Cell: The Unit of Life - Vocabulary Flashcards

Vocabulary flashcards reviewing core cell biology concepts, historical contributions to cell theory, organelle properties, and cell size variations.

Matthias Schleiden

A German botanist who in 1838 examined a large number of plants and observed that all plants are composed of different kinds of cells which form the tissues of the plant.

Theodore Schwann

A British zoologist who in 1839 reported that animal cells have a thin outer layer called the plasma membrane, noted that a cell wall is a unique character of plant cells, and proposed that organisms are composed of cells and products of cells.

Omnis cellula-e cellula

A generalization given by Rudolf Virchow in 1855 stating that cells divide and new cells are formed from pre-existing cells.

Cytoplasm

A semi-fluid matrix occupying the volume of the cell that acts as the main arena of cellular activities where chemical reactions occur to keep the cell in a living state.

70S Ribosome

A membraneless universal ribosome found in prokaryotes, mitochondria, and chloroplasts, composed of a $50\text{S}$ large subunit and a $30\text{S}$ small subunit.

80S Ribosome

A eukaryotic ribosome found in cytoplasm and on rough endoplasmic reticulum, composed of a $60\text{S}$ large subunit and a $40\text{S}$ small subunit.

Centrosome

A non-membrane bound organelle containing centrioles that is present in animal cells but absent in plant cells, helping in cell division.

Mycoplasma

The smallest living cells, lacking a cell wall and measuring only $0.3\,\mu\text{m}$ in length.

Human Red Blood Cells

Erythrocytes characterized by a round and biconcave shape with a diameter of about $7.0\,\mu\text{m}$.

Virus

A non-living entity measuring $0.02\,\mu\text{m}$ to $0.2\,\mu\text{m}$ that acts as an exception to the cell theory.