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An endosperm is formed after the two sperm nuclei inside a pollen grain reach the interior of a female gametophyte or megagametophyte, also called the embryonic sac.One sperm nucleus fertilizes the egg cell, forming a zygote, while the other sperm nucleus usually fuses with the binucleate central cell, forming a primary endosperm cell (its nucleus is often called the triple fusion nucleus).
This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws, diagrams and formulae, laboratory tools, glassware, and equipment. Chemistry is a physical science concerned with the composition, structure, and properties of matter , as well as the changes it undergoes during chemical reactions ...
Usually in germination, the breakdown of starch to glucose in the endosperm begins shortly after the seed is exposed to water. [10] Gibberellins in the seed embryo are believed to signal starch hydrolysis through inducing the synthesis of the enzyme α- amylase in the aleurone cells.
After entering an ovule through the micropyle, one male nucleus fuses with the polar bodies to produce the endosperm tissues, while the other fuses with the egg cell to produce the embryo. [3] [4] Hence the term: "double fertilisation". This process would result in the production of a seed, made of both nutritious tissues and embryo.
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A refined grain is defined as having undergone a process that removes the bran, germ and husk of the grain and leaves the endosperm, or starchy interior. [1] Examples of refined grains include white bread, white flour, corn grits and white rice. [2] Refined grains are milled which gives a finer texture and improved shelf life. [3]
The endosperm is surrounded by the aleurone layer (peripheral endosperm), filled with proteinaceous aleurone grains. Originally, by analogy with the animal ovum, the outer nucellus layer was referred to as albumen, and the inner endosperm layer as vitellus. Although misleading, the term began to be applied to all the nutrient matter.
While the sperm develops inside of the male testes, the sperm does not become a pronucleus until it decondenses quickly inside of the female egg. [3] When the sperm reaches the female egg, the sperm loses its outside membrane as well as its tail. The sperm does this because the membrane and the tail are no longer needed by the female ovum.