Final answer:
Two cellular characteristics supporting the idea of common ancestry are the universal genetic code and common cellular structures like the cell membrane and ribosomes. These features, widely present across all life forms, point to a last universal common ancestor.
Step-by-step explanation:
Researchers believe that all organisms on Earth share a common ancestor, and there are several cellular characteristics that support this claim. Two of these characteristics are:
- Universal Genetic Code: All cells contain DNA that utilizes the same four nucleotide bases to store genetic information. This universal genetic code is a powerful piece of evidence for common ancestry, as it suggests that all life evolved from an organism that used that same genetic system.
- Cellular Structures: Despite the vast diversity of life, there are common cellular structures shared across all domains of life, such as a cell membrane, ribosomes, and to some extent, the use of RNA and DNA as genetic materials. In particular, the presence of a cell membrane and ribosomes, which are crucial for protein synthesis, in all cells points to a common ancestral cell from which all current cells derive.
These shared characteristics not only indicate a common ancestry but also highlight the effectiveness of these cellular components in sustaining and propagating life. Francis Crick, one of the discoverers of the DNA structure, referred to the flow of information from DNA to RNA to protein as the Central Dogma of molecular biology, further evidencing the fundamental role of these processes in all living organisms.