Video segment. Assistance may be required. Click the Next button to watch the following presentation and learn more about the structure of DNA.

Take out a piece of paper to respond to the questions below.

  1. What is the basic structure of DNA?

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    The basic structure of DNA is a double helix, or twisted ladder.Close Pop Up

  2. What are the building blocks of DNA?

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    The building blocks of DNA are nucleotides.Close Pop Up

  3. What are the parts of a nucleotide?

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    The parts of a nucleotide include the following: phosphate group, deoxyribose sugar, and a nitrogen base.Close Pop Up

  4. The sides of the DNA ladder are made up of what two alternating molecules?

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    The two sides of the DNA ladder are made up of phosphate and deoxyribose sugar.Close Pop Up

  5. What does it mean to have antiparallel strands?

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    When DNA has antiparallel strands is means that the different strands in the helix run in opposite (anti-parallel) directions. At each end of the double helix, one strand is 5', and the other is 3'. Close Pop Up

  6. What makes up the steps or rungs of the ladder?

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    Nitrogen bases makes up the steps or rungs of the DNA ladder. Close Pop Up

  7. What is special about the order of the nitrogen bases?

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    It is the order of the nitrogen bases that carries the human genetic code.Close Pop Up

  8. What are the four nitrogen bases?

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    The four nitrogen bases include the following: adenine, thymine, guanine and cytosine.Close Pop Up

  9. According to the base pairing rules, adenine always pairs with __________.

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    thymineClose Pop Up

  10. What type of bond holds the nitrogen bases together?

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    A weak hydrogen bond holds the nitrogen bases together.Close Pop Up