User:Jmcain58/sandbox

Peer Review: by mkuck23

I was going to say you should put more emphazise on the Imoportance and Uses section but it appears below that you haveYou also might want to inlude a diagram for the Life Cycle portion to help users summarize it. .I

ouldwalso suggest that you include more on the asexual reproduction to clarify the difference between the two. In the Life Cycle section for someone who hasn't learned about this before it is confusing as to which things refer to sexual vs asexual reproduction. You also could alwyas add more to the symbiotic relationship mentioned in the introduction.

Brown Algae

The Phaeophyceae or brown algae (singular: alga), are a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters. They play an important role in marine environments, both as food and for the habitats they form. For instance, Macrocystis, a kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater forests. Forests like these contain a high level of biodiversity. Another example is Sargassum, which creates unique habitats in the tropical waters of the Sargasso Sea. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Some members of the class, such as kelp, are used as food for humans.

Worldwide, over 1500–2000 species of brown algae are known. Some species, such as Ascophyllum nodosum, are of sufficient commercial importance because they have become subjects of extensive research in their own right. They have environmental importance too through Carbon fixation. In the ecosystem, there is sometimes a symbiostic relationship between coral and algae. Coral will host algae and use its carbon fixation for it own good. This relationship isn't always mutually beneficial, as the coral often loses its pigments and begins bleaching.

Brown algae belong to a very large group, the Heterokontophyta, a group of eukaryotic organisms distinguished most prominently by having chloroplasts surrounded by four membranes, suggesting an origin from a symbiotic relationship between a basal eukaryote and another eukaryotic organism. Most brown algae contain the pigment fucoxanthin, which is responsible for the distinctive greenish-brown color that gives them their name. Brown algae are unique among heterokonts in developing into multicellular forms with differentiated tissues, but they reproduce by means of flagellated spores and gametes that closely resemble cells of other heterokonts. Genetic studies show their closest relatives to be the yellow-green algae. They're unique because they have evolutionary history that ties them back with not only plants but also fungi and animals.

Life Cycle

Most brown algae, with the exception of the Fucales, perform sexual reproduction through sporic meiosis. Between generations, the algae goes through separate diploid and haploid phases. Free floating brown algae do not undergo sexual reproduction until they attach themselves to substrate. The haploid generation is made of male and female gametophyte. The fertilization of egg cells varies between species of brown algae, and may be isogamous, oogamous, or anisogamous.  Union of gametes may take place in water between eggs and motile sperm, or within the oogonium itself. All species of brown algae can also perform asexual reproduction through the production of diploid zoospores.

In a representative species Laminaria, there is a conspicuous diploid generation and smaller haploid generations. Meiosis takes place within several sporangium along the algae's blade, forming haploid male and female zoospores. The spores are then released from the sporangia and grow to form male and female gametophyes. The female gametophyte produces an egg in the oogonium, and the male gametophyte releases motile sperm that fertilize the egg. The fertilized zygote then grows into the mature diploid sporophyte.

In the order Fucales, sexual reproduction is oogamous, and the mature diploid is the only form for each generation. Gametes are formed in specialized conceptacles along the blades of the parent plant. Egg cells and motile sperm are released from separate sacs on the parent algae, combining in the water to complete the fertilization. The fertilized zygote then differentiates into a leafy thallus and a holdfast upon fixing itself to substrate,

Importance and Uses

Brown algae include a number of edible seaweeds, and a number of brown algae contains alginic acid that is extracted commercially and used in a large number of products. One of these products in a Lithium Ion battery. Alginic acid is extracted from the cell wall of brown algae and is a stable component of a battery anode. This Polysaccharide is not found in many land plants yet is a major component of brown algae.

Alginic acid can also be used in Aquaculture. Rainbow trout have enhanced immune system when they are exposed to alginic acid. Younger fish are more likely to survive when given a diet with alginic acid.

Brown algae including kelp beds also provide the planent with carbon dioxide fixation through photosynthesis. The conversion of carbon dioxide to oxygen is not only performed by photosynthesizing land plant, but also by algae that perform photosynthesis.

Sargachromanol G, found in brown algae, may be anti-inflammatory. Crossed with other polymers and amino acids, properties that indicate anti-swelling characteristics have been found.