Which phenomenon made it possible to produce animal proteins in plants through rDNA technology?

Options

A. The human chromosome can replicate in bacteria.
B. The mechanism of gene regulation is identical in humans and bacteria
C. Bacterial cell can carry out the RNA splicing reaction
D. The genetic code is universal

Answer

To solve the question regarding the phenomenon that enables the production of animal proteins in plants through recombinant DNA (rDNA) technology, we can analyze the provided options step by step:

### Step-by-Step Solution:

1. **Understanding rDNA Technology**:
- rDNA technology involves combining DNA from different sources to create a new genetic combination. This technology allows for the introduction of genes from one organism into another, enabling the expression of specific proteins.

2. **Evaluating the Options**:
- **Option 1: Human chromosome can replicate in bacteria**:
- This statement is incorrect. Human chromosomes are complex and cannot replicate in bacteria due to differences in cellular structures and mechanisms.

- **Option 2: Mechanism of gene regulation is identical in humans and bacteria**:
- This statement is also incorrect. While there are similarities, the mechanisms of gene regulation differ significantly between prokaryotes (like bacteria) and eukaryotes (like humans).

- **Option 3: Bacterial cell can carry out the RNA splicing reaction**:
- This is incorrect as well. Bacteria do not have the machinery for RNA splicing, which is a process that occurs in eukaryotic cells.

- **Option 4: The genetic code is universal**:
- This statement is correct. The genetic code is nearly universal, meaning that the same codons specify the same amino acids across different organisms, including plants and animals. For example, the codon AUG codes for methionine in both humans and bacteria.

3. **Conclusion**:
- Based on the analysis, the phenomenon that makes it possible to produce animal proteins in plants through rDNA technology is that the genetic code is universal. Thus, the correct answer is **Option 4**.

### Final Answer:
The correct option is **the genetic code is universal**.