Question Video: Understanding the Role of DNA Helicase | Nagwa Question Video: Understanding the Role of DNA Helicase | Nagwa

Question Video: Understanding the Role of DNA Helicase Biology • Third Year of Secondary School

In the process of DNA replication, what is the primary role of DNA helicase? [A] DNA helicase detects and repairs any errors that are made by incorrect base pairings during DNA replication. [B] DNA helicase breaks the hydrogen bonds between base pairs, separating the two strands of DNA. [C] DNA helicase forms phosphodiester bonds between nucleotides to form a strand of DNA. [D] DNA helicase adds nucleotides to a growing DNA chain, synthesizing a strand of DNA complementary to the template strand. [E] DNA helicase joins the gaps in the backbone between newly formed DNA fragments.

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Video Transcript

In the process of DNA replication, what is the primary role of DNA helicase? (A) DNA helicase detects and repairs any errors that are made by incorrect base pairings during DNA replication. (B) DNA helicase breaks the hydrogen bonds between base pairs, separating the two strands of DNA. (C) DNA helicase forms phosphodiester bonds between nucleotides to form a strand of DNA. (D) DNA helicase adds nucleotides to a growing DNA chain, synthesizing a strand of DNA complementary to the template strand. Or (E) DNA helicase joins the gaps in the backbone between newly formed DNA fragments.

This question is asking us what the primary role of the enzyme DNA helicase is during DNA replication. To answer this, let’s first clear the answer choices so we have more room to work with. In order for a cell to divide and make a new cell, its DNA must first be copied or replicated to form a new molecule of DNA. You’ll recall that DNA is a double-stranded helix. These colored boxes that you see are the different nucleotides that make up the DNA molecule.

Let’s zoom in here so we can take a closer look. Here, we can see the two strands of DNA. DNA is made up of repeating subunits called nucleotides. Each nucleotide contains a phosphate group, a deoxyribose sugar, and a nitrogenous base. In DNA, there’s four types of nitrogenous bases: guanine, cytosine, adenine, and thymine. The sequence of these nitrogenous bases along these strands of DNA can code for different genes. These bases form base pairs because complementary bases can hydrogen-bond with each other. Guanine always pairs with cytosine and forms three hydrogen bonds, while adenine always pairs with thymine and forms two hydrogen bonds. These hydrogen bonds between these bases are what hold these two strands of DNA together.

In order for DNA replication to occur, these two strands need to be separated so the DNA can be copied. The enzyme that breaks these hydrogen bonds and separates the two strands is called DNA helicase. Therefore, in the process of DNA replication, the primary role of DNA helicase is to break the hydrogen bonds between base pairs separating the two strands of DNA.

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