Nucleus in plant cells

Within its cell wall and membrane, a plant cell has two basic parts called the nucleus and the cytoplasm. The cell nucleus contains tiny threads called chromosomes.

Chromosomes carry the plant’s genes, the basic units of heredity. The first description of a subcellular structure termed “the nucleus” can be found in a paper first delivered to the Linnean Society of London on November of 1831.

The shape of the nucleus may be related to that of the cells or may be completely irregular. In spheroidal, cuboidal or polyhedral cells, the nucleus is generally a spheroid. In cylindrical, prismatic, or fusiform cells, it tends to be an ellipsoid.

The nucleus occupies about 10% of a eukaryotic cell’s volume, In general, each somatic nucleus has a specific size that depends partly on its, DNA content and mainly on its protein content and so its size is related to functional activity during the period of nondivision.

Nucleus serves two important functions. First, it keeps the cell’s genetic material – its DNA – safe and sound. Isolated in its own compartment, the cell’s DNA stays separated from the bustling activity of the cytoplasm and from metabolic processes that might damage it.
Nucleus in plant cells

Classification of Wheat

Classification of Wheat
Wheat belongs to the grass family, Gramineae, and the genus Triticum. The known species and varieties of the genus Triticum are said to number over 30,000. They can be assembles into three groups (races), which are traced from separate original ancestors and which differ in their number of chromosomes.

The classification suggests a possible explanation for differences in the flour from three wheat groups. Einkorn (T. monococcum) is used only as an animal feed. Emmer wheats are used for macaroni, spaghetti, and other pasta products, and not for breadmaking. Wheat from the spelt group is used in baked goods and other cereal products. The principle wheats of commerce are Triticum aestivum, Triticum compactum, both in the spelt group and Triticum durum, in the Emmer group.

In addition to their classification into groups based on chromosome number, wheats are classified as hard or soft referring to milling character and strong or weak.

The terms hard and soft wheat relate to the way the endosperm break during milling. In hard wheats, the endosperm tends to fracture along the lines of the cell boundaries, whereas in soft wheats the endosperm fractures in a random ways. Hard wheats yield coarse flour, consisting of regular-shaped particles, which is free flowing and easily sifted. In contrast, the flour from soft wheats is very fine and consists of irregularly-shaped particles, which tend to adhere together; such flour sifts with some difficulty.

Strength is a characteristic of wheat associated with the ability of its flour to produce bread of large loaf volume, good crumb texture and good keeping qualities. Strong wheats as a rule have a high protein content, whereas weak wheats have low protein contents. The flour from a weak wheat produces bread of small loaf volume, coarse crumb structure, and low protein content. Thus protein content is related to baking characteristics.
Classification of Wheat