Question

Indicate whether each of the following occurs on the cytosolic side of the ER membrane (C), on the lumenal side of the ER membrane (L), or in the Golgi apparatus (G). Your answer would be a five-letter string composed of letters C, L, and G only, e.g. GGGLC.

( a ) Assembly of GlcNAc oligosaccharides on dolichol phosphate
( b ) Synthesis of phosphatidylcholine
( c ) Synthesis of sphingomyelin
( d ) Ubiquitylation of misfolded ER protein
( e ) Synthesis of phosphatidic acid

Answer 1

The assembly of GlcNAc oligosaccharides on dolichol phosphate and synthesis of sphingomyelin occur on the lumenal side of the ER membrane, while synthesis of phosphatidylcholine, ubiquitylation of misfolded ER protein, and synthesis of phosphatidic acid occur on the cytosolic side. The correct answer sequence is LCLCC.

Step-by-step explanation:

The endoplasmic reticulum (ER) and the Golgi apparatus are essential components of the eukaryotic cell's endomembrane system, each performing distinct functions. Various molecular synthesis processes occur at different locations within this system. Here's the correspondence for the given processes:

• (a) Assembly of GlcNAc oligosaccharides on dolichol phosphate - Lumenal side of the ER membrane (L)
• (b) Synthesis of phosphatidylcholine - Cytosolic side of the ER membrane (C)
• (c) Synthesis of sphingomyelin - Lumenal side of the ER membrane (L)
• (d) Ubiquitylation of misfolded ER protein - Cytosolic side of the ER membrane (C)
• (e) Synthesis of phosphatidic acid - Cytosolic side of the ER membrane (C)

Therefore, the answer to the student's question would be: LCLCC