Cell: The Unit of Life

Flashcards for key vocabulary and concepts from the lecture notes on the cell's structure, function, and discovery.

Cell

The fundamental structural and functional unit of all living organisms.

Robert Hooke

Discovered cells in a cork cell (dead plant cell) and observed their honeycomb appearance, calling them 'cellulae'.

Anton von Leeuwenhoek

Discovered living cells, including bacteria, protozoa, human sperm, and RBCs.

Robert Brown

Discovered the nucleus in root cells of epiphytes (orchids).

Schleiden (1838)

German Botanist who stated that all plants are made up of unit structures.

Schwann (1839)

German Zoologist who stated animal cells have a thin covering (plasma membrane) and that plant and animal bodies are made up of unit structures.

Cell Theory

1) cell is the structural unit of life; 2) cell is the functional unit of life- all metabolic reactions occur in the cytoplasm.

Rudolf Virchow (1855)

Explained that cells divide and new cells are formed from pre-existing cells (Omnis cellula-e cellula), giving the cell theory its final shape.

Modern Cell Theory

1) All living organisms are composed of cells and products of cells; 2) All cells arise from pre-existing cells.

Mycoplasma size

Approximately 0.3 μm.

PPLO size

Approximately 0.1 μm.

Bacteria size

Ranges from 1-2 μm.

Virus size

Ranges from 0.02-0.2 μm.

RBC size

Approximately 7 μm.

Eukaryotic cell size

Ranges from 10-20 μm.

Prokaryotic Cell

Small cell that contains a primitive nucleus, no nuclear membrane, histones, or true chromosomes.

Eukaryotic Cell

Large cell that contains a well-developed nucleus, a nuclear membrane, histones, and true chromosomes.

Glycocalyx

A layer surrounding the cell wall of bacteria that provides a sticky character to the bacterial cell.

Gram Staining

Developed by Christian Gram, used to differentiate bacteria based on their cell wall structure.

Gram-positive bacteria

Take up crystal violet stain during Gram staining.

Cilia and Flagella

Both have 9+2 arrangement of microtubules and are protective outgrowth structures of the cytoplasm.

Tubulin

Principle protein of cilia and flagella.

Motile bacteria

Able to move by flagella.

Fimbriae

Structures that help some bacteria to attach to rocks or host tissue.

Prokaryote reserve food material

Glycogen and oil.

Mesosomes

Infoldings of the cell membrane that help in cell wall formation, DNA replication, and respiration, increasing the surface area of the plasma membrane.