Lecture 6: Nucleotides and Nucleic Acids Flashcards

1
Q

what is DNA?

A

hereditary material in almost all organisms

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2
Q

what is the function of DNA?

A

storage of genetic information for protein synthesis

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3
Q

RNA is involved in the expression of genetic material through transcription by ___RNA and translation by __RNA and __ RNA

A

M and R

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4
Q

a variety of small RNA molecules play a regulatory roles in ___ in the cell

A

gene expession

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5
Q

all cellular lifeforms on earth use __ to store genetic information, but some viruses use ___ instead

A

DNA; RNA

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6
Q

what are the building blocks of DNA and RNA?

A

nucleotides

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7
Q

all nucleotides are composed of what three components?

A
  1. nitrogenous base
  2. five-carbon sugar
  3. phosphate group
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8
Q

the ___ uniquely characterizes a nucleic acid and is a form of information

A

sequence of bases

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9
Q

nitrogenous bases are derivatives of either __ or __

A

pyrimidine or purine

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10
Q

the rings in both pyrimidines and purines are referred to as __, meaning they contain elements in addition to carbon

A

heterocycles

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11
Q

the ring structure of purines is the fusion of what two rings?

A

pyrimidine and imidazole rings

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12
Q

RNA and DNA have the same bases, except that RNA contains __- instead of thymine

A

uracil

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13
Q

purines have ___ heterocycles

A

2

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14
Q

pyrimidines have ___ heterocycles

A

1

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15
Q

which nucleotides are purines?

A

adenine and guanine

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16
Q

which nucleotides are pyrimidines?

A

thymine, uracil, cytosine

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17
Q

what toxic compound is found in chocolate, tea, and cola (why dogs cant have it)?

A

theobromine

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18
Q

adenosine is a component of ___ and therefore involved in energy and many biochemical functions

A

ATP

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19
Q

give 6 examples of biochemical (physiological) roles of adenosine in the body

A
  1. hormonal functions
  2. blood vessel dialation
  3. smooth muscle contraction
  4. neurotransmitter release
  5. metabolism of fat
  6. regulates sleep/wake
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20
Q

upon long periods of wakefulness, adenosine levels __ and promote sleepiness by interacting with __ receptors

A

rise; neuron

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21
Q

caffeine is a structural mimic of ___ and blocks the receptors and function (making you less sleepy)

A

adenosine

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22
Q

nitrogenous bases are relatively ___ (hydrophilic or hydrophobic)

A

hydrophobic

23
Q

because of their aromaticity, nitrogenous bases absorb UV radiation at ___nm very strongly

A

260

24
Q

the planar shape of nitrogenous bases allows them to participate in __ interactions with other aromatic groups, like side chains on certain amino acids

A

stacking

25
Q

what are nucleosides?

A

nitrogenous base covalently joined to a 5C sugar (ribose)

26
Q

nucleotides are nucleosides with ___ group on the 5’C of the sugar

A

phosphate

27
Q

multiple phosphate groups can be linked by ___

A

phosphoanhydride linkages

28
Q

ATP is an energy carrier and provides energy due to the energy carried in its ___

A

anhydride bonds

29
Q

a polynucleotide chain has individuality determined by the __

A

sequence of bases

30
Q

in nucleic acids, the ribose of each nucleotide is joined by a ___ bond

A

phosphodiester

31
Q

a phosphodiester bond is a ___ group covalently attached to the C5’ ___ of one sugar and the C3’ ___ of another sugar

A

hydroxyl x2

32
Q

molecules begin with the ___ phosphate and end with the __ hydroxyl group (5’/3’)

A

5’; 3’

33
Q

what is the directionality of nucleic acids?

A

5’-3’

34
Q

nitrogenous bases have groups that can participate in H bonding (t/f)

A

true

35
Q

hydrogen bonding is important for (2)

A
  1. double stranded DNA structure

2. interaction with DNA binding proteins

36
Q

pyrimidines and purines only pair with one another (1 pyrimidine and 1 purine) (t/f)

A

true

37
Q

the bottom strand directionality is ___ to the top strand

A

anti-parallel

38
Q

a gene is nothing more than a ___

A

DNA sequence

39
Q

the double helix structure of DNA forms spontaneously in water (t/f)

A

true

40
Q

the double helix of DNA is stabilized by three major interaction types

A
  1. hydrogen bonding
  2. hydrophobic affect
  3. stacking interactions
41
Q

hydrogen binding occurs between ___ of DNA

A

bases of complementary strands

42
Q

the hydrophobic effect causes nitrogenous bases of DNA helix to be ___

A

shielded from contact with water

43
Q

which structure of the DNA molecule is more hydrophilic?

A

sugar-phosphate backbone

44
Q

stacking interactions occur between __ of DNA

A

bases on the same strand

45
Q

stacked bases interact with each other through ___ between adjacent planar bases

A

van der waals forces

46
Q

describe how the hydrophobic effect affects the creation of the double helix shape of DNA

A

adopts a twisted structure to shield hydrophobic molecules from water

47
Q

each adjacent bases pair is separated by a distance that is ideal for the formation of

A

van der waals forces

48
Q

what causes the DNA helix to have major and minor grooves?

A

the 2 glycosidic bonds are not diametrically opposite each other

49
Q

in the DNA helix, each base pair has a larger and smaller side which define the ___

A

major and minor grooves

50
Q

proteins essential to transcription and translation typically bind to DNA at the __

A

major groove

51
Q

how does a protein bind to the DNA double helix?

A

functional groups on the amino acid side-chains interact with the functional groups of the nitrogenous bases in the major groove

52
Q

the major groove is lined with potential H-bond __

A

acceptors

53
Q

the minor groove is lined with potential H-bond __

A

donnors

54
Q

3 reasons why the major groove is the primary site of specific interaction by DNA binding proteins

A
  1. fits a protein structure
  2. more information exposed
  3. more diversity in pattern of molecular interaction sites