Alex Carrington Stephanie Otondi 5th period May 7, 2015
Domains to Know
Domain Archaea is mostly composed of cells that live in extreme environments. While they are able to live elsewhere, they are usually not found there because outside of extreme environments they are competitively excluded by other organisms.
Domain Bacteria is composed of organisms that are much more common than Archaea and live almost anywhere. There are more bacteria in a person's mouth than there are people in the world. Many are decomposers, some are photosynthesizers, and a few cause disease.
The Domain Eukarya arose from the first prokaryotic organisms more than 1.7 billion years ago. It includes all of the organisms with eukaryotic cells--that is, those with membranous organelles (including mitochondria and chloroplasts). The organisms in this domain will be the focus of our classifications; indeed, they represent the vast majority of organisms we see each day. In terms of our classification questions, members of the domain have the following characteristics:
- Eukaryotic cells
- Unicellular (some Protists and yeasts), Colonial (some Protists) or Multicellular (most Fungi, Plantae, and Animalia) organisms
- Cell division by mitosis, with a variety of cycles of reproduction and recombination
- A variety of modes of access to energy and carbon, varying with kingdom
Kingdoms to Know
Archaea evolved many cell sizes, but all are relatively small. The thermoplasmas are the smallest of the archaea. Most archaea fall into size classes (0.1 to 15 μ diameter and up to 200 μ long) matching bacteria. So they are about the size of a mitochondrion in a eukaryotic cell.
Archaea have also evolved into many cell shapes similar to those of bacteria. There are bacilli, cocci, spirilli, and plate-like forms of archaea.
Also like bacteria, the cells of archaea form various associations within a population of cells. Some species are unicellular, others are colonial, and yet others are filamentous.
Bacterial kingdoms are part of the classification scheme that fits bacteria into appropriate groupings based on certain criteria. The kingdom is the broadest classification category.There are two kingdoms of prokaryotes. These are the bacteria (or eubacteria ) and the archaebacteria (or the Archaea ). The members of these two kingdoms appear similar in shape and appearance, even under the extreme magnification of the electron microscope . However, they are very different from each other in a number of molecular and biochemical aspects. It is these differences that have resulted in the microorganisms being grouped into separate kingdoms.
For example, eubacteria contain the rigid, stress-bearing network known as thepeptidoglycan . The only exceptions are the bacteria from the generaMycoplasma and Chlamydia. Archaebacteria do not contain peptidoglycan. Instead, they contain a different structure that is called pseudomurein.
The protists of Kindom Protista are the simplest eukaryotes, yet they represent an incredibly diverse group. Most are unicellular, some are colonial, and other are simple multicellular organisms closely related to single protist cells. One group of protists, the algae, are autotrophic photosynthesizers, while the rest eat bacterial or other protistan cells, or small organic particles suspended or dissolved in water. Due to these feeding habits, and the weakness of non-aquatic locomotion capabilities, protists thrive in aquatic habitats.
The organisms in kingdom fungi include mushrooms, yeasts, molds, rusts, smuts, puffballs, truffles, morels, and molds. More than 70,000 species of fungi have been identified. The fungi constitute and independent group to that of plants and animals. They live everywhere in air, in water, on land, in soil, and on or in plants and animals. Some fungi are microscopic and other extend for more than a thousand acres. Mycology is a discipline of biology which deals with the study of fungi. Fungi appear like plants but are closely related to animals. Fungi are not capable of producing their own food,so they get their nourishment from other sources.
The Plantae includes all land plants: mosses, ferns, conifers, flowering plants, and so on—an amazing range of diverse forms. With more than 250,000 species, they are second in size only to the arthropoda.
Plants have been around for a very long time. The plants first appeared in the Ordovician, but did not begin to resemble modern plants until the Late Silurian. By the close of theDevonian, about 360 million years ago, there were a wide variety of shapes and sizes of plants around, including tiny creeping plants and tall forest trees.
The most striking, and important, feature of plants is their green color, the result of a pigment called chlorophyll. Plants use chlorophyll to capture light energy, which fuels the manufacture of food—sugar, starch, and other carbohydrates. Without these food sources, most life on earth would be impossible. There would still be mushrooms and algae, but there would be no fruits, vegetables, grains, or any animals (which ultimately rely on plants for their food too!)
Another important contribution of plants is their shaping of the environment. Think of a place without plants. The only such places on earth are the arctic wastelands, really arid deserts, and the deep ocean. Everywhere else, from the tundra to the rainforest to the desert, is populated by plants. In fact, when we think of a particular landscape, it is the plants which first come to mind. Try to picture a forest without trees, or a prairie without grasses. It is the plants which produce and maintain the terrestrial environment as we know it.
Kingdom Animalia is one of four kingdoms in the Domain Eukarya. It is distinct from the other three kingdoms, Plantae, Fungi, and Protista, in several ways. Animalia are multicellular, while most Protista (excepting the multicellular algae, which are plant-like) are unicellular. Heterotrophism separates the animals and fungi from plants, and the lack of cell walls in animal cells makes them distinct from fungi. Animals also possess several other unique features. These include interior digestion of food, possession of a digestive tract where hydrolytic enzymes are secreted and digestion takes place, and special cell junctions in their tissues.