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28 Cards in this Set
- Front
- Back
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Summarize the contribution to the understanding of DNA by: Linus Pauling
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discovered that the molecules of some proteins have helical shapes
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Summarize the contribution to the understanding of DNA by:
Watson and Crick |
discovered how the bases were paired on the inside of the helix, and thus the secret of heredity itself. They built a correct and complete description of DNA's structure.
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Summarize the contribution to the understanding of DNA by:
Maurice Wilkins |
it was Wilkins's idea to study DNA by X-ray crystallographic techniques, Wilkins applied X-ray techniques to the structural determination of nerve cell membranes and of ribonucleic acid (RNA)
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Summarize the contribution to the understanding of DNA by:
Rosalind Franklin. |
excellent X-ray photographs, Franklin had discovered that DNA could crystallize into two different forms, an A form and a B form. She also developed a method to separate the two forms.
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List the three components of a nucleotide.
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Sugar
Phosphate Nitrogenous base |
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List the nitrogen bases found in DNA.
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A - adenine
G - guanine C - cytosine T - Thymine |
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Explain the significance of the base-pairing pattern.
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Because they have different shapes, and different sites where hydrogne bonds can form adenine always bonds with thymine and guanine always bonds with cytosine.
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Describe the structure of DNA.
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The structure of DNA is illustrated by a right handed double helix, with about 10 nucleotide pairs per helical turn. Each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (non- covalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C).
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What kind of chemical bond holds the nitrogenous bases together in the middle of the molecule.
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Adenine and thymine are connected by two hydrogen bonds (non-covalent) while guanine and cytosine are connected by three.
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Explain why the two strands of DNA are said to be "antiparallel."
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They run in opposite directions.
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Explain the process of DNA replication.
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produces two molecules, each of which is half-new and half-old DNA joined lengthwise to each other.
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Explain why DNA replication is said to be "semiconservative."
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each separated strand serves as a template to make an exact copy.
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Describe the action of DNA polymerase in DNA proofreading and repair.
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is an enzyme,
adds new nucleotides to a strand, proofreads DNA strands to see that they are correct, derives energy from ATP for synthesis of DNA strands. |
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Describe the action of DNA ligase in DNA proofreading and repair.
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can link together DNA strands that have double-strand breaks (a break in both complementary strands of DNA).
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A strand of DNA serves as a template for the formation of ______ instead of a copy of DNA.
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mRNA (messenger RNA)
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RNA uses ________ sugar
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ribose
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RNA bases are
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A - Adenine
G - Guanine C - Cytosine U - Uracil |
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mRNA is a _______ strand, whereas DNA is a _______ strand
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single - mRNA
double - DNA |
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Transcription begins when:
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RNA polymerase binds to a "start" and then moves along to the end of a gene "stop".
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The mRNA strand is "modified" and "edited" before leaving the nucleus by:
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- Capping the 5' end with "start" signal.
- Ending the sequence with a "poly-A tail" at the 3' end. - Cutting out the noncoding portions of the transcription (introns). - Splicing together coding regions (exons). |
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In making mRNA from the DNA template,
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RNA polymerase is used instead of DNA polymerase.
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Every three bases in the code, in order, specify an _____ _____.
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Amino acid
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Each of these base triplets is called a ______.
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Codon
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The genetic code consists of ___ triplets that specify the 20 amino acids plus start and stop codons.
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61
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The _______ _____ is universal for all life forms.
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Genetic Code
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CCA =
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proline
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AGG =
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arginine
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GAG =
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glutamate
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