Cells and Their Functions – Vocabulary Flashcards

A comprehensive set of vocabulary flashcards covering major terms from the lecture on cell structure, membrane transport, genetics, cell division, and cancer.

Cell

The basic unit of life that exhibits organization, metabolism, responsiveness, homeostasis, growth, reproduction, and movement.

Cytology

The scientific study of cells.

Compound Light Microscope

A microscope that uses visible light and multiple lenses to magnify small specimens; common tool for studying cells.

Transmission Electron Microscope (TEM)

Microscope that passes electrons through thin specimens to reveal detailed internal cell structures.

Scanning Electron Microscope (SEM)

Microscope that bounces electrons off a specimen’s surface to produce three-dimensional images.

Plasma Membrane

The phospholipid bilayer enclosing cell contents and regulating what enters or leaves the cell.

Phospholipid Bilayer

Two layers of phospholipids forming the basic structure of the plasma membrane.

Cytoplasm

All cellular material between the nuclear membrane and the plasma membrane.

Cytosol

The fluid portion of cytoplasm containing water, enzymes, and nutrients.

Organelle

A specialized structure within a cell that performs a specific function.

Nucleus

Largest organelle; houses DNA and is surrounded by a nuclear membrane.

Chromosome

DNA-protein structure that carries genes governing cellular activities.

Nucleolus

Dark body within the nucleus that assembles ribosomal subunits.

Microvilli

Short plasma-membrane extensions that increase surface area for absorption.

Ribosome

Organelle composed of rRNA and protein; site of protein synthesis.

Rough Endoplasmic Reticulum (Rough ER)

Network of membranes studded with ribosomes; modifies and folds proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

ER lacking ribosomes; synthesizes lipids and detoxifies certain chemicals.

Golgi Apparatus

Stack of membrane layers that modifies, sorts, and packages proteins for transport.

Mitochondrion

Organelle that converts nutrient energy into ATP; the cell’s ‘powerhouse.’

Lysosome

Membrane sac containing digestive enzymes that break down substances inside the cell.

Peroxisome

Organelle containing enzymes that neutralize harmful substances like hydrogen peroxide.

Proteasome

Barrel-shaped complex that degrades misfolded or damaged proteins.

Vesicle

Small membrane-bound sac used to store or move materials within or out of the cell.

Centriole

Rod-shaped structure that helps organize spindle fibers during mitosis.

Cilia

Short, hairlike surface projections that move fluids across cell surfaces.

Flagellum

Long, whip-like projection that propels a cell; in humans, found only on sperm.

Selective Permeability

Property of the plasma membrane that allows some substances to cross while restricting others.

Lipid-Soluble Substance

Hydrophobic molecule, such as steroid hormones or gases, that diffuses freely through lipid bilayers.

Water-Soluble Substance

Hydrophilic molecule, like glucose or ions, that requires membrane proteins to cross the membrane.

Diffusion

Passive movement of particles from an area of higher to lower concentration.

Facilitated Diffusion

Passive transport in which a membrane protein helps a solute move down its gradient.

Osmosis

Diffusion of water through a semipermeable membrane from lower solute concentration to higher solute concentration.

Tonicity

Relative concentration of solutes in two fluids separated by a membrane, affecting cell volume.

Isotonic Solution

Solution with solute concentration equal to that inside the cell; no net water movement.

Hypotonic Solution

Solution with lower solute concentration than the cell; water enters and the cell may swell or burst.

Hypertonic Solution

Solution with higher solute concentration than the cell; water leaves and the cell shrinks.

Osmotic Pressure

The force required to prevent water movement across a membrane due to solute concentration differences.

Active Transport

Energy-requiring movement of substances against their concentration gradient via membrane pumps.

Sodium–Potassium Pump

ATP-driven transporter that moves Na⁺ out and K⁺ into cells against their gradients.

Endocytosis

Vesicular process that brings materials into the cell by engulfing them with plasma membrane.

Phagocytosis

Type of endocytosis in which large particles are engulfed; ‘cell eating.’

Pinocytosis

Endocytic intake of fluid and dissolved substances; ‘cell drinking.’

Exocytosis

Vesicular process that expels materials from the cell by fusing vesicles with the plasma membrane.

DNA (Deoxyribonucleic Acid)

Double-stranded helix in the nucleus that stores the genetic code for protein synthesis.

Gene

Segment of DNA containing the code for a specific protein.

RNA (Ribonucleic Acid)

Single-stranded nucleic acid that helps translate the genetic code into proteins.

Messenger RNA (mRNA)

RNA copy of a DNA gene that carries the code from nucleus to ribosome.

Ribosomal RNA (rRNA)

RNA that, with proteins, forms ribosomes, the sites of protein synthesis.

Transfer RNA (tRNA)

RNA molecule that delivers specific amino acids to the ribosome during protein assembly.

Transcription

First step of protein synthesis; DNA code is copied into mRNA in the nucleus.

Translation

Second step of protein synthesis; ribosomes decode mRNA to build a polypeptide chain.

Mitosis

Type of cell division producing two identical somatic daughter cells (2n).

Meiosis

Cell division that produces gametes with half the chromosome number (n).

Prophase

First mitotic stage where chromosomes condense and the nuclear envelope disappears.

Metaphase

Mitotic stage where chromosomes align across the cell’s equator.

Anaphase

Mitotic stage where sister chromatids separate and move toward opposite poles.

Telophase

Final mitotic stage where nuclear membranes reform around chromosomes at each pole.

Cytokinesis

Division of the cytoplasm, completing cell division into two daughter cells.

Apoptosis

Programmed cell death that removes damaged or unneeded cells.

Metastasis

Spread of cancer cells from the original site to distant tissues.

Cancer Risk Factors

Conditions increasing cancer likelihood, including heredity, chemicals, radiation, obesity, inactivity, poor nutrition, and infectious agents.