III Glossary

Active transport: Movement of molecules across the membrane requiring energy (ATP) to move substances against their concentration gradient (low to high concentration). (Chapter 3.3)

Amphipathic: Has both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions. (Chapter 3.2)

Anaphase: The stage of mitosis where sister chromatids are pulled apart to opposite sides of the cell, ensuring each daughter cell gets a full set of chromosomes. (Chapter 3.5)

Apoptosis: Programmed cell death; a controlled process that allows the body to eliminate damaged or unnecessary cells, often during development or in response to DNA damage. (Chapter 3.5)

Benign: Refers to a tumor or growth that is non-cancerous, non-invasive, and does not spread to other parts of the body. Benign tumors typically have a favorable prognosis. (Chapter 3.5)

Carrier proteins: Proteins that change their shape to move substances across the cell membrane. (Chapter 3.2)

Cell cycle: The series of stages through which a cell goes to prepare for division, involving growth, DNA replication, and cell division. It includes interphase, mitosis, and cytokinesis. (Chapter 3.5)

Cell membrane: Also called the plasma membrane; a selectively permeable structure that surrounds the cell, providing protection and regulating the movement of substances in and out. (Chapter 3.2)

Cell recognition proteins: Proteins that mark a cell’s identity so that it can be recognized by other cells. (Chapter 3.2)

Centromere: The region where two sister chromatids are joined together. (Chapter 3.5)

Centrosomes: Regions near the nucleus that contain centrioles, involved in the organization of the microtubules and spindle formation during cell division. (Chapter 3.4)

Channel proteins: Proteins that selectively allow materials, such as certain ions, to pass into or out of the cell. (Chapter 3.2)

Checkpoint: Control points in the cell cycle where the cell ensures that it is ready to proceed with DNA replication or cell division. If errors are detected, the cell cycle may be halted. (Chapter 3.5)

Chromatid: One of the two identical halves of a chromosome after DNA replication. (Chapter 3.5)

Chromatin: A complex of DNA and proteins (histones) found in the nucleus, which condenses into chromosomes during cell division. (Chapter 3.4, Chapter 3.5)

Cilia: Short, hair-like projections from the cell surface that are involved in movement of the cell or the movement of substances along the cell surface. (Chapter 3.4)

Cleavage furrow: A groove that forms in the cell membrane during cytokinesis in animal cells, helping to divide the cell into two daughter cells. (Chapter 3.5)

Concentration gradient: A difference in the concentration of a substance across a space or membrane, driving diffusion and osmosis. (Chapter 3.3)

Cytokinesis: The final step of cell division, where the cytoplasm divides and two distinct daughter cells are formed. (Chapter 3.5)

Cytoplasm: The gel-like substance inside the cell membrane, excluding the nucleus, that contains organelles and the cytosol, where most cellular processes occur. (Chapter 3.4)

Cytoskeleton: A network of protein fibers that provides structural support, facilitates cell movement, and plays a role in intracellular transport and cell division. (Chapter 3.4)

Cytosol: The gel-like fluid inside a cell where organelles, proteins, and molecules are suspended. (Chapter 3.2, Chapter 3.4)

Diffusion: The passive movement of molecules from an area of higher concentration to lower concentration until equilibrium is reached. (Chapter 3.3)

Diploid: A cell that contains two full sets of chromosomes (2n), one set from each parent. (Chapter 3.5)

Dual receptor proteins: A membrane receptor that can bind to two different ligands or perform two distinct functions within a signaling pathway. (Chapter 3.2)

Endocytosis: A process where the cell engulfs substances by forming a vesicle, allowing the intake of large molecules. (Chapter 3.3)

Endoplasmic reticulum (ER): An extensive network of membranes involved in protein and lipid synthesis. It comes in two forms: smooth and rough. (Chapter 3.4)

Eukaryotic cells: Cells that contain a nucleus and other membrane-bound organelles, such as mitochondria and the endoplasmic reticulum. (Chapter 3.4)

Exocytosis: A process where vesicles fuse with the plasma membrane to release substances outside the cell, used for removing waste or secreting proteins. (Chapter 3.3)

Extracellular fluid: Watery environments outside of the cell. (Chapter 3.2)

Extracellularly: Outside the cell. (Chapter 3.2)

Facilitated diffusion: A type of passive transport where molecules (e.g., glucose, ions) move across the membrane with the help of carrier or channel proteins. (Chapter 3.3)

Flagella: Long, whip-like structures that enable the cell to move. (Chapter 3.4)

Germ (or sex) cells: Reproductive cells (e.g., sperm and eggs) that carry half the genetic information (haploid) and combine during fertilization to form a zygote. (Chapter 3.5)

Glucose: A simple sugar that serves as the primary energy source for cells, used in cellular respiration to produce ATP. (Chapter 3.3)

Glucose transporter: A membrane protein that facilitates the movement of glucose into the cell through facilitated diffusion or active transport. (Chapter 3.3)

Glycoproteins: Proteins that have carbohydrate molecules attached that extend outside of the cell. (Chapter 3.2)

Golgi apparatus: A stack of membranous sacs involved in the modification, sorting, and packaging of proteins and lipids for secretion or delivery to other organelles. (Chapter 3.4)

Growth 1 phase (G1 phase): The first phase of interphase, where the cell grows, synthesizes proteins, and prepares for DNA replication. (Chapter 3.5)

Growth 2 phase (G2 phase): The final phase of interphase, where the cell continues to grow and prepares for mitosis by synthesizing proteins necessary for cell division. (Chapter 3.5)

Homologous: Refers to chromosomes that are similar in structure, size, and genetic content, one inherited from each parent. (Chapter 3.5)

Hydrophilic: Molecules or substances that are attracted to water and can dissolve or interact with it easily. (Chapter 3.2)

Hydrophobic: Molecules or substances that repel water and do not dissolve in it. (Chapter 3.2)

Hypertonic: A solution with a higher solute concentration outside the cell, causing water to move out of the cell, leading to cell shrinkage (crenation in animal cells). (Chapter 3.3)

Hypotonic: A solution with a lower solute concentration outside the cell, causing water to move into the cell, which may lead to cell swelling or bursting (lysis in animal cells). (Chapter 3.3)

Integral proteins: Proteins that are embedded in the membrane. (Chapter 3.2)

Intercellular fluid: The fluid found inside cells, making up about two thirds of the total body water; also called cytosol. (Chapter 3.2)

Intermediate filaments: Protein fibers that provide structural support and mechanical strength to the cell, helping to maintain its shape and resist stress. (Chapter 3.4)

Interphase: The phase of the cell cycle where the cell grows, replicates DNA, and prepares for mitosis. (Chapter 3.5)

Ion channel proteins: Membrane proteins that form pores in the cell membrane, allowing specific ions (e.g., Na⁺, K⁺, Ca²⁺, Cl⁻) to pass through. (Chapter 3.2)

Ions: Charged particles (positively or negatively) that are essential for cellular processes, such as nerve signaling and muscle contraction (e.g., Na⁺, K⁺, Ca²⁺, Cl⁻). (Chapter 3.3)

Isotonic: A solution in which the concentration of solutes is equal inside and outside the cell, resulting in no net movement of water across the membrane. (Chapter 3.3)

Ligand: A molecule that binds to a receptor protein to initiate a biological response. (Chapter 3.2)

Lysing: The rupturing of a cell due to excessive water intake in a hypotonic environment. (Chapter 3.3)

Lysosome: An organelle containing digestive enzymes that break down waste, cellular debris, and foreign substances. (Chapter 3.4)

Malignant: Refers to a tumor or growth that is cancerous, capable of invading surrounding tissues and spreading to other parts of the body (a process known as metastasis). (Chapter 3.5)

Metaphase: The stage of mitosis where chromosomes align in the middle of the cell along the metaphase plate. (Chapter 3.5)

Metastasized: Refers to the process by which cancer cells spread from their original (primary) site to other parts of the body, forming secondary tumors. (Chapter 3.5)

Microfilaments: Thin protein fibers that help support the cell shape and assist with movement. (Chapter 3.4)

Microtubules: Hollow protein structures that form part of the cytoskeleton and are involved in intracellular transport and cell division. (Chapter 3.4)

Mitochondria: Organelles known as the powerhouse of the cell, responsible for ATP production through cellular respiration. (Chapter 3.4)

Mitosis: A process of cell division in which a single cell divides to produce two identical daughter cells, maintaining the same chromosome number as the original cell. (Chapter 3.5)

Mitosis phrase: The phase of the cell cycle in which the nucleus divides into two identical nuclei, each containing the same number of chromosomes. (Chapter 3.5)

Nuclear envelope: A double membrane surrounding the nucleus, containing nuclear pores that regulate the passage of materials between the nucleus and cytoplasm. (Chapter 3.4)

Nuclear membrane: The double-layered membrane that surrounds the nucleus, separating the nuclear contents from the cytoplasm. (Chapter 3.4)

Nuclear pores: Protein complexes embedded in the nuclear envelope that regulate the transport of molecules (such as RNA and proteins) between the nucleus and cytoplasm. (Chapter 3.4)

Nucleolus: A dense structure within the nucleus responsible for ribosome production. (Chapter 3.4)

Nucleus: The control center of the cell, containing genetic material (DNA) and regulating cell activities. (Chapter 3.4)

Nutrients: Substances needed for cell survival and function, including carbohydrates, proteins, fats, vitamins, and minerals. (Chapter 3.3)

Organelles: Specialized structures within a cell that perform specific functions (e.g., mitochondria, Golgi apparatus, lysosomes). (Chapter 3.4)

Osmosis: The passive movement of water molecules across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration. (Chapter 3.3)

Passive transport: The movement of substances across the cell membrane without requiring energy, including diffusion, facilitated diffusion, and osmosis. (Chapter 3.3)

Peripheral proteins: Proteins that are attached to the surface of the cell membrane and participate in cell signaling and structural support. (Chapter 3.2)

Peroxisome: Membrane-bound organelles that contain enzymes for the breakdown of fatty acids and the detoxification of hydrogen peroxide. (Chapter 3.4)

Phagocytosis: A type of endocytosis where the cell engulfs large particles or microorganisms, forming a vesicle that fuses with a lysosome for digestion. (Chapter 3.3)

Phospholipid: A molecule with a hydrophilic head and two hydrophobic tails that makes up the cell membrane. (Chapter 3.2)

Pinocytosis: A type of endocytosis where the cell engulfs extracellular fluid and dissolved substances into small vesicles. (Chapter 3.3)

Plasma membrane: Another term for the cell membrane; a selectively permeable barrier that controls the movement of substances in and out of the cell. (Chapter 3.2)

Prophase: The first stage of mitosis where chromatin condenses into chromosomes, the nuclear envelope breaks down, and spindle fibers begin to form. (Chapter 3.5)

Receptor: Proteins in the cell membrane that bind to specific molecules (ligands) to trigger a cellular response. (Chapter 3.2)

Receptor-mediated endocytosis: A specialized form of endocytosis where specific molecules bind to cell-surface receptors, triggering vesicle formation to bring them inside. (Chapter 3.3)

Replicates: The process of duplicating a molecule, cell, or organelle to create an exact replica. (Chapter 3.5)

Ribosomes: Small organelles that synthesize proteins by translating messenger RNA (mRNA). (Chapter 3.4)

Rough endoplasmic reticulum (RER): A type of endoplasmic reticulum covered with ribosomes, responsible for protein synthesis and modification. (Chapter 3.4)

Selective permeability: The ability of the cell membrane to regulate which substances can enter or exit the cell. (Chapter 3.3)

Semipermeable: A property of the cell membrane that allows certain molecules to pass through while restricting others, maintaining internal balance; also known as selectively permeable. (Chapter 3.3)

Simple diffusion: The movement of small, nonpolar molecules across the membrane from a higher to a lower concentration without the help of membrane proteins. (Chapter 3.3)

Smooth endoplasmic reticulum: The part of the ER lacking ribosomes, involved in lipid synthesis, detoxification, and calcium storage. (Chapter 3.4)

Sodium-potassium pump: A transport protein that actively moves sodium ions out of the cell and potassium ions into the cell, maintaining cellular ion balance. (Chapter 3.3)

Somatic cell: Any cell that is not involved in reproduction, containing a full set of chromosomes (diploid, 2n). Examples include skin cells, muscle cells, and liver cells. (Chapter 3.5)

Spindle fibers: Microtubules that form during mitosis and help separate chromosomes. (Chapter 3.5)

Synthesis phrase (S phase): The phase of interphase where the cell replicates its DNA, ensuring each daughter cell receives an identical set of chromosomes. (Chapter 3.5)

Telophase: The final stage of mitosis where chromosomes reach opposite ends of the cell, the nuclear envelope reforms, and the chromosomes decondense into chromatin. (Chapter 3.5)

Vesicle: A small, membrane-bound sac that transports substances within or outside the cell. (Chapter 3.3)

Wastes: Unwanted byproducts of cellular metabolism that must be removed to maintain homeostasis, such as carbon dioxide (CO₂) and urea. (Chapter 3.3)