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Genetics

DNA structure, genes and the genome

  • 3 things to know
  • Paper 1

Overview

DNA as a double helix polymer of nucleotides made of a sugar, a phosphate and one of four bases, complementary base pairing held by weak hydrogen bonds, genes as sections of DNA coding for proteins, the genome, and why people with the same genes can differ.

What you need to know

Answer each one before you reveal it.

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Key term

Describe the relationship between a gene, the genome and the proteins an organism makes.

Key term

What is the repeating unit from which the DNA polymer is built?

Key term

Describe the overall shape of a DNA molecule.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is the repeating unit from which the DNA polymer is built?

    Model answer

    DNA is built from repeating units called nucleotides.

  2. 2

    Describe the overall shape of a DNA molecule.

    Model answer

    Two strands are coiled around each other to form a double helix.

  3. 3

    Name the three parts that make up a single DNA nucleotide.

    Model answer

    A sugar, a phosphate group and one of four bases.

  4. 4

    To which part of a nucleotide is the base attached?

    Model answer

    The base is attached to the sugar.

  5. 5

    How many different bases are found in DNA?

    Model answer

    There are four different bases.

  6. 6

    What type of bond holds a pair of bases together across the two strands?

    Model answer

    Weak hydrogen bonds hold each base pair together.

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BWater plants die and decay.
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