Paper 2 · Cell Structure and Membranes
Fig. 1.1 is a diagram of a typical mammalian cell. The structure labelled A is the
AGolgi apparatus, which modifies and packages proteins for secretion
Brough endoplasmic reticulum, which assembles amino acids into polypeptides
Csmooth endoplasmic reticulum, which synthesises and transports lipids
Dlysosome, which stores hydrolytic enzymes until worn out organelles are digested
Explanation: A is a stack of flattened membrane sacs with vesicles budding from its edges, which is the Golgi apparatus. Proteins arriving from the endoplasmic reticulum are chemically modified there, often by adding sugars, and are then pinched off in vesicles for secretion.
Derived from ZIMSEC Biology Paper 2, Nov 2003, Q1