Prokaryotic and Eukaryotic Cells

Learning Objectives

• Name examples of prokaryotic and eukaryotic organisms

• Compare and contrast prokaryotic cells and eukaryotic cells

• Describe the relative sizes of different kinds of cells

Cell Types

• Cells are either prokaryotic or eukaryotic.

• Prokaryotes: Bacteria and Archaea (single-celled).

• Eukaryotes: Animal cells, plant cells, fungi, and protists.

Prokaryotic Cells

• Simple, unicellular organisms.

• Lack a nucleus or any membrane-bound organelle.

• Components:

  • Plasma membra ne

  • Cytoplasm

  • DNA (in nucleoid region)

  • Ribosomes

• Bacteria have a cell wall made of peptidoglycan and a polysaccharide capsule.

• Some have flagella (locomotion), pili (genetic material exchange).

Eukaryotic Cells

• Have a membrane-bound nucleus and other membrane-bound organelles.

• Organelles have specialized functions.

Cell Size

• Prokaryotic cells: 0.1–5.0 µm in diameter.

• Eukaryotic cells: 10–100 µm in diameter.

• Small prokaryotic size allows quick diffusion of molecules.

• Larger eukaryotic cells have structural adaptations for transport.

• Cell size is limited by the surface area to volume ratio.