Answer:
Cytochrome C is a protein found in the mitochondria of all eukaryotic cells that plays a vital role in the process of cellular respiration. By comparing the amino acid sequence of cytochrome C between different species, scientists can infer information about their evolutionary relationships.
The number of amino acid differences between cytochrome C in different species indicates the amount of time that has passed since those species diverged from a common ancestor. The more amino acid differences there are between two species, the longer ago they diverged from a common ancestor.
For example, the cytochrome C sequences of a rat and a fruit fly differ by around 50 amino acids, indicating that they diverged from a common ancestor around 800 million years ago. On the other hand, the cytochrome C sequences of a human and a yeast cell differ by around 150 amino acids, indicating that they diverged from a common ancestor around 1.5 billion years ago.
Overall, cytochrome C sequencing can provide important information about the evolutionary history of different species and can help us understand how they are related to each other.