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ZingPath: Molecular Genetics

DNA Structure

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Molecular Genetics

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Lesson Focus

DNA Structure

Life Science

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Learners explore the structure of DNA as they repair a damaged DNA structure of a black footed ferret.

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Now You Know

After completing this tutorial, you will be able to complete the following:

  • Describe the shape of a DNA molecule as a double helix.
  • Explain that DNA is made up of four types of nucleotides that differ in their bases: adenine, thymine, guanine, and cytosine.
  • Explain that in DNA, adenine binds with thymine, while guanine binds with cytosine.

Everything You'll Have Covered

DNA stands for deoxyribonucleic acid. It is a nucleic acid and the genetic material of living organisms which stores and transmits the genetic information in cells. There are four nucleotides in DNA, frequently called bases. Because of their specific shape and size, nucleotides adenine and thymine always pair together, and nucleotides cytosine and guanine always pair together in a double helix structure. These nucleotide pairs are held together by chemical bonds, called hydrogen bonds, on the DNA. To picture the structure of DNA, imagine a twisted roller coaster track. The pairs of bases, or nucleic acids, are like the cross ties.

Hereditary characteristics are carried on certain parts of the DNA called genes. Each gene controls a hereditary characteristic, and it carries biological information. The genes are located in a region of the DNA that makes up the chromosomes in the nucleus of a cell. Genes can be as short as 1000 base pairs or as long as several hundred thousand base pairs. This variety in gene pairs allows for great diversity among organisms.

DNA is sometimes compared to a blueprint or a recipe for living organisms. It is what dictates human eye color, hair color, and the shape of ears, among other physical characteristics. Human DNA can be found anywhere there are cells that have nuclei including skin, hair follicles, blood, and saliva. DNA testing and profiling is now used to determine family connections. Since it is, in essence, a genetic fingerprint, DNA evidence also can be used to determine if a person was at a crime scene.

The human body contains 10-100 trillion cells, and each human cell contains about 2.5 meters of DNA. If stretched end to end, DNA from a human body would go to the Sun and back to Earth almost seventy times. Another way to think about is this: DNA from a human body would stretch out past the end of our Solar System over four light days.

Tutorial Details

Approximate Time 20 Minutes
Pre-requisite Concepts cells, genes, nucleus
Course Life Science
Type of Tutorial Concept Development
Key Vocabulary adenine, base pairing, base pairs, chemical bonds, chromosomes, cytosine, deoxyribonucleic acid, DNA, double helix, endangered species, genes, genetics, guanine, heredity, inheritance, mutations, nucleic acids, nucleotides, nucleus, radiation, thymine