bio celluar divide

Prokaryotes

A simple, single-celled organism that lacks a membrane-bound nucleus and other membrane-bound organelles.

Eukaryotes

A complex cell characterized by the presence of a true, membrane bound nucleus and specialized membrane-bound organelles.

Endosymbiotic Theory

The exact mechanism that connects cell biology to organismal diversity; it explains how prokaryotic components became the defining features of eukaryotic classification.

Tree of Life

A foundational biological metaphor and scientific model that maps the evolutionary relationships between all organisms on Earth, showing how species diverged from shared common ancestors.

Cell Envelope

The collective outer protective layers of a bacterium, which typically includes the plasma membrane, cell wall, and an outer capsule.

Capsule

A sticky, thick outer layer composed of polysaccharides (complex sugars) that acts as a protective barrier.

Cell Wall (Prokaryote)

A rigid mesh-like layer outside the plasma membrane that provides structural support, maintains cell shape, and prevents the cell from bursting.

Plasma Membrane (Prokaryote)

A selectively permeable barrier that controls the movement of substances into and out of the cell.

Cytoplasm (Prokaryote)

The jelly-like fluid that fills the inside of a cell. It is enclosed by the cell membrane and acts as a cushion for the cell's internal structures.

Nucleoid

An open, membrane-less area in the cytoplasm containing the genophore (the main circular, double-stranded chromosome).

Plasmid

A small, circular, independent piece of DNA separate from the main chromosome, often carrying accessory genes like antibiotic resistance.

Ribosomes (Prokaryote)

Tiny cellular structures made of ribosomal RNA (rRNA) and proteins that serve as the site of protein synthesis (Smaller size: 70S).

Pili / Fimbriae

Hair-like appendages on the cell surface used for attachment to other cells or surfaces, and for transferring genetic material.

Flagellum

A long, whip-like appendage that rotates like a propeller to give the cell motility (the ability to swim).

Nucleus

The defining, double-membrane bound organelle that houses and protects the cell's genetic material (linear DNA).

Nucleolus

A dense, spherical structure found inside the nucleus of eukaryotic cells that acts as the primary site for ribosome biogenesis.

Plasma Membrane (Eukaryote)

A selectively permeable barrier that controls the movement of substances into and out of the cell.

Cytoplasm (Eukaryote)

The jelly-like fluid that fills the inside of a cell, enclosed by the cell membrane to act as a cushion for internal structures.

Cytoskeleton

An internal framework of protein filaments that gives the cell its shape, organizes internal components, and drives cellular movement.

Mitochondria

The membrane-bound "powerhouses" of the cell where aerobic cellular respiration occurs, converting nutrients into usable energy (ATP).

Endoplasmic Reticulum

A vast network of folded membranes involved in the synthesis of proteins (Rough ER, studded with ribosomes) and lipids (Smooth ER).

Golgi Apparatus

Also known as the Golgi body or Golgi complex, it is an organelle that processes and packages proteins and lipid molecules.

Lysosome

A specialized sac containing digestive enzymes used to break down waste materials, cellular debris, and foreign invaders.

Pseudopodia

Temporary, foot-like extensions of the cytoplasm and membrane used by some single-celled eukaryotes for movement and capturing food.

Prokaryote Examples

Escherichia coli (E. coli), Lactobacillus acidophilus, Streptococcus, Cyanobacteria, and Bacillus anthracis.

Eukaryote Examples

Snake blood cell, human skin cell, sunflower cell, mushroom cell, and Amoeba.

Meaning of Name: Prokaryote

"Before nucleus" (Greek).

Meaning of Name: Eukaryote

"True nucleus" (Greek).

Organism Types: Prokaryote

Bacteria and Archaea.

Organism Types: Eukaryote

Plants, Animals, Fungi, and Protists.

Cell Size: Prokaryote vs. Eukaryote

Prokaryotes are very small; Eukaryotes are much larger.

Nucleus Presence: Prokaryote vs. Eukaryote

Absent in Prokaryotes (DNA floats in nucleoid); Present in Eukaryotes (DNA enclosed in nuclear membrane).

DNA Structure: Prokaryote vs. Eukaryote

Prokaryotes have a single, circular loop; Eukaryotes have multiple, linear chromosomes.

Membrane-Bound Organelles: Prokaryote vs. Eukaryote

Absent in Prokaryotes; Present in Eukaryotes (contains specialized internal compartments).

Ribosome Size: Prokaryote vs. Eukaryote

Prokaryotes have smaller 70S ribosomes; Eukaryotes have larger 80S ribosomes.

Cell Wall Composition: Prokaryote vs. Eukaryote

Prokaryotes have peptidoglycan cell walls (in bacteria); Eukaryotes have cellulose/chitin cell walls (in plants/fungi) or completely lack them (in animals).

Cellular Complexity: Prokaryote vs. Eukaryote

Prokaryotes are always unicellular (single-celled); Eukaryotes are mostly multicellular (with some unicellular protists/yeast).

Reproduction: Prokaryote vs. Eukaryote

Prokaryotes reproduce asexually (mostly via binary fission); Eukaryotes reproduce asexually (mitosis) or sexually (meiosis).

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