Question

the cells within a multicellular organism contain the same set of dna, but two cells might produce a very different set of proteins. how is this possible? cells can have different sets of mrna molecules because different genes are expressed. different cells produce different proteins based on the amino acids they can absorb. ribosomes translate mrna strands differently depending on the type of cell they are in. viral infections can alter the way eukaryotic cells translate their genes into proteins.

Explanation:

• Cellular Differentiation and Gene Expression: In multicellular organisms, cells undergo differentiation. While all cells have the same DNA, different genes are expressed in different cell types. Gene expression involves transcription (DNA to mRNA) and translation (mRNA to protein). When different genes are transcribed (producing different mRNA sets), different proteins are ultimately made.
• Analysis of Options:
• Option 1: Cells having different mRNA sets due to different gene expression is correct. Gene expression regulation (like which genes are "turned on" or transcribed) varies by cell type. For example, a liver cell and a skin cell express different genes, leading to different mRNA and thus different proteins.
• Option 2: Proteins are synthesized based on the genetic code (mRNA sequence) and not directly on the amino - acids a cell can absorb. Amino - acids are the building blocks, but the "recipe" (mRNA from gene expression) determines the protein structure.
• Option 3: Ribosomes use the mRNA sequence (the genetic code) as a template for translation. The basic mechanism of translation (reading the mRNA codons to assemble amino - acids) is highly conserved across cell types. The difference in proteins comes from different mRNA (from different gene expression) not from ribosomes translating mRNA differently based on cell type.
• Option 4: Viral infections are an external, often pathological factor. The normal, physiological reason for different proteins in different cells of a multicellular organism is gene expression (not viral infections, which are an exception rather than the norm for normal cell - to - cell protein differences).

Answer:

The first option "Cells can have different sets of mRNA molecules because different genes are expressed." is correct.