Cells and Microorganisms
Prokaryotes
Prokaryotic cells are the simplest form of life. Consisting of a single cell, bound by a cell membrane, they are microscopic and contain relatively few parts. They have no nucleus; rather their DNA is clumped up, and floating in the cytoplasm. Ribosomes are also floating in the cytoplasm. Most have flagella for movement. These organisms are found in almost every habitat on Earth, including very harsh environments such as hyper saline (halophiles) and extreme temperature (thermophiles). Locally we have salt ponds that are stained various hues of the rainbow as evaporating water changes the salinity and different species of these organisms can survive.
Eukaryotes
Eukaryotes are more complex cells that have both a nucleus and specialized membrane bound organelles. They can be found as single celled organisms or can join together to form the macroscopic flora and fauna found all around us. Different organelles each have their own functions to keep the cell alive. The nucleus is generally the largest and most obvious feature, responsible for the regulation of cell processes, and can be thought of as the brain of the cell. The DNA is enclosed by the nuclear membrane and is the site where transcription takes place. After the nucleus the mitochondria are one of the most noticeable organelles. These kidney bean shaped structures have a double membrane and are the powerhouse of the cell, converting the chemical energy of food into ATP for the cell’s needs. Endoplasmic reticulum (the ER) act as conveyor belts moving cellular products around inside the cell. ER that has ribosomes found on it is called rough ER and is the site of protein manufacturing. The Golgi apparatus can be compared to UPS in that they process and package cell products. Lysosomes function as trashcans disposing of waste products. Animal cells tend to be round or blob-like where as plants have an additional structure in a cell wall for structure and support, generally giving a rectangular shape to the cell.
Some species of organisms (both prokaryotes and eukaryotes) can be parasitic, invading other cells or larger organisms to derive their nutrition from them.
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