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28 Cards in this Set

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  • Back
Summarize the contribution to the understanding of DNA by: Linus Pauling
discovered that the molecules of some proteins have helical shapes
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.
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)
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.
List the three components of a nucleotide.
Nitrogenous base
List the nitrogen bases found in DNA.
A - adenine
G - guanine
C - cytosine
T - Thymine
Explain the significance of the base-pairing pattern.
Because they have different shapes, and different sites where hydrogne bonds can form adenine always bonds with thymine and guanine always bonds with cytosine.
Describe the structure of DNA.
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).
What kind of chemical bond holds the nitrogenous bases together in the middle of the molecule.
Adenine and thymine are connected by two hydrogen bonds (non-covalent) while guanine and cytosine are connected by three.
Explain why the two strands of DNA are said to be "antiparallel."
They run in opposite directions.
Explain the process of DNA replication.
produces two molecules, each of which is half-new and half-old DNA joined lengthwise to each other.
Explain why DNA replication is said to be "semiconservative."
each separated strand serves as a template to make an exact copy.
Describe the action of DNA polymerase in DNA proofreading and repair.
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.
Describe the action of DNA ligase in DNA proofreading and repair.
can link together DNA strands that have double-strand breaks (a break in both complementary strands of DNA).
A strand of DNA serves as a template for the formation of ______ instead of a copy of DNA.
mRNA (messenger RNA)
RNA uses ________ sugar
RNA bases are
A - Adenine
G - Guanine
C - Cytosine
U - Uracil
mRNA is a _______ strand, whereas DNA is a _______ strand
single - mRNA
double - DNA
Transcription begins when:
RNA polymerase binds to a "start" and then moves along to the end of a gene "stop".
The mRNA strand is "modified" and "edited" before leaving the nucleus by:
- 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).
In making mRNA from the DNA template,
RNA polymerase is used instead of DNA polymerase.
Every three bases in the code, in order, specify an _____ _____.
Amino acid
Each of these base triplets is called a ______.
The genetic code consists of ___ triplets that specify the 20 amino acids plus start and stop codons.
The _______ _____ is universal for all life forms.
Genetic Code