The Fundamental Unit of Life – Vocabulary

A set of vocabulary flashcards covering the major terms, structures, scientists and processes discussed in the lecture on the fundamental unit of life.

Cell

Basic structural and functional unit of life; from Latin for ‘a little room’.

Robert Hooke

Scientist who first observed and named cells while examining cork in 1665.

Unicellular Organism

Living being made up of a single cell, e.g., Amoeba, Chlamydomonas, bacteria.

Multicellular Organism

Organism composed of many cells that perform specialized functions.

Cell Theory

Concept that all plants and animals are composed of cells and cells arise from pre-existing cells.

Prokaryote

Cell lacking a true nucleus and membrane-bound organelles; e.g., bacteria.

Eukaryote

Cell containing a true nucleus and membrane-bound organelles.

Plasma Membrane

Outer boundary of the cell; selectively permeable lipid-protein layer.

Selectively Permeable Membrane

Barrier that allows certain substances to pass while restricting others.

Diffusion

Movement of molecules from high to low concentration driven by kinetic energy.

Osmosis

Net diffusion of water across a selectively permeable membrane toward higher solute concentration.

Hypotonic Solution

External medium with higher water (lower solute) concentration than the cell, causing the cell to swell.

Isotonic Solution

Solution with the same water concentration as the cell; no net water movement.

Hypertonic Solution

Medium with lower water (higher solute) concentration than the cell, leading to cell shrinkage.

Endocytosis

Process by which a cell engulfs material from its surroundings.

Cell Wall

Rigid outer layer in plant, fungal and bacterial cells composed mainly of cellulose.

Plasmolysis

Shrinkage of the cell contents away from the cell wall when water is lost by osmosis.

Nucleus

Membrane-bound organelle containing chromosomes and directing cellular activities.

Nuclear Membrane

Double-layered envelope with pores surrounding the nucleus.

Chromosome

Rod-shaped DNA-protein structure carrying hereditary information.

Gene

Functional segment of DNA coding for a specific trait or protein.

Nucleoid

Poorly defined nuclear region in prokaryotic cells lacking a nuclear membrane.

Cytoplasm

Fluid content inside the plasma membrane containing organelles and cytosol.

Organelle

Membrane-bound structure within a eukaryotic cell that performs a specific function.

Endoplasmic Reticulum (ER)

Network of membrane-bound tubules/sacs involved in transport and synthesis.

Rough Endoplasmic Reticulum (RER)

ER studded with ribosomes; site of protein synthesis.

Smooth Endoplasmic Reticulum (SER)

ER lacking ribosomes; synthesises lipids and detoxifies drugs.

Ribosome

Non-membranous particle where proteins are synthesised.

Golgi Apparatus

Stack of membrane-bound cisterns that modify, package and dispatch cell products.

Lysosome

Membrane sac of digestive enzymes; breaks down waste and foreign material; ‘suicide bag’.

Mitochondrion

Double-membranous ‘powerhouse’ producing ATP; contains its own DNA.

ATP (Adenosine Triphosphate)

Energy currency molecule generated in mitochondria.

Plastid

Plant cell organelle involved in photosynthesis or storage; includes chloroplasts, chromoplasts, leucoplasts.

Chloroplast

Green plastid containing chlorophyll; site of photosynthesis.

Chromoplast

Coloured plastid (other than green) containing pigments.

Leucoplast

Colourless plastid primarily for storage of starch, oils or proteins.

Vacuole

Membrane-bound sac for storage; large central one in plant cells maintains turgidity.

Turgidity

State of being swollen with water, providing rigidity to plant cells.

Mitosis

Type of cell division producing two genetically identical daughter cells for growth and repair.

Meiosis

Cell division producing four daughter cells with half the chromosome number; forms gametes.

Electron Microscope

Instrument using electron beams to achieve high-resolution imaging of cell structures.

Protoplasm

Fluid living substance of the cell, term coined by Purkinje in 1839.

Selective Permeability

Characteristic of membranes to regulate substance passage based on size, charge or chemistry.

Membrane Biogenesis

Process of building new cell membranes from lipids and proteins synthesized in the ER.