Why it is said cell is …

Cells make up the smallest level of a living organism such as yourself and other living things. The cellular level of an organism is where the metabolic processes occur that keep the organism alive. That is why the cell is called the fundamental unit of life.

Cells fall into two major categories: eukaryotes and prokaryotes.

Eukaryotes are organisms that contain chromosomes, including plants and animals, as well as fungi (like mushrooms), protozoa, and most algae. Eukaryotes have the following characteristics:

• They have a nucleus that stores their genetic information.

• Animal cells have an organelle called a mitochondria that effectively combines oxygen and food to convert energy to a useable form.

• Plant cells have chloroplasts<i>,</i> which use energy from sunlight to create food for the plant.

• Eukaryotic cells have internal membranes, which create compartments inside the cells that have different functions.

• Plants cells have a cell membrane and a cell wall, which is rigid; animal cells have only a cell membrane, which is soft.

• The cytoskeleton, which reinforces the cytoplasm of the cell, controls cellular movements.

Prokaryotes are cellular organisms that do not have a “true” nucleus. A <i>nucleus</i> is the control center of a cell. A nucleus contains the genetic material packed into chromosomes, and it is associated with other organelles that function in the production of amino acids and proteins based on what the genetic material dictates. Prokaryotes have some genetic material, but it is not as well organized as it is in eukaryotes. Still, prokaryotes are able to reproduce. Examples of these organisms include bacteria and blue-green algae.