Seeley’s Essentials of Anatomy & Physiology - Chapter 3: Cell Structures and Their Functions

Comprehensive vocabulary flashcards covering cell structure, membrane transport, organelles, gene expression, and the cell cycle as described in Seeley’s Essentials of Anatomy & Physiology Tenth Edition, Chapter 3.

Organelles

Specialized structures in cells that perform specific functions, such as the nucleus, mitochondria, and ribosomes.

Cytoplasm

A jelly-like substance located within the cell that holds organelles.

Cell membrane

Also termed the plasma membrane, this structure encloses the cytoplasm and forms a boundary between intracellular and extracellular materials.

Intracellular

Refers to materials located inside the cell.

Extracellular

Refers to materials located outside the cell.

Fluid-mosaic model

The model used to describe the cell membrane structure, which contains phospholipids, cholesterol, proteins, and carbohydrates.

Phospholipid bilayer

A double layer of phospholipids consisting of polar (hydrophilic) heads exposed to water and nonpolar (hydrophobic) tails facing the membrane interior.

Selective permeability

A property of the cell membrane that allows only certain substances to pass in and out of the cell.

Passive membrane transport

Movement through the cell membrane that does not require the cell to expend energy.

Active membrane transport

Movement through the cell membrane that requires the cell to expend energy, usually in the form of ATP.

Diffusion

The movement of solutes in a solution from an area of higher concentration to an area of lower concentration down a concentration gradient.

Concentration gradient

The difference in the concentration of a solute in a solvent between two points divided by the distance between those two points.

Leak channels

Cell membrane channels that constantly allow ions to pass through.

Gated channels

Cell membrane channels that open and close to limit the movement of ions across the membrane.

Osmosis

The diffusion of water (a solvent) across a selectively permeable membrane from a region of higher water concentration to one of lower water concentration.

Osmotic pressure

The force required to prevent the movement of water across a cell membrane.

Hypotonic solution

A solution with a lower concentration of solutes and a higher concentration of water than the cell cytoplasm, causing water to move into the cell.

Lysis

The process where a cell swells enough to rupture, often occurring in a hypotonic solution.

Isotonic solution

A solution where solute concentrations are equal inside and outside the cell, resulting in no shrinking or swelling.

Hypertonic solution

A solution with a higher solute concentration and lower water concentration than the cell cytoplasm, causing water to move out of the cell.

Crenation

The shrinkage of a cell that occurs when it is placed in a hypertonic solution.

Facilitated diffusion

A carrier-mediated transport process that moves substances from higher to lower concentration without utilizing metabolic energy (ATP).

Active transport

A carrier-mediated process requiring ATP that moves substances against a concentration gradient from lower to higher concentration.

Sodium-potassium pump

A major active transport mechanism that moves $Na^+$ out of cells and $K^+$ into cells using energy from ATP breakdown.

Secondary active transport

A process that uses the energy from a concentration gradient established by the active transport of one substance, such as $Na^+$, to transport other substances.

Cotransport

A type of secondary active transport where the diffusing substance moves in the same direction as the initial active transported substance.

Countertransport

A type of secondary active transport where the diffusing substance moves in the opposite direction of the initial active transported substance.

Endocytosis

A process that brings materials into the cell using vesicles; includes receptor-mediated endocytosis, phagocytosis (solid particles), and pinocytosis (liquid particles).

Exocytosis

The process of releasing material from the cell using membrane-bound secretory vesicles that fuse with the cell membrane.

Nuclear envelope

A boundary consisting of outer and inner membranes with nuclear pores that surrounds the nucleus.

Chromatin

The loosely coiled form of chromosomes, consisting of DNA and proteins, found during most of a cell's life.

Nucleoli

Diffuse bodies within the nucleus that lack a surrounding membrane and are the site where ribosome subunits are formed.

Ribosomes

Organelles where proteins are produced; they can be free in the cytoplasm or attached to the endoplasmic reticulum.

Rough endoplasmic reticulum (ER)

A series of membranes with attached ribosomes involved in protein synthesis.

Smooth endoplasmic reticulum (ER)

A membrane system without ribosomes that is the site for lipid synthesis, cellular detoxification, and calcium ion storage in skeletal muscle.

Golgi apparatus

Closely packed stacks of membrane-bound sacs that collect, modify, package, and distribute proteins and lipids manufactured by the ER.

Lysosomes

Membrane-bound vesicles formed from the Golgi apparatus containing enzymes that function as intracellular digestive systems.

Peroxisomes

Membrane-bound vesicles containing enzymes that break down fatty acids, amino acids, and hydrogen peroxide ($H_2O_2$).

Mitochondria

Organelles responsible for producing ATP via aerobic metabolism; they feature an inner membrane with folds called cristae.

Cytoskeleton

The internal framework of the cell consisting of microtubules, microfilaments, and intermediate filaments.

Microtubules

Hollow protein structures that support the cytoplasm, assist in cell division, and form components of cilia and flagella.

Microfilaments

Small fibrils that structurally support the cytoplasm, determine cell shape, and enable movement or contraction in muscle cells.

Intermediate filaments

Protein fibrils that provide mechanical support to the cell; keratin in skin cells is a specific example.

Centrioles

Small, cylindrical organelles made of microtubules found in the centrosome and involved in the process of mitosis.

Cilia

Cylindrical structures extending from the cell surface composed of microtubules, responsible for moving materials like mucus.

Flagella

Long surface projections, usually occurring one per cell, that propel cells such as sperm.

Microvilli

Extensions of the cell membrane supported by microfilaments that increase surface area for absorption in areas like the intestine.

Gene expression

The process by which information in DNA directs protein synthesis through transcription and translation.

Transcription

The process occurring in the nucleus where a DNA segment is used as a template to form messenger RNA (mRNA).

Translation

The process in the cytoplasm where mRNA attaches to a ribosome and is read to produce a protein (polypeptide chain).

Gene

A sequence of nucleotides that provides a chemical set of instructions for making a specific protein.

Codon

A set of three nucleotide bases on mRNA that is read by an anticodon on tRNA during translation.

Interphase

The nondividing phase of the cell cycle where the cell performs normal functions and DNA replication occurs.

Mitosis

The cell dividing phase involving four stages: prophase, metaphase, anaphase, and telophase.

Prophase

The first phase of mitosis where chromatin condenses into chromosomes, spindle fibers form, and the nuclear membrane dissolves.

Metaphase

The second phase of mitosis where chromosomes align near the center of the cell.

Anaphase

The third phase of mitosis where chromatids separate into chromosomes and move toward opposite poles as the cytoplasm begins to divide.

Telophase

The final phase of mitosis where chromosomes organize into two separate nuclei and cytoplasm division is completed.

Differentiation

The process by which cells develop specialized structures and functions through the activation or inactivation of specific DNA portions.

Apoptosis

Programmed cell death, a normal process used to control cell numbers or remove extra tissue during development.

Metastasis

The process by which malignant tumors (cancer) spread to other parts of the body.