Context: Early work in molecular genetics suggested the model that one gene makes one protein. This model has been refined since the discovery of genes that can encode multiple proteins by alternative splicing and coding sequences split in short section across the genome whose mRNAs are concatenated by trans-splicing.

Question: What model did early work in molecular genetics suggest?
Answer: the model that one gene makes one protein.

Question: What discovery caused the model that one gene makes one protein to be refined?
Answer: the discovery of genes that can encode multiple proteins

Question: How do genes encode multiple proteins?
Answer: by alternative splicing and coding sequences

Question: How are alternative splicing and coding sequences distributed?
Answer: split in short section across the genome

Question: In order for a gene to encode multiple proteins, how must its mRNAs be arranged?
Answer: concatenated by trans-splicing.