Lecture 6: Nucleotides and Nucleic Acids

Question 1

what is DNA?

Answer 1

hereditary material in almost all organisms

Question 2

what is the function of DNA?

Answer 2

storage of genetic information for protein synthesis

Question 3

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

Answer 3

M and R

Question 4

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

Answer 4

gene expession

Question 5

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

Answer 5

DNA; RNA

Question 6

what are the building blocks of DNA and RNA?

Answer 6

nucleotides

Question 7

all nucleotides are composed of what three components?

Answer 7

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

Question 8

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

Answer 8

sequence of bases

Question 9

nitrogenous bases are derivatives of either __ or __

Answer 9

pyrimidine or purine

Question 10

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

Answer 10

heterocycles

Question 11

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

Answer 11

pyrimidine and imidazole rings

Question 12

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

Answer 12

uracil

Question 13

purines have ___ heterocycles

Answer 13

2

Question 14

pyrimidines have ___ heterocycles

Answer 14

1

Question 15

which nucleotides are purines?

Answer 15

adenine and guanine

Question 16

which nucleotides are pyrimidines?

Answer 16

thymine, uracil, cytosine

Question 17

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

Answer 17

theobromine

Question 18

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

Answer 18

ATP

Question 19

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

Answer 19

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

Question 20

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

Answer 20

rise; neuron

Question 21

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

Answer 21

adenosine

Question 22

nitrogenous bases are relatively ___ (hydrophilic or hydrophobic)

Answer 22

hydrophobic

Question 23

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

Answer 23

260

Question 24

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

Answer 24

stacking

Question 25

what are nucleosides?

Answer 25

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

Question 26

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

Answer 26

phosphate

Question 27

multiple phosphate groups can be linked by ___

Answer 27

phosphoanhydride linkages

Question 28

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

Answer 28

anhydride bonds

Question 29

a polynucleotide chain has individuality determined by the __

Answer 29

sequence of bases

Question 30

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

Answer 30

phosphodiester

Question 31

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

Answer 31

hydroxyl x2

Question 32

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

Answer 32

5'; 3'

Question 33

what is the directionality of nucleic acids?

Answer 33

5'-3'

Question 34

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

Answer 34

true

Question 35

hydrogen bonding is important for (2)

Answer 35

1. double stranded DNA structure | 2. interaction with DNA binding proteins

Question 36

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

Answer 36

true

Question 37

the bottom strand directionality is ___ to the top strand

Answer 37

anti-parallel

Question 38

a gene is nothing more than a ___

Answer 38

DNA sequence

Question 39

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

Answer 39

true

Question 40

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

Answer 40

1. hydrogen bonding 2. hydrophobic affect 3. stacking interactions

Question 41

hydrogen binding occurs between ___ of DNA

Answer 41

bases of complementary strands

Question 42

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

Answer 42

shielded from contact with water

Question 43

which structure of the DNA molecule is more hydrophilic?

Answer 43

sugar-phosphate backbone

Question 44

stacking interactions occur between __ of DNA

Answer 44

bases on the same strand

Question 45

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

Answer 45

van der waals forces

Question 46

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

Answer 46

adopts a twisted structure to shield hydrophobic molecules from water

Question 47

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

Answer 47

van der waals forces

Question 48

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

Answer 48

the 2 glycosidic bonds are not diametrically opposite each other

Question 49

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

Answer 49

major and minor grooves

Question 50

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

Answer 50

major groove

Question 51

how does a protein bind to the DNA double helix?

Answer 51

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

Question 52

the major groove is lined with potential H-bond __

Answer 52

acceptors

Question 53

the minor groove is lined with potential H-bond __

Answer 53

donnors

Question 54

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

Answer 54

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