Cell Biology for NEET

• Biology is the study of life and living organisms
• It encompasses their structure, function, growth, origin, evolution, and distribution
• NEET (National Eligibility cum Entrance Test) refers to an entrance examination in India for students who wish to study undergraduate medical courses

Cell Biology

• Cell biology concerns the study of cells, specifically their structure, function, and behavior
• Cell theory posits that all living organisms are composed of cells, with the cell serving as the basic unit of life, and all cells originate from pre-existing cells
• Cells are broadly classified into prokaryotic and eukaryotic types
• Prokaryotic cells lack a true nucleus and membrane-bound organelles
• Eukaryotic cells possess a nucleus and membrane-bound organelles
• Key cell organelles include:
  • Nucleus: Contains genetic material (DNA) and controls cell activities
  • Endoplasmic Reticulum (ER): Plays a role in protein and lipid synthesis
    • Rough ER (RER) has ribosomes attached and deals with protein synthesis
    • Smooth ER (SER) lacks ribosomes and participates in lipid synthesis and detoxification
  • Golgi apparatus: Modifies, sorts, and packages proteins and lipids
  • Lysosomes: Contain enzymes for intracellular digestion
  • Mitochondria: The site of cellular respiration and ATP production
  • Chloroplasts: (in plant cells) facilitate photosynthesis
  • Ribosomes: Serve as the site of protein synthesis
  • Cell membrane: Encloses the cell and regulates the movement of substances in and out
  • Cell wall: (in plant cells) offers support and protection
  • Cytoskeleton: Furnishes structural support and facilitates cell movement
• Cell division includes:
  • Mitosis: Cell division that results in two identical daughter cells
    • Consists of prophase, metaphase, anaphase, and telophase
  • Meiosis: Cell division results in four genetically different daughter cells (gametes)
    • Includes Meiosis I (reductional division) and Meiosis II (equational division)

Genetics

• Genetics involves studying heredity and variation in living organisms
• Genes, composed of DNA, are units of heredity
• DNA (deoxyribonucleic acid) acts as the genetic material that carries instructions for the development and function of living organisms
• RNA (ribonucleic acid) participates in protein synthesis
• Chromosomes are structures containing DNA
• The human genome consists of 23 pairs of chromosomes
• Mendelian genetics:
  • Gregor Mendel's laws of inheritance:
    • Law of segregation: Allele pairs separate when gametes are formed
    • Law of independent assortment: Alleles of different genes assort independently during gamete formation
  • Monohybrid cross: A cross involving one trait
  • Dihybrid cross: Involves two traits
• Genetic mutations are changes in the DNA sequence
  • This can be spontaneous or induced, harmful, beneficial, or neutral
• Genetic engineering involves the manipulation of genes
• Recombinant DNA technology exists
• Polymerase Chain Reaction (PCR) can occur
• Gene therapy can be used
• Genomics refers to the study of genomes
• There is the Human Genome Project

Ecology

• Ecology focuses on the interactions between organisms and their environment
• Ecosystem: A community of living organisms and their physical environment act as a functional unit
• Biome: A large geographic area characterized by specific climate and vegetation
• Key ecological concepts:
  • Population: A group of individuals of the same species residing in the same area
  • Community: Interacting populations in the same area
  • Ecosystem: The community combined with its physical environment
  • Biosphere: All ecosystems combined
• Food chains and food webs:
  • Trophic levels are producers, consumers, and decomposers
  • Energy flows through ecosystems
• Ecological succession: Species structure changes in an ecological community over time
• Biogeochemical cycles:
  • These include the carbon, nitrogen, and water cycles
• Biodiversity means the variety of life in an ecosystem
• Conservation biology focuses on the conservation of biodiversity
• Pollution refers to introducing harmful substances into the environment
• Climate change means a long-term change in average weather patterns

Evolutionary Theory

• Evolutionary theory explains the diversity of life on Earth
• Key concepts:
  • Evolution refers to change in the heritable characteristics of biological populations over generations
  • Natural selection is the process by which organisms better adapt to their environment to survive and reproduce
  • Adaptation: Trait that enhances an organism's survival and reproduction in its environment
  • Speciation: The process by which new species arise
• Evidence for evolution:
  • Fossils provide evidence
  • Comparative anatomy is evidence
  • Embryology provides evidence
  • Molecular biology
• Mechanisms of evolution:
  • Mutation
  • Gene flow
  • Genetic drift
  • Natural selection
• Darwin's theory of evolution occurs by natural selection
• The modern synthesis of evolutionary theory exists

Human Anatomy

• Human anatomy focuses on the structure of the human body
• Organ systems:
  • Skeletal system: Supports the body and provides structure
  • Muscular system: Enables movement
  • Nervous system: Controls and coordinates body functions
    • Includes the brain, spinal cord, and nerves
  • Endocrine system: Regulates body functions through hormones
  • Cardiovascular system: Transports blood, oxygen, and nutrients
    • This includes the heart, and blood vessels
  • Respiratory system: Exchanges gases, like oxygen and carbon dioxide
    • This is done by the lungs
  • Digestive system: Breaks down food and absorbs nutrients
    • This includes the stomach, intestines, liver, and pancreas
  • Excretory system: Eliminates waste products
    • Includes the Kidneys and bladder
  • Reproductive system: Enables reproduction
  • Immune system: Protects the body from disease
• Anatomical terminology:
  • Includes terms like anterior, posterior, superior, inferior, medial, lateral, proximal, and distal
• Tissues:
  • Epithelial tissue
  • Connective tissue
  • Muscle tissue
  • Nervous tissue
• Bones, muscles, organs, and their function occur