All amino acids have a simple chemical backbone with an amine group (the nitrogen containing part) at one end. At the other end is the acid part. This backbone is the same for all amino acids. The difference between them depends on a distinctive structure, the chemical side chain, that is attached to the backbone. It is the nature of the side chain that gives identity and chemical nature to each amino acid. Twenty amino acids with 20 different side chains make up the proteins of all living tissue.

The amino acids that make up proteins differ from fats and carbohydrates in that they contain the element nitrogen. Proteins differ from each other in the sequence of the amino acids that form a particular chain. They also differ in the way that the protein chain (also called a peptide chain) is linked, coiled, or twisted. (See AMINO ACIDS Transparencies #1 and #2 in Resources.)

Chemically, the backbone of every chain is -C-C-N-. This backbone is also called a peptide chain. If two amino acids join in a chain, it is called a dipeptide. A number of amino acids in a chain are called polypeptide. Molecules of water bind to both the backbone and polar groups of proteins. Polypeptide and proteins are formed from amino acids by a condensation reaction in which one amino acid loses -OH from -COOH and another loses -H from -NH2 to form a peptide bond. Repetition of this reaction (polymerization) converts dipeptide to polypeptide and these in turn to proteins. A strand formula for an amino acid, with the variable group R, has been used in the diagram. Breakdown of proteins to polypeptide to amino acids is the reverse process, an enzyme-catalyzed hydrolysis. (See POLYPEPTIDES AND PROTEINS transparency in Resources.)
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Definition

Glucose is a simple carbohydrate, or sugar. It is very important because cells in an organism use it to provide energy, through respiration. Its chemical formula is C6H12O6

Basics

Glucose (Glc), a monosaccharide (or simple sugar) also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate. Glucose is one of the main products of photosynthesis and starts cellular respiration in both prokaryotes (bacteria and archaea) and eukaryotes (animals, plants, fungi, and protists).

The name “glucose” comes from the Greek word glukus, meaning “sweet”, and the suffix “-ose,” which denotes a sugar.
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This is the 2007 list of atomic weights of the elements, as accepted by the IUPAC. The table is based on the 2005 table at Pure Appl. Chem., 78, 2051-2066 (2006), including the 2007 changes to the atomic weight values for lutetium, molybdenum, nickel, ytterbium and zinc. The elements are listed by increasing atomic number. The number in parenthesis indicates the uncertainty in the last digit of the atomic weight.

Atomic Number – Symbol – Name – Atomic Weight
1 H – Hydrogen – 1.00794(4)
2 He – Helium – 4.002602(2)
3 Li – Lithium – 6.941(2)
4 Be – Beryllium – 9.012182(3)
5 B – Boron – 10.811(7)
6 C – Carbon – 12.0107(8)
7 N – Nitrogen – 14.0067(2)
8 O – Oxygen – 15.9994(3)
9 F – Fluorine – 18.9984032(5)
10 Ne – Neon – 20.1797(6)
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