meiosis (for sexual reproduction)

Genetics

• Genetics is the study of heredity and variation in living organisms
• Genes are the basic units of heredity, composed of DNA (deoxyribonucleic acid)
• DNA carries the genetic information that determines an organism's traits
• The structure of DNA is a double helix, with nucleotide bases (adenine, guanine, cytosine, and thymine) pairing specifically (A with T, and C with G)
• The central dogma of molecular biology describes the flow of genetic information: DNA → RNA → Protein
• RNA (ribonucleic acid) is involved in protein synthesis
• Mutations are changes in the DNA sequence that can lead to variations in traits
• Mendelian genetics describes the principles of inheritance, including dominant and recessive alleles
• Genetic engineering involves manipulating an organism's genes to alter its traits

Ecology

• Ecology is the study of the interactions between organisms and their environment
• An ecosystem consists of all the living organisms (biotic factors) in a particular area, as well as the non-living components (abiotic factors) such as air, water, and soil
• Populations are groups of individuals of the same species living in the same area
• Communities are groups of different populations living and interacting in the same area
• Energy flows through ecosystems via food chains and food webs
• Producers (e.g., plants) convert sunlight into chemical energy through photosynthesis
• Consumers (e.g., animals) obtain energy by feeding on other organisms
• Decomposers (e.g., bacteria and fungi) break down dead organic matter, recycling nutrients back into the ecosystem
• Biogeochemical cycles (e.g., carbon cycle, nitrogen cycle) describe the movement of essential elements through ecosystems
• Human activities can have significant impacts on ecosystems, including pollution, deforestation, and climate change

Evolutionary Biology

• Evolution is the process by which populations of organisms change over time
• Natural selection is a mechanism of evolution, where individuals with traits that are better suited to their environment are more likely to survive and reproduce, passing on those traits to their offspring
• Adaptations are traits that enhance an organism's survival and reproduction in a specific environment
• Speciation is the process by which new species arise
• Evidence for evolution includes fossils, comparative anatomy, embryology, and molecular biology
• Phylogeny is the study of the evolutionary relationships between organisms
• The tree of life represents the evolutionary history of all living organisms

Anatomy and Physiology

• Anatomy is the study of the structure of living organisms
• Physiology is the study of the function of living organisms
• Organisms are organized into different levels of complexity: cells, tissues, organs, and organ systems
• Tissues are groups of similar cells that perform a specific function (e.g., muscle tissue, nervous tissue)
• Organs are structures composed of different tissues that work together to perform a specific function (e.g., heart, brain)
• Organ systems are groups of organs that work together to perform a major bodily function (e.g., digestive system, respiratory system)
• Homeostasis is the maintenance of a stable internal environment in the body
• Feedback mechanisms regulate physiological processes to maintain homeostasis