Question

Which of the following cuts DNA at highly specific target sequences? a. DNA ligase b. DNA polymerase c. restriction enzymes d. RNA polymerase

Short answer

c. restriction enzymes

Step-by-step solution

Understand the Role of Each Enzyme

First, understand what each enzyme does: - DNA ligase is responsible for joining DNA fragments together by forming covalent bonds. - DNA polymerase synthesizes new strands of DNA based on the template strand during DNA replication. - Restriction enzymes cut DNA at specific sequences, typically recognizing palindromic sequences. - RNA polymerase synthesizes RNA from a DNA template.

Identify the Key Function

Note that the question asks for the enzyme that cuts DNA at highly specific target sequences. This implies we need an enzyme that can recognize specific DNA sequences and cut at those points.

Find the Correct Answer

Based on the understanding from Step 1, restriction enzymes are the only ones that match the description of cutting DNA at highly specific target sequences.

Key concepts

DNA Ligase

DNA ligase is a vital enzyme in the replication and repair of DNA. One of its main roles is to join Okazaki fragments on the lagging strand during DNA replication. It achieves this by forming covalent bonds between adjacent nucleotides, essentially 'gluing' DNA fragments together. This process is crucial for maintaining the integrity and continuity of the DNA strand. Without DNA ligase, cells would be unable to effectively replicate their DNA, leading to numerous cellular issues.

DNA Polymerase

DNA polymerase is an enzyme that plays a critical role in DNA replication. It adds nucleotides to the growing DNA strand, using the original strand as a template. This enzyme ensures that the genetic information is accurately copied, allowing cells to divide and reproduce. DNA polymerase also has proofreading abilities to correct any mistakes during the replication process. This safeguards the fidelity of DNA replication and helps prevent mutations.

RNA Polymerase

RNA polymerase is essential for transcribing DNA into RNA. This enzyme binds to a DNA sequence called the promoter and then separates the DNA strands. It uses one of the strands as a template to synthesize a complementary RNA strand. This process is the first step in gene expression, leading to the production of proteins necessary for various cellular functions. RNA polymerase's ability to create RNA from DNA templates is fundamental to the flow of genetic information within a cell.

Enzyme Function

Enzymes are proteins that catalyze biochemical reactions, greatly increasing the rate at which they occur. They function by lowering the activation energy of reactions. Enzymes are highly specific, usually only catalyzing one type of reaction or acting on a specific substrate. This specificity is due to their unique three-dimensional structures, which create an active site perfectly tailored to the substrate. Enzymes play critical roles in processes such as metabolism, DNA replication, and energy production.

DNA Replication

DNA replication is a fundamental process in cell division. During replication, the DNA double helix unwinds, and each strand serves as a template for the creation of a new complementary strand. This process involves several key enzymes, including helicase (which unwinds the DNA), DNA polymerase (which adds nucleotides to the new strand), and DNA ligase (which joins fragments of DNA). DNA replication ensures that each new cell receives an exact copy of the genetic material, preserving genetic continuity.

Restriction Enzymes Specificity

Restriction enzymes are proteins that cut DNA at highly specific sequences, known as restriction sites. These sites are typically palindromic, meaning the sequence reads the same forwards and backwards. Restriction enzymes are vital tools in molecular biology, allowing researchers to cut DNA at precise locations for cloning, gene editing, and DNA analysis. Their ability to recognize and cut specific DNA sequences with such precision makes them invaluable in genetic research and biotechnology.