ABSTRACT
Proteins ar e larg e molecule s tha t pla y a vita l rol e i n th e organizatio n an d
function o f l ivin g organisms . The y ar e polymers o f amin o acids , a n d thei r size s
range fro m a fe w thousan d t o th e ten s o f million s o f daltons . A m o n g th e mor e
important function s performe d b y protein s ar e th e following . (1 ) T h e y provid e
the structura l framewor k o f cell s an d tissues . Example s ar e collage n an d
elastin. (2 ) The y ac t a s antibodie s i n th e bloodstrea m t o immobiliz e foreig n
materials, suc h a s viruse s an d bacteria . (3 ) The y ac t a s biologi c catalysts , calle d
enzymes. (4 ) The y perfor m mechanica l work , suc h a s skeleta l muscl e contrac -
tion an d th e pumpin g actio n o f th e heart . (5 ) The y ac t a s transpor t media i n th e
bloodstream fo r a variety of substances , suc h a s lipid s an d oxygen .
