Organisms are classified into three distinct domains: Archaea, Bacteria, and Eukarya.
To determine the evolutionary relationships among these groups, biologists analyzed a variety of molecular, genetic, and structural characteristics.
The table below summarizes several cellular and biochemical features of the three domains:
| Feature | Bacteria | Archaea | Eukarya |
|---|---|---|---|
| DNA associated with histones | Absent | Present in some | Present |
| Initiator tRNA amino acid | Formyl-methionine | Methionine | Methionine |
| Cytosolic ribosome size | 70S | 70S | 80S |
| Sensitivity to chloramphenicol | Sensitive | Insensitive | Insensitive |
| RNA polymerase promoter structure | Lacks TATA-like consensus | TATA-like consensus present | TATA-like consensus present |
Explain what conclusions can be drawn from the table about which domains are most closely related.
State the cellular roles of ribosomes and histones.
22 exam-style questions on OCR A A Level Biology Classification and evolution. Each one has a worked solution and a mark scheme showing where the marks go.