During transcription, adenosine forms a base pair with _____ instead of thymine.

Options

A. cytosine
B. uracil
C. any nitrogen base
D. none of these

Answer

To solve the question "During transcription, adenosine forms a base pair with _____ instead of thymine," we can follow these steps:

### Step 1: Understand the Process of Transcription
Transcription is the process where the genetic information from DNA is copied to synthesize RNA. During this process, the DNA strands separate, and one of the strands serves as a template for the synthesis of RNA.

**Hint:** Remember that transcription involves the conversion of DNA to RNA.

### Step 2: Identify the Base Pairing Rules
In DNA, the base pairing rules are as follows:
- Adenine (A) pairs with Thymine (T) through two hydrogen bonds.
- Cytosine (C) pairs with Guanine (G) through three hydrogen bonds.

**Hint:** Recall the base pairing rules in DNA to understand how they change in RNA.

### Step 3: Recognize the Differences in RNA
In RNA, the base Thymine (T) is replaced by Uracil (U). Therefore, during transcription, when adenine (A) from the DNA template strand is present, it will pair with uracil (U) in the RNA strand instead of thymine.

**Hint:** Remember that RNA uses uracil in place of thymine.

### Step 4: Conclusion
Thus, during transcription, adenosine forms a base pair with uracil instead of thymine.

**Final Answer:** Uracil