Question

What would happen to the replication process if the growing DNA chain did not have a free 3 ' end?

Short answer

The replication process would halt because DNA polymerase cannot add new nucleotides without a free 3' end.

Step-by-step solution

Understanding the Role of the 3' End

The 3' end of the DNA strand contains a hydroxyl group (-OH) that is crucial for the addition of new nucleotides. DNA polymerases, the enzymes responsible for synthesizing DNA, can only add nucleotides to this free 3' hydroxyl group.

DNA Polymerase Action

DNA polymerase extends the DNA strand by adding nucleotides to the 3' end. It catalyzes the formation of a phosphodiester bond between the 3' hydroxyl group of the growing strand and the 5' phosphate group of the incoming nucleotide.

Implication of No Free 3' End

Without a free 3' end, DNA polymerase would have no position to add new nucleotides. This would halt the elongation of the new DNA strand and, consequently, stop the replication process.

Key concepts

3' end

The 3' end of a DNA strand is crucial in DNA replication. It refers to the third carbon in the sugar ring of a DNA nucleotide to which a hydroxyl group (-OH) is attached. This hydroxyl group is essential because DNA polymerases can only add new nucleotides here.

DNA polymerase

DNA polymerase is an enzyme that synthesizes DNA molecules. It plays a vital role in DNA replication by adding nucleotides to the growing DNA strand. DNA polymerase works by beginning at the 3' end, where it reads the template strand and adds complementary nucleotides to form a new strand.

nucleotides

Nucleotides are the building blocks of DNA. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base. During DNA replication, these nucleotides pair up with their complementary bases on the template strand. DNA polymerase links them together, forming a new DNA strand.

phosphodiester bond

A phosphodiester bond is a covalent bond that links nucleotides together in a DNA strand. It forms between the 3' hydroxyl group of one nucleotide and the 5' phosphate group of the next. This bond is essential for the structural integrity of DNA. DNA polymerase catalyzes the formation of these bonds during DNA replication, ensuring the new strand is stable and continuous.