General Biology Study Notes: Chemistry of Life, Cells, Organ Systems, Skeletal and Muscular Systems

Chapter 2: Chemistry of Life

General Chemistry

Understanding the chemical basis of life is essential for studying biology. All living things are composed of matter, which consists of elements and compounds.

• Matter: Anything that has mass and occupies space. Composed of elements. Radiation/light is not matter.

• Elements: Substances that cannot be broken down into simpler forms. Arranged in the periodic table. Of the 92 naturally occurring elements, 25 are essential to life.

• Atoms: Smallest unit that retains the properties of an element.

Chemical Bonds: Linking Atoms to Form Molecules

• Chemical bonds: Attractive forces holding atoms together.

• Types:

  • Covalent bonds: Atoms share electrons.

    • Nonpolar: Electrons shared equally (e.g., H2, O2).

    • Polar: Electrons not shared equally (e.g., H2O).

  • Ionic bonds: Attraction between oppositely charged ions.

    • Ion: Electrically charged atom or molecule.

    • Example: NaCl

  • Hydrogen bonds: Weak attraction between oppositely charged regions of polar molecules (e.g., water).

Compounds

• Substance consisting of two or more elements combined in a fixed ratio.

• Has characteristics different from those of its elements.

Key Properties of Water

Water is vital for life due to its unique properties.

• Excellent solvent

• Liquid at body temperature

• Can absorb and hold heat energy

• Evaporative cooling removes heat from organisms

• Participates in chemical reactions (e.g., dehydration synthesis, hydrolysis)

pH Scale

• Expresses hydrogen ion concentration.

• Acidic: pH < 7

• Neutral: pH = 7

• Basic: pH > 7

Organic Chemistry

• Carbon: Common building block of organic molecules. Forms four covalent bonds. Can form single or double bonds.

• Polar molecules: Uneven charges on the same molecule. Capable of hydrogen bonding.

Macromolecules of Life

• Carbohydrates: Energy, structure. General formula: CnH2nOn. Monosaccharides (single unit), disaccharides (two units), polysaccharides (many units).

• Lipids: Insoluble in water.

  • Triglycerides: Energy storage.

  • Phospholipids: Cell membrane structure.

  • Steroids: Carbon-based ring structures (e.g., cholesterol, hormones).

• Proteins: Building blocks of life. Made of amino acids joined by peptide bonds. Functions: enzymes, structure, transport, communication.

• Nucleic acids: DNA and RNA. Store and transmit genetic information.

Biochemistry

• Energy: Capacity to do work.

  • Potential energy: Stored energy.

  • Kinetic energy: Energy in motion.

  • Chemical energy: Can be transformed into kinetic energy.

• Enzymes: Biological catalysts that speed up chemical reactions.

  • Function depends on temperature, pH, ion concentration.

  • Denaturation: Loss of enzyme function due to extreme conditions.

• ATP: Universal energy source. Structure: adenosine triphosphate.

  • One glucose molecule may yield 36 ATPs.

Chapter 3: Structure and Function of Cells

Cell Doctrine

• All living things are composed of cells.

• A single cell is the smallest unit of life.

• All cells come from pre-existing cells.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells: Bacteria. No nucleus, no organelles, always have cell walls.

• Eukaryotic cells: All other organisms. Have nucleus and organelles.

Cell Size and Efficiency

• Small cells have higher surface-to-volume ratio, allowing efficient exchange of nutrients and waste.

Plasma Membrane

• Separates cell from environment. Selectively permeable.

• Lipid bilayer:

  • Phospholipids: Polar head, nonpolar tail.

  • Cholesterol: Adds rigidity.

  • Proteins: Transport, recognition.

  • Carbohydrates: Recognition patterns.

• Fluid mosaic model: Membrane is flexible and dynamic.

Transport Across Membrane

• Passive transport: No energy required.

  • Diffusion: Movement from high to low concentration.

  • Osmosis: Diffusion of water.

• Active transport: Requires energy.

  • Endocytosis: Substances enter cell.

  • Exocytosis: Substances exit cell.

Isotonic, Hypertonic, Hypotonic Solutions

Solution Type	Solute Concentration	Effect on Cell
Isotonic	Equal inside and outside	No net movement
Hypertonic	Higher outside	Cell shrinks
Hypotonic	Lower outside	Cell swells and may burst

Cell Organelles and Functions

• Nucleus: Contains genetic information, controls cell activities.

• Ribosomes: Site of protein synthesis.

• Endoplasmic Reticulum (ER): Manufacturing center.

  • Rough ER: Has ribosomes, protein synthesis.

  • Smooth ER: Lipid synthesis.

• Golgi Apparatus: Refines, packages, ships products.

• Lysosomes: Digest other cells, contain hydrolytic enzymes.

• Mitochondria: Site of cellular respiration, generates ATP.

• Cytoskeleton: Supports cell, enables movement.

• Cilia and Flagella: Specialized for movement.

Cell Metabolism and Energy

• Anabolism: Assembly of larger molecules from smaller ones (requires energy).

• Catabolism: Breakdown of larger molecules (releases energy).

• Glucose metabolism:

  • One glucose molecule may yield 36 ATP.

  • Cellular respiration: Glycolysis, citric acid cycle, electron transport chain.

Chapter 4: From Cells to Organ Systems

Types of Tissue

• Epithelial: Protection, secretion.

• Connective: Support, structure.

• Muscle: Movement.

• Nervous: Communication.

Epithelial Tissue

• Simple (one layer) or stratified (multiple layers).

• Shapes: Cuboidal, columnar, squamous.

• Lines body cavities, protects against injury.

• Glandular epithelium: Secretes chemicals.

Connective Tissue

• Supports organs, stores fat, produces blood cells.

• Matrix: Nonliving extracellular material.

• Fibrous connective tissue: Strength, elasticity.

• Specialized connective tissue: Cartilage, bone, blood.

Muscle Tissue

• Skeletal: Voluntary, multi-nucleated.

• Cardiac: Involuntary, single nucleus, heart only.

• Smooth: Involuntary, single nucleus, surrounds hollow structures.

Nervous Tissue

• Neurons: Transmit electrical impulses.

• Glial cells: Support and protect neurons.

Organs and Organ Systems

• Organs: Two or more tissue types joined for specific functions.

• Organ systems: Groups of organs with a common function.

Skin: Epidermis and Dermis

• Epidermis: Outer layer, stratified squamous epithelial cells.

• Dermis: Middle layer, supports tissues, contains fibroblasts, white blood cells, fat cells, hair follicles.

Hair and Nails

• Hair: Grows from follicles, color from melanin.

• Nails: Grows from keratinocytes.

Vitamin D Formation

• Starts in skin, complex series of reactions.

Disease Overview

• Germ theory: Microorganisms cause disease.

• Immune deficiencies: Cancer, allergies, genetics.

• Environmental toxins: Chemicals, poisons, gases.

• Skin disorders: Acne, cancer, hemangioma, melanoma, vitiligo, psoriasis, necrotizing fasciitis, shingles.

Chapter 5: The Skeletal System

Functions of the Skeleton

• Support, protection, movement, blood cell formation, mineral/fat storage.

Skeletal System Structure

• Bone: Hard elements, living cells.

• Ligaments: Attach bone to bone.

• Cartilage: Support under pressure.

Bone Development and Repair

• Osteoblasts: Build bone tissue.

• Osteoclasts: Break down bone tissue.

• Repair: Hematoma formation, fibrocartilage callus, bony callus, bone remodeling.

Types of Bones

• Long, short, flat, irregular.

Skeleton Organization

• Axial: Skull, sternum, ribs, vertebral column.

• Appendicular: Limbs, pelvic and pectoral girdles.

Diseases and Disorders

• Sprains, bursitis, tendinitis, arthritis, osteoporosis, bone cancer.

Chapter 6: The Muscular System

Functions of the Muscular System

• Mobility, protection, circulation, temperature regulation, transport of nutrients and fluids.

Muscle Types

• Skeletal: Voluntary, multi-nucleated.

• Cardiac: Involuntary, heart only.

• Smooth: Involuntary, surrounds hollow organs.

Muscle Structure

• Muscle cells grouped by origin, insertion, function.

• Fascicles: Bundles of muscle fibers.

• Muscle fibers: Cylindrical, contain actin and myosin.

Muscle Contraction

• Sarcomere: Smallest contractile unit. Contains thick (myosin) and thin (actin) filaments.

• Calcium initiates sliding filament mechanism.

• ATP required for contraction and relaxation.

Muscle Energy and Training

• Strength training: Increases muscle mass.

• Aerobic training: Increases blood supply, mitochondria, myoglobin.

Muscle Disorders

• Muscular dystrophy, tetanus, cramps, fascitis, tendonitis.

Major Muscles to Know

Muscle	Function
Pectoralis Major	Draws arm forward
Biceps Brachii	Bends forearm
Rectus Abdominis	Compresses abdomen
External Oblique	Compresses chest cavity
Sartorius	Bends thigh at hip
Quadriceps Femoris	Straightens leg at knee
Gastrocnemius	Bends lower leg at knee
Achilles Tendon	Connects gastrocnemius to heel

Additional info: These notes expand on the original bullet points with academic context, definitions, and examples for clarity and completeness.