Cell Theory and Cell Structure Vocabulary

Vocabulary flashcards generated from lecture notes on cell theory, prokaryotic and eukaryotic structures, and eukaryotic organelles.

Cell Theory

A foundational biological tenet consisting of three core statements: 1. All living things are composed of cells; 2. The cell is the basic unit of life; 3. Cells arise from preexisting cells.

Cell

The basic structural unit of life, defined as the smallest unit capable of using energy to sustain itself in a highly ordered state.

Scientific Theory

A well-substantiated explanation of an aspect of the natural world acquired through the scientific method and repeatedly confirmed through observation and experimentation.

Cell Differentiation

The process by which cells in multicellular organisms specialize to take on specific shapes and perform specific functions.

Prokaryotic Cell

A simple, tiny cell (approx. $0.2 - 10\text{ }\frac{1}{1000}\text{mm}$ / $0.2 - 10\text{ }\frac{1}{10^6}\text{m}$) that evolved around $3.8\text{ bya}$, lacks a nucleus and membrane-bound organelles, and contains circular naked DNA in the cytoplasm.

Eukaryotic Cell

A complex, larger cell (approx. $10 - 100\text{ }\frac{1}{1000}\text{mm}$) that evolved around $2.7\text{ bya}$, containing a membrane-bound nucleus with linear DNA wrapped around histone proteins, as well as membrane-bound organelles.

Organelle

A specialized structure within a cell that performs a specific function, analogous to an organ in a body.

Cell Membrane

A protective phospholipid bilayer surrounding every cell that regulates what enters and exits the cell according to the fluid mosaic model.

Cytosol

The liquid, gel-like part of the cytoplasm made of water and dissolved solutes such as salts, fatty acids, sugars, amino acids, and enzymes.

Ribosomes

Cellular structures composed of two subunits responsible for building polypeptide chains and proteins.

Nucleoid

The region within a prokaryotic cell's cytoplasm where its circular DNA is located.

Prokaryotic Cell Wall

An outer structure that provides shape and allows the prokaryotic cell to withstand turgor pressure without bursting.

Capsule

An outer structure present in some prokaryotic cells that prevents dehydration and aids in adhering to surfaces.

Flagellum

A long cellular extension used primarily for cell locomotion.

Pili

Hair-like extensions found on some prokaryotes that enable attachment to surfaces, swapping of DNA with other cells, or harpooning environmental DNA.

Nucleus

A double-membraned eukaryotic organelle with pores that encloses DNA (the genetic blueprint for making proteins) and contains the nucleolus.

Nucleolus

A structure located inside the eukaryotic nucleus where ribosomes are synthesized.

Mitochondria

Eukaryotic organelles that produce energy for the cell in the form of ATP through cellular respiration.

Endoplasmic Reticulum (E.R.)

A series of flattened membranes surrounding the nucleus in eukaryotic cells.

Rough E.R.

The portion of the endoplasmic reticulum studded with bound ribosomes that acts as a transport network for proteins.

Smooth E.R.

The portion of the endoplasmic reticulum that lacks ribosomes, synthesizes lipids, and participates in membrane repair.

Free Ribosomes

Ribosomes floating freely in the cytoplasm that synthesize proteins intended for use inside the cell.

Bound Ribosomes

Ribosomes attached to the rough endoplasmic reticulum that synthesize proteins destined to be sent out of the cell.

Golgi Apparatus

An organelle discovered by Camillo Golgi that modifies, sorts, concentrates, and packages proteins into vesicles for transport inside or outside the cell.

Binary Fission

The division process by which prokaryotic cells reproduce to form new cells.