Biology Study Notes: Modules 1–3 (Chapters 1–3)

Module 1: Introduction to Biology (Ch. 1)

  • What is a molecule?

    • The smallest particle of a substance, made of two or more atoms chemically bonded together.

  • What is a cell?

    • The smallest unit of life with key life-sustaining capabilities:

    • Metabolize: Convert nutrients into energy, stored primarily in the molecule ATP.

    • Grow and repair: New cells arise from existing ones via cell division (mitosis and meiosis); grows and replaces dead/damaged cells in multicellular organisms.

    • Reproduce: Cells can replicate to produce new generations.

    • Respond to stimuli: Cells sense and react to environmental changes.

    • Maintain homeostasis: Regulate internal environment to keep conditions stable.

  • What is a tissue?

    • A collection of similar cells that work together to perform a specific function or set of functions.

    • Epithelial tissue: Forms coverings/linings; absorption, secretion, protection.

    • Connective tissue: Diverse types (bone, cartilage, blood, tendons); provides support, connects structures, transports substances.

    • Nervous tissue: Neurons and glial cells; transmits electrical impulses to communicate information.

    • Muscular tissue: Specialized for contraction and movement.

  • What is perception?

    • Perception is our conscious interpretation of the world, created by the brain from nerve impulses delivered by sensory receptors.

  • Levels of organization (atoms to organism)

    • Atoms

    • Molecules

    • Organelles

    • Cells

    • Tissues

    • Organs

    • Organ systems

    • Organism

Module 1: The Level-by-Level Concepts (Page 2–2 recap)

  • Atom: The smallest unit of matter; can be part of living or non-living things.

    • Example: A single oxygen atom (OO).

  • Molecule: Two or more atoms held together by chemical bonds.

    • Example: Water molecule (H2OH_2O).

  • Organelle: Structure within a cell that performs specific functions.

    • Example: Mitochondrion (energy production).

  • Cell: The basic, fundamental unit of all living organisms.

    • Example: Nerve cell (neuron) or a muscle cell.

  • Tissue: Group of similar cells working together to perform a function.

    • Example: Muscle tissue (composed of muscle cells that contract).

  • Organ: Structure made of different tissue types functioning together.

    • Example: Stomach (muscle, epithelial, connective tissues).

  • Organ System: Group of organs that work together to perform major organismal functions.

    • Example: Digestive system (stomach, intestines, and other organs).

  • Organism: A complete, individual living being.

    • Example: Human, dog, or plant.

Module 1: Biochemistry (Ch. 2)

  • Major elements of the human body (approximate percentages):

    • Oxygen: O≈65%O \approx 65\% of body mass

    • Carbon: C≈18.5%C \approx 18.5\%

    • Hydrogen: H≈9.5%H \approx 9.5\%

    • Nitrogen: N≈3.3%N \approx 3.3\%

  • Atomic number

    • The atomic number shows the number of protons in an atom's nucleus.

  • Subatomic particles that make up atoms

    • Protons: positively charged, in the nucleus

    • Neutrons: neutral, in the nucleus

    • Electrons: negatively charged, orbit the nucleus in electron shells

  • Ion

    • An ion is an atom or molecule that carries an electric charge, resulting from gain or loss of electrons.

  • Distinguishing atom vs ion; positive ions vs negative ions

    • Atom: electrically neutral with equal numbers of protons and electrons.

    • Ion: electrically charged due to unequal numbers of protons and electrons.

    • Positive Ion (Cation): forms when a neutral atom loses one or more electrons; carries a net positive charge. Example: Na → Na⁺.

    • Negative Ion (Anion): forms when a neutral atom gains one or more electrons; carries a net negative charge. Example: F → F⁻.

  • Mineral sources

    • Minerals come from food.

  • Organic vs inorganic molecules

    • Organic molecules contain carbon (and typically hydrogen; may contain nitrogen).

    • Inorganic compounds generally do not contain carbon–hydrogen bonds.

  • Polymer and monomer

    • Monomer: a small, simple molecule that serves as a repeating building block.

    • Polymer: a large, complex molecule made of many monomers linked together via polymerization.

  • The four major types of biomolecules (organic molecules)

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic acids

  • Major characteristics of carbohydrates

    • Primary fuel: glucose; quick energy (simple sugars) and sustained energy (complex carbohydrates).

    • Structural/functional roles: fiber; plant rigidity via polysaccharides like cellulose.

    • Energy storage: stored as glycogen in liver and muscles.

    • Genetic material component: ribose, a five-carbon sugar, is a component of RNA.

    • Forms: monosaccharides, disaccharides, polysaccharides.

  • Primary fuel and energy storage details

    • Carbohydrates are the body's main energy source; glucose is the preferred fuel for cells and the brain.

    • Unused glucose is stored as glycogen in liver and muscles.

  • Structural roles and genetic material

    • Plant rigidity is provided by cellulose (polysaccharide).

    • Ribose sugar is part of RNA, which carries genetic information.

  • Major characteristics of lipids

    • Largely nonpolar and hydrophobic (insoluble in water).

  • Major characteristics of proteins and their building blocks/monomers

    • Proteins are made of amino acids (building blocks/monomers).

  • Essential vs. non-essential amino acids

    • Essential amino acids must be obtained from the diet because the human body cannot synthesize them.

    • Non-essential amino acids can be synthesized by the body.

  • Major characteristics of nucleic acids

    • Nucleic acids are organic polymers composed of nucleotides.

    • Elements: C, H, O, N, P.

    • DNA (deoxyribonucleic acid): resides in the nucleus; stores genetic information; contains individual genes.

    • RNA (ribonucleic acid): carries out orders given by DNA.

Module 2: Cells (Ch. 3)

  • Prokaryotic vs. Eukaryotic cells

    • Prokaryotic cell: simple, single-celled; lacks a membrane-bound nucleus and other membrane-bound organelles.

    • Eukaryotic cell: organized internal structure; two major types: animal cells and plant cells.

    • Key features of eukaryotes:

    • Nucleus: membrane-bound organelle storing DNA.

    • Membrane-bound organelles: specialized compartments for tasks like energy production (mitochondria) and protein modification (Golgi apparatus and endoplasmic reticulum).

    • Generally larger than prokaryotic cells.

  • Major types of eukaryotic cells

    • Animal cells

    • Characteristics: flexible; lack a rigid cell wall.

    • Key organelles: Lysosomes; Centrioles; Cytoskeleton.

    • Plant cells

    • Characteristics: rigid cell wall provides structural support.

    • Key organelles: Cell wall; Chloroplasts; Large central vacuole.

  • Organelles and functions (within eukaryotic cells)

    • Nucleus: control center; stores DNA; regulates cellular activities.

    • Ribosomes: protein synthesis factories (made of rRNA and proteins).

    • Endoplasmic reticulum (ER): manufacturing and packaging system.

    • Golgi complex/apparatus: modifies, sorts, and packages proteins and lipids synthesized in the ER.

    • Lysosomes: digestive enzymes; recycle cellular waste; autophagy and phagocytosis.

    • Peroxisomes: break down fatty acids; detoxify harmful substances (e.g., hydrogen peroxide to water and oxygen).

    • Mitochondria: powerhouses; generate ATP via cellular respiration.

    • Chloroplasts: sites of photosynthesis; present in plant cells.

    • Cytosol: the fluid component of the cytoplasm.

  • Plasma membrane structure and functions

    • Fluid mosaic model: phospholipid bilayer with embedded proteins.

    • Phospholipid bilayer: hydrophobic (water-fearing) tails inward; hydrophilic (water-loving) heads outward.

    • Proteins: transport, signaling, receptors.

    • Cholesterol: maintains membrane fluidity and shape.

    • Glycocalyx: carbohydrates attached to lipids/proteins; important for cell–cell recognition and adhesion.

  • Nucleus

    • Structure: a membrane-bound organelle that houses DNA.

    • Function: control center; regulates gene expression and cellular activities.

  • Ribosomes

    • Function: protein synthesis; translate mRNA into polypeptide chains.

  • Endoplasmic Reticulum (ER)

    • Function: manufacturing and packaging system for proteins (rough ER with ribosomes) and lipids (smooth ER).

  • Golgi complex

    • Function: modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

  • Lysosomes and peroxisomes

    • Lysosomes: digestive enzymes; break down cellular waste and debris; autophagy/phagocytosis.

    • Peroxisomes: break down fatty acids; detoxify harmful substances; convert hydrogen peroxide to water and oxygen.

  • Mitochondria

    • Function: generate ATP via cellular respiration; power cellular activities.

  • Chloroplast and its function

    • Function: photosynthesis in plant cells; convert light energy into chemical energy.

  • Cytosol

    • The fluid component of the cytoplasm; site of many metabolic processes.

  • Cytoskeleton (mentioned as part of animal cells)

    • Provides structural support and facilitates movement; not elaborated in detail in the transcript but noted in animal cells.

  • Plasma membrane details recap

    • Structure: fluid mosaic with a phospholipid bilayer, proteins, cholesterol, and glycocalyx for recognition and adhesion.

Module 3: Cellular respiration (Ch. 3; Module 3)

  • Overview

    • Cellular respiration is the metabolic process by which cells convert chemical energy from food molecules into adenosine triphosphate (ATP) to power cellular activities.

    • General equation (simplified):

    C<em>6H</em>12O<em>6+6O</em>2→6CO<em>2+6H</em>2O+ATP (energy)C<em>6H</em>{12}O<em>6 + 6O</em>2 \rightarrow 6CO<em>2 + 6H</em>2O + \text{ATP (energy)}

  • Glucose + Oxygen → Carbon Dioxide + Water + Energy

Module 3: Tissues (Ch. 3)

  • Definition of a tissue

    • A group of cells that share a similar structure and function as a unit.

  • Major characteristics of epithelial tissue (slide 5)

    • Simple epithelium: one cell layer thick; all cells touch the basement membrane; named by shape.

    • Stratified epithelium: more than one cell layer; some cells rest on top of others and do not touch the basement membrane; named by the shape of the topmost layer.

  • Major characteristics and types of connective tissue (slides 8–9)

    • Most diverse and abundant tissue in the body.

    • Characteristics:

    • Cells occupy less space than the extracellular matrix.

    • Varied vascularity: some tissues have many blood vessels; others (e.g., cartilage) have few or none.

    • Function: binds and connects organs.

    • Four types of connective tissue:

    • Fibrous connective tissue: most diverse; contains protein fibers (e.g., collagen, elastic).

    • Adipose tissue (fat tissue): adipocytes store fat and can enlarge.

    • Supportive connective tissue: cartilage (rubbery matrix) and bones (calcified matrix).

    • Fluid connective tissue: blood; transports oxygen, carbon dioxide, nutrients throughout the body.

  • Major characteristics of nervous tissue

    • Composed of neurons and glial cells.

  • Major characteristics of muscular tissue (slides 15; see slides 16–18 for organ locations)

    • Specialized to contract (shortening of the cell) when stimulated or excited; enables movement.

    • All body movements: digestion, waste elimination, breathing, circulation, speech, etc.

    • Some movements are voluntary and some are involuntary depending on the muscle type.

    • Three types of muscular tissue:

    • Skeletal muscle: long threadlike cells (muscle fibers); voluntary movements; striated; each cell has multiple nuclei near the membrane.

    • Cardiac muscle: found in the heart; (transcript notes it as a distinct type but does not give extra details beyond location here).

    • Smooth muscle: fusiform cells; involuntary; no striations; usually one nucleus per cell; forms layers in walls of blood vessels, digestive, respiratory, urinary tracts, uterus, etc.

  • Types of tissue repair and their differences (slide 19)

    • Regeneration: replacement by the same cell type; restores normal function; examples: most skin injuries, liver.

    • Fibrosis: replacement with scar tissue (mostly collagen) produced by tissue cells; maintains tissue integrity but does not restore normal function; examples: severe cuts/burns, muscle injuries, lungs in tuberculosis.

  • Atrophy

    • Decrease in size of tissue or organ; muscle wasting is a common example.

  • Infarction

    • Sudden death of tissue due to loss of blood supply (slide 20).

Module 3: Homeostasis (Ch. 3)

  • Definition and importance

    • Homeostasis: the maintenance of stable internal conditions in the body, essential for organismal survival.

  • Dysbiosis

    • Dysbiosis is an imbalance in the types or numbers of microbial communities that colonize a host organism, leading to departure from a healthy, balanced state called symbiosis.

  • The three essential elements for control systems (slides 11–13)

    • Detectors (receptors): detect deviations from a set point.

    • Control center: processes information and determines the appropriate response.

    • Effectors: carry out the response to return to homeostasis.

  • Organismal organization and organ recognition

    • You do not need to memorize all organs, but you should be able to distinguish organs.

    • Examples of organs include hair, pancreas, skin, blood vessels, brain, kidneys, etc.

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