Chapter 3 - Nucleic Acids Flashcards

0
Q

What does nucleosides lack?

A

Phosphates

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1
Q

Monomeric units with phosphates

A

Nucleotides

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2
Q

What are the two purine bases?

A

Adenine & Guanine (in both DNA and RNA)

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3
Q

What are the three pyrimidine bases?

A

Cytosine (in both DNA and RNA),
Thymine (in DNA)
Uracil (in RNA)

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4
Q

Where is the glycosidic bond of purines and pyrimidines?

A

Purines attached at N9 to sugar at C1’

Pyrimidines attached at N1 to sugar at C1’

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5
Q

What substrates do DNA and RNA synthesis require?

A

dNTP & NTP substrates

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6
Q

Nucleotides are linked through what kind of bond?

A

Phosphodiester bonds (between the 3’ and 5’ hydroxyl groups) to form long polymers

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7
Q

Reactive nucleoside triphosphates (dNTP’s or NTP’s) are added to growing polynucleotide chain at what end?

A

3’ end

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8
Q

List the Chargaff’s rules

A
  1. All tissues in the same species have the same % of all 4 nucleotides
  2. % of purines = % of pyrimidines
  3. %A = %T and %G = %C
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9
Q

What’s the bond between A & T?

A

2 H bonds

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10
Q

What’s the bond between C & G?

A

3 H bonds, which is stronger than the bond between A & T

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11
Q

What is double helix stabilized by?

A
  1. Hydrophobic interactions: base stacking
  2. H-bonding between bases purinepyrimidine
  3. Cations: neutralize the (-) charge on phosphates along the helix of DNA
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12
Q

Which kind of DNA forms under dehydrated, non-physiological conditions; right-handed helix

A

A form DNA (A-DNA)

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13
Q

Which kind of DNA forms when fully hydrated and under conditions in vivo; right-handed helix; majority of proteins recognize major groove

A

B-DNA

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14
Q

Found in G-C rich DNA sequences; left-handed helix; may be important in protein recognition & gene regulation

A

Z-DNA

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15
Q

Stability or melting temperature (Tm) is a function of what?

A

GC content

16
Q

What are the most common structures of RNA?

A

A-form double helices and hairpins

17
Q

What reads gene information encoded in mRNA copied from DNA?

A

tRNA

18
Q

What does tRNA do?

A

Transfers the appropriate amino acid to a growing polypeptide chain during protein synthesis