Cell Biology 1 Flashcards

A set of vocabulary flashcards defining key structures, organelles, and processes covered in Cell Biology Unit 1.

Cell Theory

The biological principle stating that all living things are made of one or more cells, metabolic processes are derived from existing ones, new cells derive from pre-existing cells, and cells possess genetic material passed from parent to daughter cells.

Nuclear Pores

Gaps that perforate the nuclear envelope, each measuring about $80\text{--}100\,\text{nm}$, which allow large molecules such as messenger RNA to move out of the nucleus.

Nucleoplasm

The granular, jelly-like material that forms the main bulk of the nucleus.

Nucleolus

A spherical body situated inside the nucleoplasm that manufactures ribosomal RNA and assembles ribosomes.

Heterochromatin

The region of chromatin in the nucleoplasm that stains very darkly.

Euchromatin

The region of chromatin in the nucleoplasm that is less heavily stained.

80S Ribosomes

The specific type of ribosomes found in eukaryotic cells.

70S Ribosomes

The specific type of ribosomes found in prokaryotic cells.

Ribosomes

Small cytoplasmic granules ($20\,\text{nm}$ in diameter) consisting of one large and one small subunit containing ribosomal RNA and protein; they serve as key sites for protein synthesis.

Cisternae

Flattened membrane-enclosed sacs found within the endoplasmic reticulum and the Golgi body.

Rough Endoplasmic Reticulum (RER)

A system of sheet-like membranes studded with ribosomes on its outer surface that provides a large surface area for protein synthesis and a transport pathway for materials.

Smooth Endoplasmic Reticulum (SER)

A tubular membrane system lacking surface ribosomes that synthesises, stores, and transports lipids and carbohydrates.

Golgi Body

An organelle composed of a stack of membrane-bound cisternae and vesicles that processes, sorts, modifies, and packages proteins and lipids for secretion or delivery to other cell regions.

Lysosomes

Single-membrane-bound spherical vesicles ($0.5\,\mu\text{m}$ in diameter) containing hydrolytic digestive enzymes used to break down foreign materials, ingested particles, worn-out organelles, or dead cells.

Chloroplast Envelope

A double membrane around a chloroplast whose inner membrane folds into lamellae, regulating the entry and exit of substances.

Stroma

The colourless, gelatinous fluid matrix inside a chloroplast that contains DNA, oil droplets, and the enzymes required for the light-independent stage of photosynthesis.

Grana

Stacks of coin-like flattened thylakoid membranes inside a chloroplast that hold chlorophyll molecules and carry out the light-dependent stage of photosynthesis.

Cristae

Infoldings of the inner membrane of a mitochondrion that extend across its interior to increase the surface area for energy production.

Mitochondrial Matrix

The semi-rigid inner material of a mitochondrion containing proteins, lipids, and traces of DNA, serving as the site for the Krebs cycle in aerobic respiration.

Mitochondrion

A rod-shaped organelle ($1\text{--}10\,\mu\text{m}$ long) bounded by a double membrane with cristae and a matrix, responsible for producing energy-rich ATP molecules through respiration.

Tonoplast

The single selective membrane enclosing the large permanent central vacuole in mature plant cells.

Cell Sap

The aqueous solution of dissolved food materials, ions, pigments, and waste products filling the plant cell vacuole.

Centrioles

Hollow cylindrical organelles found in animal cells that organize tubulin microtubules into spindle fibres during nuclear division.

Phospholipid Bilayer

A double layer of lipid molecules with hydrophilic heads directed outward and hydrophobic tails pointing inward, forming the structural foundation of plasma membranes.

Middle Lamella

A pectin-containing layer situated between adjacent plant cell walls that holds neighbouring cells firmly together.

Plasmodesmata

Microscopic, membrane-lined channels running through plant cell walls that connect the cytoplasm of neighboring plant cells.

Leucoplasts

Non-green plastids found in plant tissues (such as potato tubers) that store starch but lack chlorophyll.