Lecture 6 Flashcards

1
Q

Which base does RNA tend to have?

A

Uracil as opposed to thymine

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2
Q

What is the most important difference between DNA and RNA?

A

DNA lacks the 2’ -OH group

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3
Q

What are the similarities between DNA and RNA?

A

•Both have a 5’ and 3’ end
•Both carry a strong negative charge

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4
Q

What is the charge of each part of the nucleotide?

A
  • Bases don’t carry a charge
  • Sugars don’t carry a charge
  • Phosphate groups have a negative charge
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5
Q

What is the backbone of nucleic acids?

A

The sugar phosphate structure

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6
Q

What is the polarity of the backbone of nucleic acids?

A

It is polar

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7
Q

What kind of bonds can the phosphates of nucleotides form?

A

Hydrogen bonds and ionic interactions

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8
Q

Which backbone is more polar? RNA or DNA?

A

RNA is more polar because of the hydroxyl group

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9
Q

How many potential hydrogen bonds can RNA form?

A

Three

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10
Q

What is the polarity of the bases themselves?

A

They are relatively non-polar but can form H-bonds

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11
Q

What is the solubility of bases in aqueous environments?

A

The bases are relatively low solubility

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12
Q

What order are the primary structure of Nucleic acids written?

A

5’ to 3’ Ex. 5’-ATGCAATG-3’

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13
Q

What is the Primary Structure?

A

The sequence of monomers within a polymeric structures. In nucleic acids its the sequence of nucleotides within the larger polymeric nucleic acid structure

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14
Q

What is a Mononucleotide?

A

A single nucleotide

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15
Q

What is a Dinucleotide?

A

Two nucleotides bonded by a phosphodiester bond

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15
Q

What is a Dinucleotide?

A

Two nucleotides bonded by a phosphodiester bond

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16
Q

What are examples of Mononucleotides?

A

ATP, ADP, FMN

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17
Q

What are examples of Dinucleotides?

A

FAD, NAD+, dCdG

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18
Q

What is a Oligonucleotide?

A

Relatively short nucleotide chain?

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19
Q

What is a Polynucleotide?

A

A large number of nucleotides in a polymer

20
Q

When are mono-/di-/tri- prefixes used?

A

When phosphates attached to a single carbon/OH group

21
Q

When are bis- or tris- (ex, Adenosine 2’,5’ bisphosphate) prefixes used?

A

When phosphates are attached to multiple carbon/OH groups

22
Q

What would be a situation where Phosphodiester bonds need to be broken?

A

If one were to ingest nucleic acids in order to free the nucleotides

23
Q

What would the products of Hydrolysis of a Phosphodiester bond?

A
  • A hydroxyl
  • Phosphate group that is no longer attached
  • And a free hydrogen
24
Q

What happens in RNA when the pH is > 10?

A

Spontaneous Hydrolysis of Phosphodiester bonds occur

25
Q

What does Spontaneous Hydrolysis of Phosphodiester bonds start with?

A

A hydroxyl acting as a base

26
Q

What is the first product of Spontaneous Hydrolysis of Phosphodiester bonds?

A

A 5’ OH attached to the 5’ C

27
Q

What is the second product of Spontaneous Hydrolysis of Phosphodiester bonds?

A

Either a 2’ or a 3’ phosphoester attached

28
Q

Why is the Spontaneous Hydrolysis of Phosphodiester bonds important?

A

Because it doesn’t happen in DNA

29
Q

Why is DNA more stable than RNA in alkaline conditions?

A

Because DNA doesn’t undergo Spontaneous Hydrolysis of Phosphodiester bonds because it doesn’t have the 2’ OH group

30
Q

What does the spontaneous deamination of cytosine form?

A

Uracil and an Ammonia

31
Q

What could occur if the spontaneous deamination of cytosine into uracil goes uncorrected?

A

It can cause DNA mutation

32
Q

What changes in cytosine when it converts to uracil?

A

The NH2 on cytosine is replaced with a carbonyl and the nitrogen at position 3 gains a hydrogen

33
Q

What happens if Uracil is found in DNA?

A

Specific DNA repair mechanisms will recognize the lack of methyl group on U and remove it

34
Q

What is dideoxynucleotide used for?

A

In lab scenarios where they don’t want a DNA chain to extend indefinitely so it has H at both 2’ and 3’ instead of one hydroxyl

35
Q

What does a Phosphodiester have to contain?

A

Two carbons attached to an phosphate

36
Q

What is a Phosphoanhydride?

A

To phosphates attached to an oxygen

37
Q

What are the properties of the bases in nucleic acid structures?

A
  • Heterocyclic
  • Aromatic, electron delocalization
  • Basically planar, slight pucker in purine base
  • Poorly soluble
  • Largely hydrophobic with some polar groups
38
Q

What is always seen with electron delocalization in aromatic structures?

A

UV absorbance

39
Q

How do nucleic acids tend to organize themselves since the bases are hydrophobic and the backbone is polar?

A

The sugar phosphate backbones are usually on the outside where they can interact with water

40
Q

What kind of light do Nucleic acids absorb?

A

UV light

41
Q

At what wavelengths does DNA absorb the most?

A

280nm and approx half that at 260nm

42
Q

Where do proteins tend to absorb more strongly?

A

At 280nm

43
Q

What does comparing the absorbance at 260 and 280nm do?

A

Tells us the purity of a DNA sample. 1.95 for pure DNA and will decrease if there is protein present

44
Q

What kind of relationship is seen with absorbance and concentration of DNA?

A

As DNA concentration goes up, so does absorption at a constant wavelength

45
Q

What does the Beer-Lambert Law do?

A

Relates concentration to absorbance

46
Q

What is the absorbance related to?

A

The concentration of DNA

47
Q

What is each chain in the double helix associated by?

A

Non covalent interactions with each other