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  1. Glossary
  2. /Biology
  3. /DNA

What is DNA?

In short

DNA (deoxyribonucleic acid) is the molecule that carries the genetic information of a living thing. It is a double helix made of two strands of nucleotides.

In simple words

Each nucleotide has a sugar (deoxyribose), a phosphate and one of four bases: adenine (A), thymine (T), guanine (G) or cytosine (C). The strands are joined by hydrogen bonds between A and T and between G and C. The order of the bases is the code. A gene is a stretch of DNA that codes for a protein. DNA is copied before a cell divides.

Example

If one strand reads A T G C\text{A T G C}A T G C, the other strand reads T A C G\text{T A C G}T A C G. In a DNA sample with 30%30\%30% adenine, thymine is also 30%30\%30%, and guanine and cytosine are 20%20\%20% each.

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Related terms

  • Mitosis and Meiosis
  • Enzyme

← All glossary terms

Learn it in

  1. DNA as the Genetic Material: Experiments, Structure and PackagingClass 11 to 12
  2. Replication and Transcription: Copying and Reading the GeneClass 11 to 12
  3. The Genetic Code, Translation and Gene RegulationClass 11 to 12
All lessons on this topic →

Practise

  1. A DNA fingerprint of a child has six bands, at 10.2, 6.8, 5.6, 3.3, 2.6 and 1.2 kb…Hard
A cell makes 4 molecules of beta-galactosidase in a minute when no lactose is present…Medium
  • A bacterium has no glucose. Say, for each case, whether the repressor is on the…Medium
  • Here are six events of protein synthesis, in a mixed order…Medium
    • All problems on this topic →

    Quick questions

    1. The DNA fingerprint of a child has 8 bands. Five of them are found in the mother. What…Hard
    2. A gene has a deletion of one base in the middle of its coding region. Another copy has a…Hard
    3. A polypeptide of a bacterium has 330 amino acids. What is the least length, in…Hard

    More Biology terms

    1. Genes and Chromosomes
    2. Algae
    3. Bacteria
    4. Binomial Nomenclature
    5. Cell
    6. Cellular Respiration
    All Biology terms →

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