A retrovirus on injecting its RNA into host cell starts synthesing a single (-)ve strand of DNA which is called

Options

A. cDNA
B. sDNA (synthetic DNA)
C. r-DNA (reverse DNA)
D. reverse RNA

Answer

To solve the question, we need to understand the process by which a retrovirus operates when it infects a host cell. Here’s a step-by-step breakdown:

### Step 1: Understand Retroviruses
Retroviruses are a type of virus that contain RNA as their genetic material. When they infect a host cell, they inject their RNA into that cell.

**Hint:** Retroviruses are characterized by their RNA genome.

### Step 2: RNA to DNA Conversion
Once the retrovirus's RNA is inside the host cell, it needs to convert its RNA into DNA to integrate into the host's genome. This process involves synthesizing a complementary DNA strand.

**Hint:** Retroviruses use a process that involves converting RNA into DNA.

### Step 3: Synthesis of Negative Strand DNA
The retrovirus synthesizes a single negative strand of DNA from its RNA. This newly formed DNA is complementary to the viral RNA.

**Hint:** The DNA synthesized from RNA is called complementary DNA.

### Step 4: Identify the Term for the DNA
The single negative strand of DNA synthesized from the viral RNA is known as complementary DNA, abbreviated as cDNA. This term is used because it is complementary to the original RNA strand.

**Hint:** The term for the DNA synthesized from RNA in retroviruses is cDNA.

### Step 5: Conclusion
Therefore, the answer to the question is that the single negative strand of DNA synthesized by a retrovirus upon injecting its RNA into a host cell is called cDNA.

**Final Answer:** cDNA