Why might a group of rats being fed gelatin as their sole protein source fail to grow well?

Gelatin is derived from collagen and is predominantly composed of amino acids, but it is notably deficient in certain essential amino acids necessary for growth and overall health. The correct answer emphasizes that gelatin lacks tryptophan and has low levels of methionine and lysine.

Tryptophan is an essential amino acid that plays a crucial role in protein synthesis and is a precursor for serotonin, which regulates mood and behavior. Methionine is also an essential amino acid that is important for various metabolic functions and acts as a precursor of other important compounds, including cysteine. Lysine is vital for protein synthesis and plays a key role in calcium absorption, muscle protein synthesis, and the production of hormones and enzymes.

When these amino acids are insufficient, as is the case with gelatin as a sole protein source, the rats may be unable to promote adequate growth because their dietary needs are not fully met. Lacking these essential amino acids can lead to stunted growth and other health issues, demonstrating the importance of consuming a balanced diet that contains a complete set of essential amino acids. Thus, the combination of deficiencies in tryptophan, methionine, and lysine in gelatin accounts for the potential failure of the rats to thrive when fed exclusively