**Question:** Primase activity is present in

A. DNA polymerase α
B. DNA polymerase δ
C. DNA polymerase ε
D. DNA polymerase γ

**Core Concept:** Primase is an enzyme involved in DNA replication, responsible for synthesizing short, singlestranded RNA primers that serve as a starting point for DNA polymerase to synthesize the complementary DNA strand. Primase activity is essential for the initiation of DNA replication in prokaryotic and eukaryotic cells.

**Why the Correct Answer is Right:** Primase activity is associated with DNA polymerase α, which is a component of the replicative DNA polymerase holoenzyme in eukaryotes. Primase forms RNA primers by catalyzing the synthesis of short, single-stranded RNA nucleotides complementary to the DNA template strand. This primer is then extended by DNA polymerase to synthesize the complementary DNA strand.

**Why Each Wrong Option is Incorrect:**

A. DNA polymerase α contains primase activity, making it the correct answer.
B. DNA polymerase δ is involved in DNA replication but does not have primase activity; it primarily synthesizes the lagging strand.
C. DNA polymerase ε is involved in DNA replication but does not have primase activity; it primarily synthesizes the leading strand.
D. DNA polymerase γ is involved in DNA replication but does not have primase activity; it primarily synthesizes the lagging strand in mitochondria and chloroplasts.

**Clinical Pearl:** Understanding primase activity and its association with DNA polymerase α is crucial for understanding DNA replication processes in eukaryotic cells and their implications in genetic disorders like Bloom syndrome, Werner syndrome, and ataxia telangiectasia. These genetic disorders are caused by mutations in the genes encoding DNA polymerase α, resulting in impaired DNA replication and genomic instability.

**Correct Answer:** D. DNA polymerase γ