Final answer:
The statement 'Fatty acid synthase can generate 20-carbon fatty acids' is false because fatty acid synthase (FAS) synthesizes fatty acids up to 16 carbons. Longer fatty acids are formed by separate enzymes called elongases in the endoplasmic reticulum and mitochondria.
Step-by-step explanation:
Fatty acid synthase (FAS) in eukaryotes, often a large enzyme complex, is primarily responsible for the synthesis of saturated fatty acids up to 16 carbons in length, a process that ends with the production of palmitate (palmitoyl-ACP). This complex, arranged as a dimer, adds carbons in two-carbon increments using the malonyl-CoA molecule as a substrate.
Further elongation beyond 16 carbons to form longer fatty acids, such as 20-carbon fatty acids, occurs in the endoplasmic reticulum and mitochondria and is carried out by separate enzymes known as elongases. These processes are similar in that they use a malonyl group to add two carbons, but CoA is attached to the intermediates, not ACP like in the FAS complex.