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A disaccharide (also called a double sugar or biose) [1] is the sugar formed when two monosaccharides are joined by glycosidic linkage. [2] Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, lactose, and maltose. Disaccharides are one of the four chemical groupings of carbohydrates ...
Deoxyribonucleic acid (DNA) is a nucleic acid containing the genetic instructions used in the development and functioning of all known living organisms. The chemical DNA was discovered in 1869, but its role in genetic inheritance was not demonstrated until 1943. The DNA segments that carry this genetic information are called genes.
Monosaccharides can be classified by the number x of carbon atoms they contain: triose (3), tetrose (4), pentose (5), hexose (6), heptose (7), and so on. Glucose, used as an energy source and for the synthesis of starch, glycogen and cellulose, is a hexose .
Each deoxyribonucleotide comprises three parts: a deoxyribose sugar (monosaccharide), a nitrogenous base, and one phosphoryl group. [1] The nitrogenous bases are either purines or pyrimidines , heterocycles whose structures support the specific base-pairing interactions that allow nucleic acids to carry information.
In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand. The secondary structure is responsible for the shape that the nucleic acid assumes. The bases in the DNA are classified as purines and pyrimidines. The purines are adenine and guanine ...
Most DNA molecules are actually two polymer strands, bound together in a helical fashion by noncovalent bonds; this double-stranded (dsDNA) structure is maintained largely by the intrastrand base stacking interactions, which are strongest for G,C stacks. The two strands can come apart—a process known as melting—to form two single-stranded ...
[2] Both types of pentoses in DNA and RNA are in their β-furanose (closed five-membered ring) form and they define the identity of a nucleic acid. DNA is defined by containing 2'-deoxy-ribose nucleic acid while RNA is defined by containing ribose nucleic acid. [1] In some occasions, DNA and RNA may contain some minor bases.
Kinetochores start, control, and supervise the striking movements of chromosomes during cell division. During mitosis, which occurs after the amount of DNA is doubled in each chromosome (while maintaining the same number of chromosomes) in S phase, two sister chromatids are held together by a centromere. Each chromatid has its own kinetochore ...