Introduction to Cell and Molecular Biology – Vocabulary

A comprehensive set of vocabulary flashcards covering key terms, structures, processes, and diseases introduced in the lecture on cell and molecular biology.

Unifying biological concept stating that cells are the basic units of structure and function, all organisms are composed of one or more cells, and all cells arise from pre-existing cells.

Cell Theory

The original three statements of cell theory: (1) cells are the basic living units, (2) all organisms are made of cells, and (3) cells come only from other cells.

Classical Cell Theory

Extension of classical theory adding that (a) DNA is passed during cell division, (b) cells of a species are similar in structure and chemistry, and (c) energy flow occurs within cells.

Modern Cell Theory

German botanist (1838) who concluded that all plants consist of cells.

Matthias Schleiden

German zoologist (1839) who stated that all animals consist of cells.

Theodor Schwann

German scientist (1855) who proposed that new cells form only by division of existing cells (Omnis cellula e cellula).

Rudolf Virchow

German biologist (1880) who noted that all living cells share a common ancestry traceable to ancient cells.

August Weismann

The ability of a cell or organism to maintain a stable internal environment (e.g., regulation of blood glucose).

Homeostasis

Selective phospholipid bilayer that encloses cell contents and separates them from the external environment.

Plasma Membrane

Specialized membrane-bound structure within a cell that performs a specific metabolic or structural function.

Organelle

Small cell lacking a membrane-bound nucleus; DNA resides in a nucleoid. Found in bacteria and archaea.

Prokaryotic Cell

Larger cell type with membrane-bound organelles and a true nucleus containing DNA.

Eukaryotic Cell

Region in a prokaryotic cell where circular DNA is concentrated; not enclosed by a membrane.

Nucleoid

Long, whip-like appendage that propels many prokaryotic cells like a propeller.

Flagellum

Short, hair-like projections of prokaryotes used for adhesion to surfaces or other cells.

Fimbriae

Extracellular rigid layer surrounding the plasma membrane of bacteria, fungi, and plants for support and protection.

Cell Wall

Entire cell contents outside the nucleus, including cytosol and organelles.

Cytoplasm

Fluid portion of cytoplasm in which organelles are suspended.

Cytosol

Dynamic protein framework (microfilaments, microtubules, intermediate filaments) that gives eukaryotic cells shape and aids transport.

Cytoskeleton

Photosynthetic organelle in plant and algal cells that converts sunlight into chemical energy.

Chloroplast

Large membrane-bound sac in plant cells used for storage, waste disposal, and maintaining turgor pressure.

Vacuole

Double-membrane organelle that generates ATP through aerobic respiration; about the size of small bacteria.

Mitochondrion

Prominent, 5 µm-diameter organelle that stores most cellular DNA and controls gene expression.

Nucleus

Double membrane surrounding the nucleus; contains nuclear pores for molecular traffic.

Nuclear Envelope

Protein-lined opening in the nuclear envelope that regulates exchange between nucleoplasm and cytoplasm.

Nuclear Pore

Fibrous protein network underlying the inner nuclear membrane; supports nucleus and organizes DNA.

Nuclear Lamina

Rare genetic disorder (HGPS) caused by defective nuclear lamina protein progerin, leading to rapid aging in children.

Progeria

Group of inherited diseases causing progressive muscle weakness, linked to mutations affecting structural proteins (including some lamina-associated).

Muscular Dystrophy

Process by which DNA makes an exact copy of itself before cell division.

Replication

Complex of DNA, RNA, and proteins forming granular material in interphase nucleus.

Chromatin

Highly condensed, organized structure of DNA and proteins visible during cell division.

Chromosome

Flow of genetic information: DNA → RNA (transcription) → Protein (translation).

Central Dogma

RNA-protein complex that reads mRNA and synthesizes polypeptides; exists free in cytosol or bound to rough ER.

Ribosome

Prokaryotic ribosome composed of 50S large and 30S small subunits (S = Svedberg units).

70S Ribosome

Sedimentation coefficient unit measuring how fast a particle sediments; indicates size and shape of ribosomal subunits.

Svedberg Unit (S)

Network of membranous sacs and tubules continuous with nuclear envelope; includes rough and smooth regions.

Endoplasmic Reticulum (ER)

ER lacking ribosomes; synthesizes lipids, stores Ca²⁺, detoxifies drugs, and breaks down glycogen (especially in liver cells).

Smooth Endoplasmic Reticulum (SER)

ER studded with ribosomes; synthesizes and folds proteins destined for secretion or organelles.

Rough Endoplasmic Reticulum (RER)

Internal fluid-filled space enclosed by ER membranes where newly synthesized proteins enter for processing.

ER Lumen

Protein that assists the proper folding of other proteins within the ER and cytosol.

Molecular Chaperone

Cytosolic protein complex that degrades misfolded or damaged proteins tagged for destruction.

Proteasome

Stack of flattened cisternae that modifies, sorts, and packages proteins and lipids from the ER.

Golgi Apparatus

Individual flattened membrane sacs composing the Golgi apparatus.

Cisternae

‘Receiving’ side of Golgi stack closest to the nucleus/ER; accepts transport vesicles.

Cis Face

‘Shipping’ side of Golgi facing the plasma membrane; releases processed vesicles.

Trans Face

Acidic, enzyme-filled vesicle that digests macromolecules and defective organelles in animal cells.

Lysosome

Genetic disorder where lack of Hexosaminidase A enzyme leads to GM2 ganglioside accumulation and neurodegeneration.

Tay-Sachs Disease

Lysosomal enzyme that breaks down GM2 ganglioside; its absence causes Tay-Sachs disease.

Hexosaminidase A (Hex-A)

Lipid that accumulates in neurons when Hex-A is absent, triggering Tay-Sachs pathology.

GM2 Ganglioside

One-millionth of a meter; common unit for measuring cells (e.g., bacteria 1–10 µm, eukaryotic cells 10–30 µm).

Micrometer (µm)

One-billionth of a meter; used to measure sub-cellular structures like ribosomes and proteins.

Nanometer (nm)

Laboratory method that separates cellular components by size and density using differential centrifugation.

Cell Fractionation

Techniques (light or electron) that magnify and resolve structures too small for the unaided eye, critical for cell study.

Microscopy