The Cell Theory and Organelles

A comprehensive set of vocabulary flashcards covering the discovery of cells, the scientists involved in Cell Theory, and the specific organelles and their functions in plant and animal cells.

Cell

The basic structural and functional unit of all living organisms and the smallest unit of life capable of performing all life processes.

Animal Cell

An irregularly shaped eukaryotic cell with a flexible membrane, ranging between $10$ to $30\,\text{micrometers}$ in size, which lacks a cell wall.

Nucleus

The organelle containing DNA ($\text{the genetic blueprint}$) that acts as the control center of the cell and manages its activities.

Cytosol

The fluid within the cell that surrounds the organelles.

Golgi apparatus

A membrane-bound sac responsible for modifying, sorting, packaging, and transporting proteins and lipids; often called the cell's post office.

Lysosome

An organelle containing digestive enzymes that acts as a clean-up crew or recycling center by breaking down waste and biological molecules.

Centrosome

An organelle near the nucleus that organizes microtubules and helps with the production of spindle fibers during cell division.

Endoplasmic reticulum (ER)

A network of membranes that serves as the manufacturing and transport system of the cell for proteins and lipids.

Ribosome

Small organelles, either floating or attached to the rough ER, that act as protein factories by performing protein synthesis.

Cell membrane

Also called the plasma membrane, it consists of two layers of lipid molecules that regulate the movement of substances in and out of the cell to maintain homeostasis.

Vacuole

A membrane-bound storage sac for water, nutrients, and waste; plant cells typically have one large central vacuole while animal cells have smaller ones.

Mitochondrion

The powerhouse of the cell responsible for converting raw materials into usable energy ($\text{ATP}$) through cellular respiration.

Plant Cell

A eukaryotic cell characterized by a rigid cell wall, chloroplasts for photosynthesis, and a rectangular shape.

Chloroplast

An organelle found only in plant cells that is responsible for photosynthesis.

Cell Wall

A strong, protective outer layer found in plants ($\text{cellulose}$), fungi ($\text{chitin}$), and bacteria ($\text{peptidoglycan}$) that provides shape and support.

Prokaryotic cell

Simple, usually unicellular cells without a true nucleus, where DNA is found in the cytoplasm ($\text{e.g., Bacteria and Archaea}$).

Eukaryotic cell

Complex cells that contain a true nucleus and membrane-bound organelles ($\text{e.g., plants, animals, fungi, and protists}$).

Robert Hooke

An English scientist who coined the term "cell" in $1665$ after observing thin slices of cork under a microscope.

Antonie van Leeuwenhoek

Known as the "Father of Microbiology," he was the first to observe living cells and microorganisms in $1674$ using powerful single-lens microscopes.

Robert Brown

A Scottish botanist who discovered and named the nucleus in plant cells in $1831$.

Matthias Schleiden

A German botanist who concluded in $1838$ that all plants are composed of cells.

Theodor Schwann

A German zoologist who concluded in $1839$ that all animals are made of cells, helping to establish the Cell Theory.

Rudolf Virchow

A scientist who completed the Cell Theory in $1855$ by proposing that all cells come from pre-existing cells ($\text{Omnis cellula e cellula}$).

Nucleolus

A structure within the nucleus responsible for producing ribosomes.

Cytoplasm

The jelly-like substance where organelles are found within the cell membrane.

Peroxisome

The cell's detoxification center that breaks down fatty acids and detoxifies harmful substances, especially abundant in liver cells.

Rough Endoplasmic Reticulum (RER)

A region of the ER with ribosomes attached to its surface that produces and transports proteins.

Smooth Endoplasmic Reticulum (SER)

A region of the ER without ribosomes that produces lipids, helps detoxify substances, and stores minerals like calcium.

Vesicle

A small sac that acts as a delivery truck to store and transport materials between organelles and the cell membrane.

Cytoskeleton

The internal framework made of microtubules and filaments that provides support, shape, and organization to the cell.

Extracellular Matrix (ECM)

A network of materials outside animal cells, containing proteins like collagen, that supports, connects, and protects cells in tissues.

Tight Junctions

Cell junctions that form a seal between cells to prevent substance leakage.

Desmosomes

Cell junctions that act like rivets or buttons to hold cells tightly together, common in skin and heart tissue.

Gap Junctions

Cell junctions that form channels allowing small molecules and signals to pass directly between neighboring cells.

Centriole

A small cylindrical structure made of microtubules that helps the cell divide, usually found in pairs within a centrosome.