State the role of deoxyribonucleoside triphosphates during DNA replication

Options

A. They are the building blocks for the DNA-strand.
B. They serve as energy source in the form of ATP.
C. They serve as energy source in the form of GTP.
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding Deoxyribonucleoside Triphosphates (dNTPs):**
- Deoxyribonucleoside triphosphates (dNTPs) are the building blocks of DNA. They include deoxyadenosine triphosphate (dATP), deoxycytidine triphosphate (dCTP), deoxyguanosine triphosphate (dGTP), and deoxythymidine triphosphate (dTTP).

2. **Role as Building Blocks:**
- During DNA replication, dNTPs are incorporated into the growing DNA strand. Each dNTP consists of a nitrogenous base, a deoxyribose sugar, and three phosphate groups. The sequence of these bases determines the genetic information in the DNA.

3. **Energy Source:**
- The triphosphate groups in dNTPs provide energy for the polymerization process. When a dNTP is added to the growing DNA strand, two phosphate groups are released as pyrophosphate (PPi), which releases energy that drives the formation of the phosphodiester bond between nucleotides.

4. **Involvement in DNA Synthesis:**
- DNA polymerase, the enzyme responsible for DNA synthesis, utilizes dNTPs to add nucleotides to the 3' end of the growing DNA strand. This process occurs in a 5' to 3' direction.

5. **Priming DNA Synthesis:**
- Although dNTPs are not primers themselves, they are essential for the elongation of the DNA strand initiated by a short RNA primer. The RNA primer provides a free 3' hydroxyl group for the first dNTP to attach.

**Final Summary:**
Deoxyribonucleoside triphosphates (dNTPs) play a crucial role in DNA replication as the building blocks of DNA, providing the necessary energy for the polymerization process, and serving as substrates for DNA synthesis.

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