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Genetics Tuskegee > Biochem Final > Flashcards

Biochem Final Flashcards

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1
Q

The strongest non-covalent interactions are

A

ionic interactions

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2
Q

Which of the following components is bonded to the backbone chain of DNA by phosphodiester bond?

A

deoxyribose sugar molecules

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3
Q

If the following two reactions were coupled, what would be the ΔG° for the overall exergonic reaction?
Glucose + Pi —–> Glucose-6-Phosphate ΔG° = 21kj/mol
ATP + H20 ——> ADP + Pi ΔG° = -31kj/mol

A

-10 kj/mol

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4
Q

Fatty acid anions with two tails assemble into ________ in aqueous solution.

A

lipid bilayers

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5
Q

Which of the following biopolymers is correctly paired with the bond that forms between the monomers?

A

DNA; phosphodiester bond

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6
Q

Which of the following would be the strongest acid?

A

oxalic acid, pK = 1.25

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7
Q

The replication of DNA is made possible by the presence of ________ strands in the double helix of DNA.

A

complementary

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8
Q

The DNA strand that serves as the template for the synthesis of RNA is often called the

A

noncoding strand

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9
Q

What term is used to describe the exclusion of nonpolar substances from an aqueous solution?

A

hydrophobic effect

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10
Q

Photosynthetic organiss use energy from the sun to reduce ______ to _______.

A

CO2; carbohydrates

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11
Q

In aqueous solutions, globules of up to several thousand amphiphilic molecules arranged with the hydrophillic groups on the surface and the hydrophobic groups buried in the center are called

A

micelles

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12
Q

Which DNA base pair is held ogether by two hydrogen bonds

A

adenine and thymine

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13
Q

Which of the following statements concerning the double helix structure present in DNA molecules is correct?

A

Base pairings between strands always involve one pyrimidine base and one purine base

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14
Q

Polynucleotides are cleaved within the strands by

A

endonucleases

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15
Q

A phosphate buffer solution at a pH = 6.86 would have equal amounts of phosphate in the _________ form and the H2PO4- form.

A

HPO4^2-

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16
Q

Which of the major types of biomolecules are never found in polymeric form?

A

lipids

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17
Q

Which of the following non-covalent interactions is the most important in maintaining the structure of the double helix?

A

base stacking between adjacent bases

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18
Q

Which of the biopolymers is correctly paired with its major function?

A

polysaccharide; energy storage

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19
Q

The pH at the midpoint of an acid/base titration is

A

equal to the pK of the corresponding acid

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20
Q

If a solution is buffered at a pH of 4.70, then the addition of a small amount of acid will cause the solution to have a pH of approximately

A

4.70

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21
Q

Amphiphilic molecules

A

have both hydrophilic and hydrophobic groups

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22
Q

Name the major pyrimidine bases found in DNA

A

cytosine and thymine

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23
Q

The pK of [NH4+]/[NH3] buffer is 9.25. What is the optimum buffering range for this compound?

A

pH = 8.75 - 9.75

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24
Q

Which of the following molecules would be prevented from readily crossing a lipid bilayer?

A

sodium ions
glucose
potassium ions
water

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25
Q

In an aqueous solution, if the [OH-] is 3.0x10^-5 M, what is the [H+]?

A

3.3 x 10^-10

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26
Q

At any given moment, a single water molecules participates in _________ strong hydrogen bond(s). The role played by the water molecule is best characterized as __________.

A

two; one as a H-bond donor, one as a H-bond acceptor

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27
Q

A thermodynamically unfavorable chemical reaction can occur in a cell because

A

the unfavorable reaction can be coupled to a favorable reaction

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28
Q

RNA molecules differ from DNA molecules in that they

A

are single stranded rather than double stranded

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29
Q

A spontaneous process always has

A

ΔG < 0

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30
Q

Which of the following shows the buffer that is found in the blood stream?

A

H2CO3 ——-> HCO3- + H+

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31
Q

The melting point of DNA is always higher in DNA with

A

high GC content

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32
Q

A base found exclusively in DNA is __________ while ___________ is found only in RNA.

A

thymine; uracil

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33
Q

Which of the following is a physical property of water that results from hydrogen bonding?

A

ability to solubilize polar molecules
high surface tension
a solid state that is less dense than the liquid state
high boiling point relative to molecular weight

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34
Q

If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?

A

75

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35
Q

Any given nucleotide in a nucleic acid contains

A

one sugar, one base, and one phosphate

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36
Q

Which of the following describes the difference between ribose and deoxyribose?

A

Deoxyribose has one less oxygen atom than ribose

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37
Q

Entropy is used to measure

A

randomness

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38
Q

Which of the following is the best explaination for the hydrophobic effect?

A

It is an entropic effect, caused by the desire of water molecules to increase their entropy by excluding hydrophobic groups, which they must otherwise surround with highly ordered structures

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39
Q

Bacteria and archaea typically have fewer than ___________ genes while plants and animals typically have greater than ___________ genes.

A

5,000; 10,000

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40
Q

Which of the following shows the intracellular buffer?

A

H2PO4- ——-> HPO4^2- + H+

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41
Q

If the pK values for phosphoric acid are 2.15, 6.82, and 12.38, ___________ would predominate at pH 5 while __________ would predominate at pH 10.

A

H2PO4-; HPO4^2-

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42
Q

The blood buffering syste is based on:

A

the control of the bicarbonate content by the kidneys
the decrease of the blood pH due to the production of H+
the reaction of CO2 with H2O to form carbonic acid
the ionization of aqueous carbonic acid to H+ and the bicarbonate anion

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43
Q

What is the [H+] of an aqueous solution with a pH of 6.2?

A

6.3x10^-7

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44
Q

Protein folding in vivo is assisted by a

A

molecular chaperones

45
Q

Quaternary structure is possible for a protein only when

A

two or more protein chains are present

46
Q

Which of the following details the nucleotide-binding site when tubulin dimers assemble into microtubules?

A

the alpha site is bound to GTP; the beta site is bound to GDP

47
Q

Lysine, a positively charge amino acid, can form a salt bridge by associating with a nearby ___________ residue.

A

glutamic acid

48
Q

Which of the following correctly describes the sequence of events in the myosin-actin cycle?

A

ATP binds to myosin, myosin release from actin, myosin binds to another actin subunit, release of Pi and ADP, stretched myosin returns to original conformation

49
Q

Myoglobin is ____________; hemoglobin is ____________.

A

monomeric; tetrameric

50
Q

The central ion of the heme group of hemoglobin is

A

Fe^2+

51
Q

If the following mixture of proteins was applied to a size-exclusion chromatography column, what would be the order of elution? Proteins with molecular weights: myoglobin (17.7 kDa), hemoglobin (64.5 kDa), lysozyme (14.3 kDa) and triose phosphate isomerase (57.4 kDa)

A

hemoglobin, triose phosphate isomerase, myoglobin, lysozyme

52
Q

Proteins are made of ___________ which contains __________.

A

alpha-amino acids; a carboxylate group and a primary or secondary amine

53
Q

Which of these characteristics is not true for the alpha helix?

A

The side chains of the amino acid residues extend inward from the helix

54
Q

The heads of kinesin bind to ___________; the light chains of kinesin bind to __________.

A

collagen fibers; proteins in the cell membrane

55
Q

The primary structure of protein represents

A

linear sequence of amino acids joined by peptide bonds

56
Q

What level of protein structure is created by the binding of several peptides to produce a functional protein?

A

quaternary

57
Q

The secondary structure of myoglobin is mainly made of eight

A

alpha-helices

58
Q

When a cell moves along a surface, actin _________ occurs at the leading edge while __________ occurs at the trailing edge

A

polymerization; depolymerization

59
Q

A plot of the binding of oxygen to myoglobin as a function of pO2 gives a ___________ shape; a similar plot for hemoglobin gives a ___________ shape.

A

hyperbolic; sigmoidal

60
Q

At pH 3, how many charged groups are present in the pentapeptide Ala-Asp-His-Ser-Lys?

A

3

61
Q

Using the figure below, determine what type of column chromatography is being used to separate the mixture of proteins into individual proteins?

A

size-exclusion chromatography

62
Q

Which allosteric effector has the greatest ability to stabilize the deoxy state of hemoglobin?

A

2,3-Bisphosphoglycerate

63
Q

The formation of a peptide bond is best described as

A

a dehydration reaction

64
Q

For a globular protein that is found in the cytosol, _________ would most likely be found in the proteins interior while __________ would most likely be found on the surface (Use the Hydrophobicity Scale)

A

Leu; Ser

65
Q

Bone and tendons contain _________ while hair and nails contain _________.

A

collagen; keratin

66
Q

Which of the following explains the conversion of hemoglobin subunits from deoxy to oxy state?

A

all four subunits switch simultaneously

67
Q

A fully functional hemoglobin molecule has ___________ structure.

A

quaternary

68
Q

When oxygen is bound to the heme group of myoglobin, it is coordinated between ___________ and ____________.

A

E7 His; Fe^2+ of heme

69
Q

Which of the following statements about the structure of myoglobin is FALSE?

A

Myoglobin contains both types of secondary structure

70
Q

During the formation of microfilaments, which of the following occurs?

A

ATP hydrolysis is catalyzed by F-actin

71
Q

The disulfide bond between two cysteine molecules:

A

is a covalent bond formed by oxidation

72
Q

Which of these characteristics does not describe the beta sheet?

A

Parallel beta sheets are most common secondary structure

73
Q

In the peptide Try-Ser-Tyr, Tyr is at the

A

C-terminus

74
Q

What is the most prevalent secondary structure observed in the proteins of intermediate filament

A

beta-sheets

75
Q

What type of attractive force is responsible for maintaining the secondary structure of a protein?

A

hydrogen bonds between carbonyl and amine groups of peptide bonds

76
Q

In which of the following separation method where proteins are separated on the basis of their net charge?

A

ion exchange chromatography

77
Q

Which of the following fibers is correctly paried with the protein that forms the fiber?

A

intermediate filaments: keratin
microfilaments: actin
microtubule: tubulin

78
Q

Which of the following correctly describes the sequence of events on the kinesin reaction cycle? For simplicity, the two heads are referred to as head 1 and head 2. Head 1 starts as the leading head.

A

ATP binds to head 1, head 2 swings forward, head 2 binds to tubulin, ADP release from head 2, ATP hydrolysis in head 1, head 1 releases tubulin

79
Q

The idea that binding of one molecule of oxygen to hemoglobin enhances further binding of oxygen to hemoglobin is called

A

cooperativity

80
Q

What is the most common type of secondary structure in a protein

A

alpha helix

81
Q

An uncatalyzed reaction has a rate of 4.2x10^-7 sec^-1. When an enzyme is added the rate is 3.2x10^4 sec^-1. Calculate the rate enhancement caused by the enzyme. (rate of enhancement = catalyzed/uncatalyzed)

A

7.6x10^10

82
Q

What three amino acids are found in the catalytic triad of chymotrypsin?

A

Asp, His, Ser

83
Q

Km is a measure of

A

binding efficiency of substrate by enzyme

84
Q

What is the function of enzymes within living systems?

A

catalysts

85
Q

Some irreversible inhibitors are called ____________ because they bind to the active site of the enzyme and begin the catalytic process, just like a normal substrate

A

suicide substrates

86
Q

The oxidized form of NADH is

A

NAD+

87
Q

A zymogen is

A

an inactive precursor of an enzyme

88
Q

When an enzyme is saturated with substrate

A

the reaction velocity approaches a maximum

89
Q

Which of the following is mobilized for energy use by a phosphorolysis reaction, not a hydrolysis?

A

glycogen

90
Q

A lineweaver-burk plot is a

A

double reciprocal plot

91
Q

Which of the following is a correct skeletal equation for a hydrolysis reaction involving adenosine triphosphate?

A

ATP —–> ADP + Pi

92
Q

An enzyme active site is the location in an enzyme where substrate molecules

A

undergo change

93
Q

The mechanism of action for most antihistamines, which are used to alleviate allergy symtoms, is based on ________ inhibition

A

competitive

94
Q

Which of the following is used to move lipids around the bloodstream?

A

lipoproteins

95
Q

Which of the following is true about enzymes?

A

enzyme activities can often be regulated

96
Q

Degradation of proteins within a cell can occur within the ___________ or by use of ___________.

A

lysosome; a proteasome

97
Q

The coenzyme ____________ is a hydride ion (H+) receptor in a metabolic pathway.

A

NAD+

98
Q

Which of the following statements about metabolism is correct?

A

metabolsm is the sum total of all the biochemical reactions that take place in a living organism

99
Q

The highest point ina reaction coordinate diagram represents

A

the transition state

100
Q

Of the following ions, which would be most likely to participate in metal ion catalysis?

A

Zn^2+

101
Q

An extremely efficient enzyme has a ___________ Km and a ___________ Kcat.

A

small; large

102
Q

In a lineweaver-burk plot, the y-interceot indicates the value of

A

1/Vmax

103
Q

In the degradative pathway major nutrients are ___________ broken down, resulting in the synthesis of ___________.

A

exergonically; ATP

104
Q

The process by which nutrients are degraded in order to salvage their components and/or to generate energy is most specifically called:

A

catabolism

105
Q

The __________ stores glucose as glycogen and converts excess glucose to __________.

A

liver; fatty acids

106
Q

Generally speaking, ATP is produced by __________ reactions and used by ____________ reactions.

A

catabolic; anabolic

107
Q

The number of substrate molecules acted upon per minute by one molecule of enzyme is alled the

A

turnover number

108
Q

The correct notation for the reduced form of nicotinamide adenine dinucleotide is

A

NADH

109
Q

Plants are considered

A

photoautotrophs

Genetics Tuskegee (8 decks)

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