<prompt> Which of the following substances is primarily found in tendons?CollagenFibrinFibrillinProtedglycans  <response>: Ans. is a i.e., Collagen o Tendon is primarily made up of collagen.o Main component of connective tissue. Most abundant protein in mammals.Major collagen typesTypeTissue distributionIIIVBone, dermis, tendon, ligament corneaCartilage, vitreous body, nucleus pulposusSkin, vessel wall, reticular fibres of most tissues lung, liver, spleen etcLung, cornea, bone, fetal membranes together with type I collagenSome key points about collageno Protein makes up about 20 of the bodys mass and collagen makes up around 30 of the protein in the human body.o There are at least 16 types of collagen but 80-90 of collagen in the body consists of type I, II and III.Characterizations of collageno The various isoforms are the most abundant proteins in the animal kingdomo There are at least 16 types or 24 typeso Types I, II and III are the most abundant and form fibrilso Type IV forms sheets found in the basal laminao They form triple heliceso They have unique segments that interrupt the triple helix and are responsible for the unique properties of individual collageno They contain a three residue repeat of: glycine, proline, Xo They are rich n hydroxyprolineo There are three amino acids per turn of the helix, with pyrrolidone rings on the outside of the helixo The helix is stabilized by hydrogen bondso The fibrous backbone of the extracellular matrix 