（单词翻译:单击）
Junctional epithelium - the epithelium which seals the base of the gingival sulcus against the tooth.
Keratan sulphate - a glycosaminoglycan found in cartilage, with chondroitin sulphate.
Keratin - a fibrous polymer which is notas strong as collagen but less soluble1. It forms the strong and water-resistant properties of skin, nails, hair, horn and beaks2.
Keratinised - an epithelium in which the superficial cells have lost their nuclei3 and become filled with intermediate filaments4 ofkeratin.
Keratinocytes - Cells of the epidermis5 which secrete6 the protein keratin. They become progressively flattened7 as they mature and are eventually are off.
Kreb cycle - the end stage of aerobic8 respiration9. Kreb's cycle is a circular series of reactions taking place in the matrix of mitochondria in which acetyl CoA is broken down into carbon dioxide and hydrogen atoms. The hydrogen atoms are used to produce ATP via the electron transport system.
