Question Video: Identifying the Components of DNA | Nagwa Question Video: Identifying the Components of DNA | Nagwa

Question Video: Identifying the Components of DNA Biology • Third Year of Secondary School

Join Nagwa Classes

Attend live Biology sessions on Nagwa Classes to learn more about this topic from an expert teacher!

A simple diagram of the structure of DNA is provided. What part of this structure is indicated by label X?

01:27

Video Transcript

A simple diagram of the structure of DNA is provided. What part of this structure is indicated by label X?

You’re probably familiar with the double-stranded helix structure of DNA. An untwisted representation of the molecule is shown here. You could see the two strands indicated here. Each strand is made up of repeating subunits called nucleotides. A single nucleotide is made up of three different parts: a phosphate group, a deoxyribose sugar, and a nitrogenous base. There are four different bases in DNA: guanine, represented in orange; cytosine, represented in blue; adenine, represented in green; and thymine, represented in pink.

As you can see here, the two nitrogenous bases can form hydrogen bonds with each other and pair up. This is how the two strands are held together. Each nucleotide is attached to the next by a phosphodiester bond. Through this phosphodiester bond, a phosphate group of one nucleotide is bonded to the sugar group of the next. This forms the sugar–phosphate backbone of one strand.

Therefore, the part of this diagram that is labeled as X is the sugar–phosphate backbone.

Join Nagwa Classes

Attend live sessions on Nagwa Classes to boost your learning with guidance and advice from an expert teacher!

  • Interactive Sessions
  • Chat & Messaging
  • Realistic Exam Questions

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy