Final answer:
In a pulse-chase experiment with a short chase time, the first appearance of labelled proteins will be on ribosomes, followed by a move to the endoplasmic reticulum and then to the Golgi apparatus for modification and tagging.
Step-by-step explanation:
The first appearance of labelled protein in a pulse-chase experiment with a short chase time would be in the ribosomes. Ribosomes are responsible for the synthesis of proteins, where amino acids are assembled into polypeptides based on the sequence of an mRNA template. After a short chase period, these newly synthesized proteins would then move to be processed in the endoplasmic reticulum, where they would undergo modification. If they are to be secreted from the cell or sent to an organelle, they would next be tagged in the Golgi apparatus before being distributed in vesicles to their final destinations.