Question

DNA polymerases from both prokaryotes and eukaryotes resemble a right hand made up of fingers, palm, and thumb subdomains. True/False

Short answer

True.

Step-by-step solution

Analyze the Statement

We need to determine whether the statement given is true or false. The statement is about the structural resemblance of DNA polymerases from prokaryotes and eukaryotes.

Understanding DNA Polymerase Structure

DNA polymerases are enzymes that synthesize DNA molecules. These enzymes are said to have a structure that is often analogous to a right hand, comprising three main subdomains: fingers, palm, and thumb.

Compare with Known Biological Information

Scientific studies and literature indicate that DNA polymerases from both prokaryotes and eukaryotes do indeed share this common ternary structure of a right hand, with distinct fingers, palm, and thumb domains.

Conclusion from Analysis

Based on the structural understanding of DNA polymerases from both prokaryotic and eukaryotic cells, the statement matches the scientific facts. Therefore, the statement is true.

Key concepts

Prokaryotic DNA Polymerase

Prokaryotic DNA polymerases are essential enzymes found in bacteria and other single-celled organisms. Their primary function is to replicate DNA so that genetic information can be accurately passed down during cell division. The polymerase structure resembles a right hand, consisting of thumb, fingers, and palm subdomains.
This configuration is crucial as each subdomain plays a specific role.

• **Palm Subdomain**: This region is critical for the enzyme's catalytic activity. It holds most of the catalytic residues that add nucleotides to the growing DNA strand.
• **Fingers Subdomain**: It interacts with the incoming nucleotide triphosphates (NTPs) by creating a closed conformation. This ensures that only correctly paired bases are added to the DNA strand.
• **Thumb Subdomain**: Assists in the positioning of DNA and maintains the enzyme's interaction with the DNA substrate.

Prokaryotic DNA polymerases also have some variability depending on their specific types, including differences in processivity and fidelity. However, the overarching hand-like structure remains consistent across these enzymes.

Eukaryotic DNA Polymerase

Eukaryotic DNA polymerases are vital for DNA replication and repair in multi-cellular organisms like plants and animals. Much like their prokaryotic counterparts, eukaryotic DNA polymerases exhibit a structure akin to a right hand.
Their "hand" structure is crucial for their function:

• **Palm Domain**: This area holds the enzyme's active site, which is responsible for catalyzing the addition of nucleotides to the DNA strand. It is involved in the polymerization process and proofreading activities.
• **Fingers Domain**: Facilitates correct base pairing ensuring the integrity of DNA replication by promoting nucleotide incorporation.
• **Thumb Domain**: Engages with the newly synthesized DNA, stabilizing the DNA-enzyme complex and enhancing the enzyme's processivity.

Eukaryotic DNA polymerases are more complex than prokaryotic ones, often having multiple subunits and accessory proteins. This complexity allows them to perform a wider range of functions, including DNA repair and replication of large genomes.

Enzyme Subdomains

The concept of enzyme subdomains is vital in understanding the functionality of DNA polymerases, both in prokaryotes and eukaryotes. The "right-hand" analogy simplifies the visualization of the polymerase's complex architecture.
Each subdomain plays a distinct functional role:

• **Palm Subdomain**: Usually the largest part, responsible for the catalytic activity necessary for DNA synthesis. It also plays a role in proofreading and error correction.
• **Fingers Subdomain**: Engages with nucleotide substrates and guides their correct insertion, thereby ensuring high fidelity in DNA replication.
• **Thumb Subdomain**: Helps in maintaining a stable interaction with the DNA, thus aiding the processivity of the enzyme.

Together, these subdomains allow DNA polymerases to perform their essential roles in the cell, ensuring DNA is replicated accurately and efficiently. This "hand-like" configuration is a beautifully evolved mechanism fitting the intricate demands of DNA synthesis.