Chapter 16 (Homework) – Flashcards
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Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
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12
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What kind of chemical bond is found between paired bases of the DNA double helix?
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hydrogen
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What is meant by the description "antiparallel" regarding the strands that make up DNA?
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The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
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What determines the nucleotide sequence of the newly synthesized strand during DNA replication?
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the nucleotide sequence of the template strand
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As DNA replication continues and the replication bubble expands, the parental double helix is unwound and separated into its two component strands. This unwinding and separating of the DNA requires three different types of proteins: helicase, topoisomerase, and single-strand binding proteins.
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helicase - breaks H-bonds between bases; binds at the replication fork topoisomerase - breaks covalent bonds in DNA backbone; binds ahead of the replication fork single-strand binding - prevents H-bonds between bases; binds after the replication fork
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Complete the following vocabulary exercise related to DNA replication.
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1. During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a replication fork. 2. Okazaki fragments are the short sections of DNA that are synthesized on the lagging strand of the replication DNA. 3. The enzyme that can replicate DNA is called DNA polymerase. 4. The new DNA strand that grows continuously in the 5' to 3' direction is called the leading strand. 5. After replication is complete, the new DNAs, called daughter DNA, are identical to each other.
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At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
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5' A C G U U A G G 3'
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Which of the following best describes the addition of nucleotides to a growing DNA chain?
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A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate.
