Number of nucleotides in a DNA double helix

To determine the number of nucleotides in a DNA double helix, we need to understand the structure of DNA and the organization of nucleotides within it.

The structure of DNA

DNA (deoxyribonucleic acid) is a double-stranded molecule that carries the genetic information of an organism. It consists of two strands that are coiled together to form a double helix structure. Each strand is made up of repeating subunits called nucleotides.

Nucleotides

A nucleotide is composed of three components: a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base. There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair with each other to stabilize the DNA double helix: A pairs with T, and C pairs with G.

The length of a DNA double helix

The length of a DNA double helix can be measured in nanometers (nm). In this case, the DNA double helix is 340 nm long.

Calculating the number of nucleotides

To calculate the number of nucleotides in a DNA double helix, we need to know the average length of a nucleotide in DNA. The average length of a nucleotide, including the sugar and phosphate groups, is approximately 0.34 nm.

We can use the following formula to calculate the number of nucleotides:

Number of nucleotides = Length of DNA double helix / Length of a nucleotide

Substituting the given values:

Number of nucleotides = 340 nm / 0.34 nm

Number of nucleotides = 1000

Therefore, the DNA double helix contains approximately 1000 nucleotides.

Summary

- DNA is a double-stranded molecule that carries genetic information.
- Each strand of DNA is made up of repeating subunits called nucleotides.
- Nucleotides consist of a sugar molecule, a phosphate group, and a nitrogenous base.
- The DNA double helix is 340 nm long.
- The average length of a nucleotide in DNA is approximately 0.34 nm.
- To calculate the number of nucleotides, we divide the length of the DNA double helix by the length of a nucleotide.
- The DNA double helix contains approximately 1000 nucleotides.