Search results
Results from the WOW.Com Content Network
Structure of a typical L-alpha-amino acid in the "neutral" form. Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. [1] Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. [2] Only these 22 appear in the genetic code of life ...
A life form (also spelled life-form or lifeform) is an entity that is living, [1] [2] such as plants , animals , and fungi . It is estimated that more than 99% of all species that ever existed on Earth, amounting to over five billion species, [3] are extinct. [4] [5] Earth is the only celestial body known to harbor life forms. No form of ...
The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope.
Essential amino acid. An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life forms, the nine amino acids humans cannot synthesize are valine, isoleucine ...
Amino acid 6-17 × 10 −6: 1.3-3.6 × 10 −5: Arsenic: normal range 2-62 × 10 −9: chronic poisoning 100-500 × 10 −9: acute poisoning 600-9300 × 10 −9: Ascorbic acid (Vitamin C) Important vitamin 1-15 × 10 −6: 6-20 × 10 −6: Aspartic acid: Amino acid 0-3 × 10 −6: In WBCs 2.5-4.0 × 10 −4: 9-12 × 10 −6: Bicarbonate: Buffer ...
Primordial life "discovered" new amino acids (for example, as by-products of metabolism) and later incorporated some of these into the machinery of genetic coding. [95] Although much circumstantial evidence has been found to suggest that fewer amino acid types were used in the past, [ 96 ] precise and detailed hypotheses about which amino acids ...
A protein is a polyamide. Secondary structure: regularly repeating local structures stabilized by hydrogen bonds. The most common examples are the α-helix, β-sheet and turns. Because secondary structures are local, many regions of different secondary structure can be present in the same protein molecule.
Human anatomy is the study of the shape and form of the human body. The human body has four limbs (two arms and two legs), a head and a neck, which connect to the torso. The body's shape is determined by a strong skeleton made of bone and cartilage, surrounded by fat (adipose tissue), muscle, connective tissue, organs, and other structures.