Cell: The Unit of Life – Vocabulary Flashcards

A comprehensive set of vocabulary flashcards summarising essential terms and definitions from the lecture on basic cell biology.

Cell

Smallest structural and functional unit of life, capable of independent existence and all essential life processes.

Protoplasm

The total living substance of a cell, comprising cytoplasm plus nucleus.

Cytoplasm

Semi-fluid portion of protoplasm between nucleus and cell membrane where most metabolic reactions occur.

Cell Membrane (Plasma Membrane)

Living, selectively permeable lipoprotein boundary that encloses the cell and regulates substance movement.

Cell Wall

Non-living, cellulose outer layer of plant cells that provides shape, support, and freely permeable protection.

Selectively Permeable

Property of the cell membrane allowing passage of some substances while restricting others.

Nucleus

Membrane-bound organelle that controls cellular activities and houses genetic material.

Nucleoplasm

Dense fluid inside the nucleus containing chromatin and nucleolus.

Nucleolus

Dark, spherical body in nucleus responsible for ribosome subunit formation.

Chromatin

Thread-like DNA–protein network in non-dividing nucleus that condenses into chromosomes during division.

Chromosome

Rod-like structure of condensed chromatin carrying genes; humans have 46 in somatic cells.

Gene

Hereditary unit on a chromosome controlling a specific trait.

DNA (Deoxyribonucleic Acid)

Molecular substance of genes that stores and transmits hereditary information.

Cell Theory

Principle stating: (1) all organisms are made of cells, (2) cells are basic units of structure and function, (3) all cells arise from pre-existing cells.

Simple Microscope

Magnifying instrument with a single biconvex lens; first built by Antony van Leeuwenhoek.

Compound Microscope

Light microscope using two lens systems to achieve higher magnification; improved by Robert Hooke.

Electron Microscope

Magnification device using electron beams and magnets; resolves up to ~200,000×.

Robert Hooke

English scientist who coined the term “cell” after observing cork with a compound microscope.

Antony van Leeuwenhoek

Dutch microscopist who constructed about 400 simple microscopes and first observed living cells.

Matthias Schleiden

German botanist who proposed that all plants are composed of cells.

Theodor Schwann

German zoologist who extended cell theory to animals; co-author of cell theory.

Rudolf Virchow

Pathologist who added ‘cells arise only from pre-existing cells’ to cell theory.

Prokaryotic Cell

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

Eukaryotic Cell

Cell with a true nucleus and membrane-bound organelles; found in plants and animals.

Organelle

Specialised, membrane-delimited structure within cytoplasm performing a specific function.

Endoplasmic Reticulum (ER)

Network of double membranes forming channels within cytoplasm for transport and synthesis.

Rough ER

ER with ribosomes; synthesises and transports proteins.

Smooth ER

ER lacking ribosomes; involved in lipid synthesis and detoxification.

Ribosome

Tiny RNA–protein particle, free or on RER, that is the site of protein synthesis.

Golgi Apparatus

Stack of membrane-bound cisternae that packages, modifies, and ships cellular secretions.

Dictyosome

Golgi-like structure in plant cells consisting of discrete stacks of cisternae.

Lysosome

Enzyme-filled vesicle for intracellular digestion; nicknamed ‘suicide bag’ of the cell.

Mitochondrion

Double-membrane organelle producing ATP through cellular respiration; the cell’s powerhouse.

ATP (Adenosine Triphosphate)

Immediate chemical energy molecule generated mainly in mitochondria.

Centrosome

Cytoplasmic region in animal cells containing centrioles that organise spindle during division.

Centriole

Short microtubule bundle, usually in pairs, oriented at right angles inside the centrosome.

Plastid

Plant-cell organelle of various colours involved in storage or photosynthesis.

Chloroplast

Green plastid containing chlorophyll that captures light energy for photosynthesis.

Chromoplast

Coloured plastid (yellow, orange, red) rich in carotenoids, giving colour to petals and fruits.

Leucoplast

Colourless plastid that stores starch, oils, or proteins; abundant in potato tuber cells.

Vacuole

Membrane-bound sac containing cell sap; large and central in mature plant cells.

Cell Sap

Fluid within a plant vacuole containing water, salts, sugars, and pigments.

Surface Area : Volume Ratio

Relative measure that becomes larger as cells remain small, enabling efficient diffusion.

Biconcave Shape

Disc shape indented on both sides, characteristic of human red blood cells for flexibility.

Mesosome

Infolded region of prokaryotic cell membrane associated with respiration and DNA replication.

Stem Cell

Undifferentiated cell capable of unlimited division and giving rise to various specialised cells.

Embryonic Stem Cell

Pluripotent stem cell from early embryo that can form any body tissue.

Tissue-specific Stem Cell

Partially specialised stem cell committed to generating cells of a particular tissue, e.g., bone marrow stem cell.

Induced Pluripotent Stem Cell (iPS Cell)

Mature somatic cell reprogrammed chemically to behave like a pluripotent stem cell.

Guard Cell

Bean-shaped epidermal cell that regulates stomatal opening and closing in leaves.

Red Blood Cell (Erythrocyte)

Biconcave, nucleus-free blood cell that transports oxygen via haemoglobin.

Nerve Cell (Neuron)

Longest cell type with branching processes specialised for conducting impulses.

Amoeba

Single-celled, shapeless protozoan that moves and feeds using pseudopodia; example of unicellular eukaryote.

Bacterium

Microscopic, single-celled prokaryote lacking a true nucleus and membrane-bound organelles.

Cell

Smallest structural and functional unit of life, capable of independent existence and all essential life processes.

Protoplasm

The total living substance of a cell, comprising cytoplasm plus nucleus.

Cytoplasm

Semi-fluid portion of protoplasm between nucleus and cell membrane where most metabolic reactions occur.

Cell Membrane (Plasma Membrane)

Living, selectively permeable lipoprotein boundary that encloses the cell and regulates substance movement.

Cell Wall

Non-living, cellulose outer layer of plant cells that provides shape, support, and freely permeable protection.

Selectively Permeable

Property of the cell membrane allowing passage of some substances while restricting others.

Nucleus

Membrane-bound organelle that controls cellular activities and houses genetic material.

Nucleoplasm

Dense fluid inside the nucleus containing chromatin and nucleolus.

Nucleolus

Dark, spherical body in nucleus responsible for ribosome subunit formation.

Chromatin

Thread-like DNA–protein network in non-dividing nucleus that condenses into chromosomes during division.

Chromosome

Rod-like structure of condensed chromatin carrying genes; humans have 46 in somatic cells.

Gene

Hereditary unit on a chromosome controlling a specific trait.

DNA (Deoxyribonucleic Acid)

Molecular substance of genes that stores and transmits hereditary information.

Cell Theory

Principle stating: (1) all organisms are made of cells, (2) cells are basic units of structure and function, (3) all cells arise from pre-existing cells.

Simple Microscope

Magnifying instrument with a single biconvex lens; first built by Antony van Leeuwenhoek.

Compound Microscope

Light microscope using two lens systems to achieve higher magnification; improved by Robert Hooke.

Electron Microscope

Magnification device using electron beams and magnets; resolves up to ~200,000×.

Robert Hooke

English scientist who coined the term “cell” after observing cork with a compound microscope.

Antony van Leeuwenhoek

Dutch microscopist who constructed about 400 simple microscopes and first observed living cells.

Matthias Schleiden

German botanist who proposed that all plants are composed of cells.

Theodor Schwann

German zoologist who extended cell theory to animals; co-author of cell theory.

Rudolf Virchow

Pathologist who added ‘cells arise only from pre-existing cells’ to cell theory.

Prokaryotic Cell

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

Eukaryotic Cell

Cell with a true nucleus and membrane-bound organelles; found in plants and animals.

Organelle

Specialised, membrane-delimited structure within cytoplasm performing a specific function.

Endoplasmic Reticulum (ER)

Network of double membranes forming channels within cytoplasm for transport and synthesis.

Rough ER

ER with ribosomes; synthesises and transports proteins.

Smooth ER

ER lacking ribosomes; involved in lipid synthesis and detoxification.

Ribosome

Tiny RNA–protein particle, free or on RER, that is the site of protein synthesis.

Golgi Apparatus

Stack of membrane-bound cisternae that packages, modifies, and ships cellular secretions.

Dictyosome

Golgi-like structure in plant cells consisting of discrete stacks of cisternae.

Lysosome

Enzyme-filled vesicle for intracellular digestion; nicknamed ‘suicide bag’ of the cell.

Mitochondrion

Double-membrane organelle producing ATP through cellular respiration; the cell’s powerhouse.

ATP (Adenosine Triphosphate)

Immediate chemical energy molecule generated mainly in mitochondria.

Centrosome

Cytoplasmic region in animal cells containing centrioles that organise spindle during division.

Centriole

Short microtubule bundle, usually in pairs, oriented at right angles inside the centrosome.

Plastid

Plant-cell organelle of various colours involved in storage or photosynthesis.

Chloroplast

Green plastid containing chlorophyll that captures light energy for photosynthesis.

Chromoplast

Coloured plastid (yellow, orange, red) rich in carotenoids, giving colour to petals and fruits.

Leucoplast

Colourless plastid that stores starch, oils, or proteins; abundant in potato tuber cells.

Vacuole

Membrane-bound sac containing cell sap; large and central in mature plant cells.

Cell Sap

Fluid within a plant vacuole containing water, salts, sugars, and pigments.

Surface Area : Volume Ratio

Relative measure that becomes larger as cells remain small, enabling efficient diffusion.

Biconcave Shape

Disc shape indented on both sides, characteristic of human red blood cells for flexibility.

Mesosome

Infolded region of prokaryotic cell membrane associated with respiration and DNA replication.

Stem Cell

Undifferentiated cell capable of unlimited division and giving rise to various specialised cells.