Cell: The Fundamental Unit of Life Flashcards

Vocabulary-style flashcards covering the basic definitions, history, structures, and differences between cell types as described in the lecture notes.

Cell

The basic structural and functional unit of living organisms that makes up living things and carries out activities to keep them alive.

Cell Theory

A collection of ideas concluding that all living things are made of one or more cells, the cell is the basic unit of structure and function, and all cells arise from pre-existing cells.

Robert Hooke

The scientist who discovered the cell in 1665.

Anton Van Leeuwenhoek

The scientist who observed the first living cell in 1674.

Robert Brown

The scientist who discovered the nucleus in 1883.

Felix Dujardin

The scientist who discovered the fluid content of the cell in 1835.

Matthias Schleiden

The scientist who proposed in 1838 that all plants are made up of cells.

J. E. Purkinje

The scientist who named the fluid content of the cell as protoplasm in 1839.

Theodor Schwann

The scientist who proposed in 1839 that all animals are made up of cells.

Carl Heinrich Braun

The scientist who proposed that the cell is the basic unit of life in 1845.

Rudolf Virchow

The scientist who proposed in 1855 that all cells arise from pre-existing cells.

Unicellular Organism

An organism made up of only one cell, such as Euglena, Paramecium, or Yeast.

Multicellular Organism

An organism made up of more than one cell, such as plants, animals, and fungi.

Micrometer ($\mu m$)

The unit used to measure the size of a cell, where $1\,\mu m = 1/1000\,millimeter$.

Mycoplasma

Recognized as the smallest cell, with a size of $0.1\,\mu m$.

Ostrich egg

Recognized as the largest cell, with a size of $18\,cm$.

Nerve cell

The longest cell in the human body, reaching a size of $1\,m$.

Ultrastructure

The detailed structure of a cell as seen under an electron microscope.

Plasma Membrane

An extremely delicate, thin, elastic, living, and semi-permeable membrane made of two layers of lipid molecules and floating proteins.

Cell Wall

The non-living, tough, rigid, and outermost covering of plant and bacterial cells made of cellulose, hemicellulose, and pectin.

Nucleus

A dense spherical body located near the center of the cell that acts as the control center for activities like metabolism and growth.

Nucleoplasm

The colorless dense sap present inside the nucleus containing the nucleolus and chromatin fibers.

Chromatin

A network of fibers in the nucleus composed of deoxyribonucleic acid (DNA) and protein histone that condense into chromosomes during division.

Genes

Stretches of DNA that store and transfer hereditary information from one generation to the next.

Cytoplasm

A jelly-like material formed by 80% water located between the plasma membrane and the nucleus.

Endoplasmic Reticulum (ER)

A network of interconnected tubular and vesicular structures; includes Rough ER (with ribosomes) and Smooth ER (lacking ribosomes).

Golgi Body

Organelle formed by stacks of flattened membranous sacs called cisternae that modifies, sorts, and packs materials for delivery.

Lysosomes

Small, single-membrane sacs filled with hydrolytic enzymes that digest large molecules and perform autolysis in dead cells.

Vacuoles

Single-membrane sacs filled with liquid or sap used to store substances and maintain osmotic pressure/turgidity.

Mitochondria

Small, rod-shaped organelles with a folded inner membrane (cristae) that synthesize energy-rich ATP molecules.

Plastids

Double membrane-bound organelles in plants and algae responsible for making and storing food, often containing pigments.

Chromoplasts

Plastids that produce and store pigments like carotene, xanthophyll, and lycopene, giving color to fruits and vegetables.

Leucoplasts

Colorless plastids found in storage organs that store food such as starch, protein, or oil.

Chloroplasts

Plastids containing chlorophyll molecules in stacks of thylakoids (grana) that convert light energy into chemical energy.

Centrosome

A membrane-bound organelle near the nucleus consisting of two centrioles that form spindle fibers during cell division.

Cytoskeleton

A structure formed by microtubules (tubulin) and microfilaments (actin) that determines cell shape and provides structural strength.

Prokaryotic Cell

A cell with an undeveloped nucleus, no membrane-bound organelles, and a size ranging from $0.5-5\,\mu m$.

Eukaryotic Cell

A cell with a well-developed nucleus, membrane-bound organelles, and more than one chromosome, ranging from $5-100\,\mu m$.