Course

Biology

Khan Academy

This Biology course is designed to provide a comprehensive overview of essential concepts found in first-year college or high school biology. The curriculum encompasses:

  • Fundamentals of evolution and natural selection
  • Introduction to DNA and genetics
  • Cellular processes like mitosis and meiosis
  • Understanding respiration and photosynthesis
  • Immune system mechanisms and functions
  • Human anatomy and the circulatory system
  • Introduction to microorganisms like bacteria and viruses
  • Role of stem cells in development
  • Concepts of heredity and genetic traits
  • Applications of biological processes in medicine and health

By the end of the course, students will gain a solid foundation in biological sciences and the ability to apply this knowledge to real-world scenarios.

Course Lectures
  • This module introduces the key concepts of evolution, emphasizing the importance of variation within populations and the mechanisms of natural selection. Students will learn:

    • The theory of evolution and its historical context
    • How variation contributes to a population's adaptability
    • Case studies illustrating natural selection in action

    Understanding these principles lays the groundwork for further exploration of biological diversity and species development.

  • This module presents arguments for intelligent design in contrast to evolutionary theory. Students will critically evaluate:

    • The main tenets of evolutionary biology
    • Claims made by proponents of intelligent design
    • Scientific evidence supporting evolution

    The goal is to foster analytical thinking and an understanding of differing perspectives in biological science.

  • This module clarifies common misconceptions about evolution and intelligent design. It aims to:

    • Address frequently asked questions regarding both theories
    • Provide clear definitions and concepts
    • Encourage informed discussions on the topic

    Through this module, students will gain confidence in discussing evolutionary concepts and their implications.

  • This module focuses on the Owl Butterfly, illustrating how natural selection may have influenced its distinctive wing patterns. Students will explore:

    • The role of camouflage and mimicry in survival
    • Real-world examples of natural selection
    • How specific traits can confer advantages in the wild

    Understanding these concepts will help students appreciate the complexity of evolutionary adaptations.

  • DNA: Introduction
    Salman Khan

    This module provides an introduction to DNA, the molecule of life. Students will learn about:

    • The structure of DNA and its components
    • How DNA carries genetic information
    • The role of DNA in heredity and cell function

    By the end of this module, students will understand the fundamental importance of DNA in biology.

  • This module explores how variation can be introduced into a species through several mechanisms. Topics covered include:

    • Mutations and their effects on genetic diversity
    • Gene flow between populations
    • Sexual reproduction and its role in variation

    Students will appreciate the significance of genetic variation for evolution and adaptation.

  • This module delves into the vocabulary and structure of DNA, focusing on key terms such as:

    • Chromosomes
    • Chromatids
    • Chromatin
    • Transcription and translation processes
    • DNA replication

    Students will learn how these components work together to ensure the proper functioning of cells.

  • This module provides an overview of mitosis and meiosis, two critical processes in cell division and reproduction. Key topics include:

    • The phases of mitosis and their significance
    • Understanding meiosis and its role in sexual reproduction
    • Gametes, zygotes, and their genetic implications

    Students will gain insight into how these processes contribute to genetic continuity and variation.

  • Mitosis
    Salman Khan

    This module focuses on the phases of mitosis, detailing each step in the process of cell division. Students will learn about:

    • Prophase, metaphase, anaphase, and telophase
    • The role of spindle fibers in chromosome movement
    • How mitosis ensures equal distribution of genetic material

    Comprehending mitosis is essential for understanding cellular reproduction and growth.

  • Meiosis
    Salman Khan

    This module details meiosis, the specialized process of cell division that produces gametes. Key topics include:

    • The stages of meiosis I and meiosis II
    • How meiosis contributes to genetic diversity
    • The significance of crossing over and independent assortment

    Students will understand how meiosis is fundamental to sexual reproduction and genetic variation.

  • This module provides an overview of embryonic development, specifically from zygote to embryo. Topics covered include:

    • Stages of early development
    • Introduction to embryonic and somatic stem cells
    • The role of stem cells in growth and development

    Students will appreciate the complexity of development and the potential applications of stem cell research.

  • This module covers principles of heredity and classical genetics. Students will learn about:

    • Dominant and recessive traits
    • Heterozygous and homozygous genotypes
    • Basic Mendelian genetics

    Understanding these concepts is crucial for studying inheritance patterns and genetic variation.

  • This module introduces the Punnett Square, a tool for predicting genetic outcomes from dihybrid crosses. Topics include:

    • Independent assortment of alleles
    • Understanding incomplete dominance and codominance
    • Application of Punnett Squares in genetics

    Students will learn to analyze genetic crosses and interpret inheritance patterns effectively.

  • This module introduces the Hardy-Weinberg Equilibrium, a principle in population genetics. Students will learn about:

    • Conditions required for a population to be in Hardy-Weinberg Equilibrium
    • Calculating allele and genotype frequencies
    • Implications for evolution and population dynamics

    Understanding this equilibrium is essential for studying evolutionary processes in populations.

  • This module focuses on sex-linked traits and the chromosomal basis of gender. Key topics include:

    • The role of sex chromosomes in determining gender
    • Examples of sex-linked traits and their inheritance patterns
    • Implications for genetic disorders

    Understanding sex-linked traits is vital for grasping complex inheritance scenarios.

  • Bacteria Introduction
    Salman Khan

    This module introduces bacteria, exploring their characteristics, structure, and ecological roles. Topics include:

    • Types of bacteria and their classifications
    • Importance of bacteria in ecosystems
    • Interactions with humans and other organisms

    Students will appreciate the diversity and significance of bacteria in both health and disease.

  • Viruses Introduction
    Salman Khan

    This module provides an overview of viruses, their structure, and how they infect host cells. Students will learn about:

    • Differences between viruses and living organisms
    • Mechanisms of viral replication
    • Impact of viruses on health and disease

    Understanding viruses is essential for grasping their role in infectious diseases and public health.

  • This module introduces adenosine triphosphate (ATP), the energy currency of the cell. Key concepts include:

    • The structure of ATP and its role in metabolism
    • How ATP is generated and utilized by cells
    • Importance of ATP in cellular processes

    Students will understand how ATP facilitates energy transfer within biological systems.

  • Cellular Respiration
    Salman Khan

    This module covers the process of cellular respiration, detailing how cells convert glucose into energy. Key topics include:

    • The stages of cellular respiration: glycolysis, Krebs cycle, and electron transport chain
    • How energy is produced and utilized
    • Importance of respiration in maintaining cellular functions

    Understanding cellular respiration is crucial for comprehending how organisms harness energy from food.

  • This module provides an overview of oxidation and reduction reactions in biological contexts. Students will explore:

    • The principles of oxidation and reduction
    • Examples of these reactions in metabolic processes
    • The significance of redox reactions in energy transfer

    Understanding these concepts is essential for grasping how cells generate and utilize energy.

  • This module focuses on the role of oxidation and reduction in cellular respiration, reconciling biological and chemical definitions. Key topics include:

    • How these reactions facilitate energy production
    • The relationship between oxidation, reduction, and metabolic pathways
    • Examples of redox reactions in respiration

    Students will appreciate the interconnected nature of these processes in energy metabolism.

  • This module provides an overview of glycolysis, the first step in cellular respiration. Students will learn about:

    • The steps involved in glycolysis
    • The energy yield from glycolysis
    • How glycolysis fits into the overall process of cellular respiration

    Understanding glycolysis is crucial for comprehending how cells extract energy from glucose.

  • This module covers the Krebs cycle, also known as the citric acid cycle. Key concepts include:

    • The series of reactions that occur in the mitochondria
    • The production of energy carriers such as NADH and FADH2
    • Importance of the Krebs cycle in cellular respiration

    Students will understand how the Krebs cycle integrates with other metabolic pathways.

  • This module provides an overview of the electron transport chain, a critical component of cellular respiration. Key topics include:

    • The components of the electron transport chain
    • How electrons are transferred and energy is produced
    • The role of oxygen in the process

    Understanding the electron transport chain is essential for grasping how cells generate ATP efficiently.

  • This module focuses on oxidative phosphorylation and chemiosmosis, detailing how ATP is generated in mitochondria. Students will learn:

    • How proton gradients are established and utilized
    • The role of ATP synthase in ATP production
    • Corrections to previous concepts regarding energy production

    Understanding these processes is vital for comprehending cellular energy metabolism.

  • Photosynthesis
    Salman Khan

    This module provides an overview of photosynthesis, the process by which plants convert light energy into chemical energy. Key topics include:

    • The overall equation for photosynthesis
    • Importance of chlorophyll and light absorption
    • How photosynthesis supports life on Earth

    Understanding photosynthesis is essential for grasping the foundations of energy flow in ecosystems.

  • This module delves into the details of the light-dependent reactions of photosynthesis. Students will learn about:

    • The role of sunlight in energizing electrons
    • The production of ATP and NADPH
    • How these reactions set the stage for the Calvin Cycle

    Understanding these processes is critical for appreciating how plants harness solar energy.

  • This module covers the Calvin Cycle, also known as the light-independent reactions of photosynthesis. Key topics include:

    • The process of carbon fixation
    • How ATP and NADPH produced in the light reactions are utilized
    • The importance of the Calvin Cycle in plant metabolism

    Students will appreciate how the Calvin Cycle integrates with the light-dependent reactions to complete photosynthesis.

  • This module continues the discussion on the Calvin Cycle, focusing on photorespiration and its implications. Key topics include:

    • The process of photorespiration
    • How it affects plant efficiency
    • Strategies plants use to minimize photorespiration

    Students will learn how photorespiration influences plant growth and productivity.

  • This module introduces C-4 photosynthesis, a process some plants use to minimize photorespiration. Key topics include:

    • The mechanisms of C-4 photosynthesis
    • Examples of C-4 plants
    • Advantages of this adaptation in certain environments

    Students will understand how C-4 photosynthesis allows plants to thrive in hot and dry conditions.

  • CAM Plants
    Salman Khan

    This module explores CAM plants, which have adapted to fix carbon at night to reduce water loss. Topics include:

    • The differences between CAM and C-4 photosynthesis
    • Examples of CAM plants
    • How these adaptations help conserve water

    Students will appreciate the diversity of plant adaptations to environmental challenges.

  • Cell Parts
    Salman Khan

    This module focuses on the structure and function of cell parts. Students will learn about:

    • Components of a typical eukaryotic cell
    • The functions of organelles such as the nucleus, mitochondria, and chloroplasts
    • How these structures work together to maintain cellular function

    Understanding cell structures is fundamental to the study of biology.

  • Diffusion and Osmosis
    Salman Khan

    This module covers the principles of diffusion and osmosis, two essential processes in cellular function. Students will explore:

    • The differences between diffusion and osmosis
    • Factors affecting the rate of diffusion
    • How these processes impact cell functionality

    Understanding diffusion and osmosis is crucial for grasping how substances move in and out of cells.

  • This module introduces the pulmonary system, including the anatomy and function of the lungs. Key topics include:

    • The structure of the larynx, trachea, bronchi, and alveoli
    • The mechanics of breathing and gas exchange
    • How the pulmonary system supports overall health

    Students will gain a solid understanding of respiratory anatomy and physiology.

  • This module focuses on the role of red blood cells in oxygen uptake by hemoglobin. Key concepts include:

    • The structure and function of hemoglobin
    • Mechanisms of oxygen transport in the bloodstream
    • Factors affecting oxygen binding and release

    Students will understand how red blood cells contribute to respiration and overall physiology.

  • This module provides an introduction to the circulatory system and the heart's anatomy. Key topics include:

    • The structure of the heart and its chambers
    • The blood flow pathway through the circulatory system
    • The role of the heart in maintaining homeostasis

    Students will gain a foundational understanding of cardiovascular physiology.

  • Hemoglobin
    Salman Khan

    This module focuses on hemoglobin and its role in the circulatory system. Students will learn about:

    • The composition and function of hemoglobin
    • How hemoglobin interacts with oxygen and carbon dioxide
    • Implications for respiratory health

    Understanding hemoglobin's function is essential for grasping respiratory physiology.

  • Neuron: Anatomy
    Salman Khan

    This module introduces the neuron and its anatomical features. Key aspects include:

    • The structure of neurons, including dendrites and axons
    • Types of neurons and their functions
    • The importance of neurons in nervous system communication

    Students will appreciate the complexity of neuronal structure and its relevance to physiology.

  • Sodium Potassium Pump
    Salman Khan

    This module focuses on the sodium-potassium pump, a crucial mechanism for maintaining membrane potential. Key topics include:

    • How the sodium-potassium pump works
    • The significance of maintaining a voltage gradient
    • Role of the pump in nerve impulse transmission

    Understanding this pump is essential for grasping cellular excitability and function.

  • This module discusses electronic and action potentials, particularly in neurons. Key concepts include:

    • The generation and propagation of action potentials
    • How these potentials affect neuronal communication
    • Corrections to previous understandings of these processes

    Students will learn how action potentials are fundamental to nervous system function.

  • This module focuses on saltatory conduction in neurons, a mechanism that enhances signal transmission. Topics covered include:

    • The role of myelin sheath in speeding up conduction
    • How action potentials propagate along myelinated axons
    • Implications for nervous system efficiency

    Students will appreciate how saltatory conduction optimizes neuronal communication.

  • This module discusses neuronal synapsis, focusing on chemical signaling between neurons. Key concepts include:

    • The mechanisms of neurotransmitter release and receptor binding
    • How synaptic transmission influences neuronal communication
    • Role of synapses in overall neural networks

    Understanding synaptic communication is crucial for grasping how neurons interact within the nervous system.

  • Myosin and Actin
    Salman Khan

    This module introduces myosin and actin, critical proteins involved in muscle contraction. Key topics include:

    • The structure and function of myosin and actin filaments
    • How these proteins interact to produce mechanical force
    • The role of myosin and actin in muscle physiology

    Students will understand the molecular basis of muscle movement.

  • This module focuses on tropomyosin and troponin, proteins that regulate muscle contraction. Key concepts include:

    • How tropomyosin and troponin interact with actin and myosin
    • The role of calcium ions in muscle contraction regulation
    • Implications for muscle physiology and movement

    Students will appreciate the complexity of muscle contraction regulation.

  • This module covers the role of the sarcoplasmic reticulum in muscle cells, particularly in calcium homeostasis. Key topics include:

    • Structure and function of the sarcoplasmic reticulum
    • How it regulates calcium ion concentrations
    • The importance of calcium in muscle contraction

    Students will understand how the sarcoplasmic reticulum contributes to muscle physiology.

  • Muscle Cell Structure
    Salman Khan

    This module provides an overview of muscle cell structure, focusing on the components that facilitate contraction. Key aspects include:

    • Arrangement of actin and myosin filaments
    • Role of other organelles in muscle function
    • The overall architecture of muscle fibers

    Students will appreciate how muscle cell structure supports its function.

  • This module discusses the role of phagocytes in innate immunity, including their types and functions. Key topics include:

    • The function of neutrophils, macrophages, and dendritic cells
    • How phagocytes identify and engulf pathogens
    • The role of MHC II in immune responses

    Students will understand the importance of phagocytes in the immune system's first line of defense.

  • This module provides an overview of innate and adaptive immune responses, highlighting their differences and interactions. Key topics include:

    • The components of innate immunity versus adaptive immunity
    • The roles of humoral and cell-mediated responses
    • How these systems work together to protect the body

    Students will gain insight into the complexity of the immune system.

  • This module focuses on B cells (B lymphocytes) and their activation processes. Students will learn about:

    • The role of B cells in the adaptive immune response
    • How B cells produce antibodies
    • The importance of B cell activation for effective immunity

    Understanding B cell function is crucial for grasping humoral immunity.

  • This module discusses professional antigen-presenting cells (APCs) and their role in activating T cells. Key concepts include:

    • The function of MHC II complexes
    • How APCs present antigens to T cells
    • The significance of this interaction in adaptive immunity

    Students will understand how APCs facilitate immune responses and T cell activation.

  • This module focuses on helper T cells and their role in activating B cells. Key topics include:

    • The mechanisms through which helper T cells stimulate B cells
    • The importance of this activation for antibody production
    • How helper T cells coordinate immune responses

    Students will appreciate the critical role of helper T cells in the adaptive immune system.

  • This module discusses cytotoxic T cells and how they are activated by MHC-I/antigen complexes. Key concepts include:

    • The role of cytotoxic T cells in targeting infected cells
    • How MHC-I presents antigens for recognition
    • The importance of this activation for cellular immunity

    Understanding cytotoxic T cell function is vital for comprehending how the body defends against infections.

  • This module provides a review of B cells, CD4+ T cells, and CD8+ T cells, summarizing their roles in the immune system. Key topics include:

    • The distinct functions of B cells and T cells
    • How these cells interact to mount effective immune responses
    • The importance of memory cells in long-term immunity

    Students will gain a comprehensive understanding of the adaptive immune system.

  • Inflammatory Response
    Salman Khan

    This module covers the inflammatory response, detailing the body's reaction to injury or infection. Key topics include:

    • The stages of inflammation
    • Cells involved in the inflammatory process
    • The significance of inflammation in immunity

    Students will understand how the inflammatory response protects the body and facilitates healing.

  • Kidney Function
    Salman Khan

    This module provides an overview of kidney function, focusing on how nephrons filter blood. Key concepts include:

    • The structure and function of nephrons
    • Processes of filtration and reabsorption
    • The role of kidneys in maintaining homeostasis

    Students will gain insight into how kidneys contribute to overall health and fluid balance.

  • This module covers secondary active transport in the nephron, detailing how substances are reabsorbed. Key topics include:

    • The mechanisms of secondary active transport
    • How it contributes to nutrient and ion reabsorption
    • The importance of this process in kidney function

    Students will appreciate the complexity of kidney transport mechanisms.

  • This module introduces cancer as a consequence of broken DNA replication. Key topics include:

    • How errors in DNA replication can lead to cancer
    • The role of mutations in cancer development
    • Implications for prevention and treatment

    Students will understand the molecular basis of cancer and its impact on health.