Removal of introns and joining the exons in a defined order in a transcription unit is

Options

A. Transformation
B. Capping
C. Splicing
D. Tailing

Answer

To solve the question, "Removal of introns and joining the exons in a defined order in a transcription unit is," we will analyze the options provided and identify the correct answer step by step.

### Step-by-Step Solution:

1. **Understand the Question**: The question is asking about a specific process that involves the removal of introns (non-coding regions) and the joining of exons (coding regions) in a transcription unit.

2. **Examine the Options**:
- **Transformation**: This is a process related to genetic recombination in bacteria where they take up foreign DNA from their environment. It is not related to RNA processing.
- **Capping**: This refers to the addition of a modified guanine nucleotide at the 5' end of the mRNA. While it is an important modification, it does not involve the removal of introns or the joining of exons.
- **Splicing**: This is the process where introns are removed from the precursor mRNA and exons are joined together to form mature mRNA. This process occurs in the nucleus and is facilitated by a complex known as the spliceosome.
- **Tailing**: This involves the addition of a poly-A tail at the 3' end of the mRNA. It helps stabilize the mRNA and is not related to the removal of introns.

3. **Identify the Correct Answer**: Based on the analysis, splicing is the process that specifically involves the removal of introns and the joining of exons. Therefore, the correct answer is **Splicing**.

### Final Answer:
The removal of introns and joining the exons in a defined order in a transcription unit is **Splicing**.