Question

where are proteins assembled (put together) in a cell?
nucleus
cell membrane
ribosome
muscles

Explanation:

Ribosomes are the cellular structures responsible for protein synthesis. They read the genetic information (mRNA) and assemble amino acids into proteins. The nucleus contains DNA but does not directly assemble proteins. The cell membrane is involved in protecting the cell and regulating what enters and exits. Muscles are tissues made up of cells and are not a cellular structure where proteins are assembled.

Answer:

Ribosome