Cell Structure: Cell Theory and Internal Organelles

Vocabulary-style flashcards covering cell theory, the differences between prokaryotes and eukaryotes, organelle functions, and membrane structure based on the Labster manual.

Robert Hooke

The scientist who, in 1665, first named "cells" after the small rooms inhabited by monks.

Matthias Jakob Schleiden

A botanist who contributed to the cell theory by finding that all plants he examined were made of cells.

Theodor Schwann

A physiologist who discovered in 1839 that animal tissues are composed of cells and helped postulate the first two tenets of cell theory.

Rudolf Virchow

A pathologist who added the third tenet to cell theory in 1855, stating that all cells come from pre-existing cells.

Three Tenets of Cell Theory

1. All living organisms are composed of cells; 2. Cells are the structural and organizational unit of life; 3. All cells come from pre-existing cells.

Prokaryotic Cells

Single-cell organisms, such as bacteria and archaea, that lack a nucleus and specialized organelles like the endoplasmic reticulum or Golgi apparatus.

Eukaryotic Cells

Cells found in animals, plants, protists, and fungi that contain a nucleus and more specialized organelles.

Five Shared Components of All Cells

The plasma membrane, cytoplasm, DNA, ribosomes, and a cytoskeleton.

Eukaryotic Ribosomes

Ribosomes consisting of a $60S$ large subunit and a $40S$ small subunit, forming an $80S$ complete ribosome.

Prokaryotic Ribosomes

Ribosomes characterized as being $70S$ in size.

Nucleoid

A region in the cytoplasm of prokaryotic cells where the DNA is found freely.

Plasmids

Small circular DNA fragments that can replicate independently of nuclear DNA; found naturally in prokaryotes, fungi, and certain plants.

Cell Membrane

A semi or selectively permeable double layer of phospholipids that separates and protects the cell from its environment.

Cytoplasm

All material in the cell excluding the nucleus, comprised of the gel-like cytosol and other organelles.

Nucleus

The organelle containing most of a cell's DNA organized as linear chromosomes, separated from the cytoplasm by the nuclear envelope.

Mitochondria

The powerhouses of the mammalian cell that generate chemical energy in the form of adenosine triphosphate ($ATP$).

Rough Endoplasmic Reticulum (RER)

An organelle studded with protein-producing ribosomes that serves as the major source of protein translation.

Smooth Endoplasmic Reticulum (SER)

An organelle involved in the metabolism of lipids and the formation of cholesterol and phospholipids for fresh cellular membranes.

Golgi Apparatus

An organelle that functions as a continuation of the endomembrane system to package proteins for dispersal via secretory vesicles.

Lysosome

A cellular recycling center rich in enzymes responsible for breaking down various biomolecules into constituent parts.

Peroxisome

An organelle that functions as a hazardous waste recycling center by reducing damaging reactive oxygen species into harmless waste products.

Fluid Mosaic Model

A description of the plasma membrane as a mosaic of phospholipids, cholesterol, proteins, and carbohydrates with a thickness of $5$ to $10\,nm$.

Cell Wall

A rigid structure outside the cell membrane providing strength; composed of cellulose in plants, chitin in fungi, and peptidoglycan in bacteria.

Endosymbiosis Theory

The hypothesis that eukaryotic organelles like mitochondria and chloroplasts originated from a symbiotic relationship where a larger bacteria ingested a smaller one.

Binary Fission

The method of division used by chloroplasts and mitochondria, which is typical of prokaryotes and serves as evidence for endosymbiosis.