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BIOCHEM > First 50 > Flashcards

First 50 Flashcards

1
Q

The study of biochemistry attempts to explain

chemical processes at the atomic level.

biological processes at the molecular and cellular level.

the nature of life.

physical processes at the macromolecular level.

A

biological processes at the molecular and cellular level.

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2
Q

The __________ differentiates amino acids from one another.

number of silane groups

number of phosphoryl groups

side chains attached to the central carbon

number of hydroxyl groups

A

side chains attached to the central carbon

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3
Q

If the concentration of aspartate in the cell decreased, what would be the predicted outcome?

increased concentration of argininosuccinate

decreased concentration of citrulline

decreased concentration of fumarate

increased concentration of arginine

A

decreased concentration of fumarate

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4
Q

Plasmids are small, circular DNA molecules that are used in which of the following?

gene cloning

production of chromatin

cell movement

replication of nucleus

A

gene cloning

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5
Q

A hydrogen bond can best be described as a

strong covalent interaction.

strong ionic interaction.

weak noncovalent interaction.

weak covalent interaction.

A

weak noncovalent interaction.

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6
Q

Given a DNA sequence of 3’-CAT-5’, what is the complementary sequence in mRNA?

5’-GUA-3’

5’-AUG-3’

3’-GUA-5’

5’-GTA-3’

A

5’-GUA-3’

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7
Q

Bioinformatics shows that 98% of human DNA is identical to that of chimpanzees. If human DNA contains 3.2 billion nucleotides, how many nucleotides are different between the two species?

3.1 billion

64 million

3.1 million

640 million

A

64 million

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8
Q

Highly conserved gene sequences that encode proteins with the same function in different organisms are called __________ genes.

orthologous

conserved

parallel

antiparallel

A

orthologous

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9
Q

In DNA the phosphate groups are on the outside of the helix. Why does this stabilize the structure?

ionic interactions with the solvent

hydrogen bonding with itself

covalent binding to the solvent

It does not stabilize the structure.

A

ionic interactions with the solvent

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10
Q

What is the cause of the overall negative charge of a molecule of DNA?

hydrogen bonding between base pairs

the phosphate backbone

the sugars

the antiparallel orientation of the DNA

A

the phosphate backbone

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11
Q

The DNA double helix is stabilized by the interactions between nucleotides because of __________ between nucleotides.

hydrogen bonding

pi–pi stacking

sigma bonds

ionic interactions

A

pi–pi stacking

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12
Q

What side products of pyruvate are being converted into alcohol and carbon dioxide by yeast?

CO and NADH

CO2 and NADH

CO2 and NAD+

CO and NAD+

A

CO2 and NAD+

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13
Q

A requirement for a covalent bond to form between two atoms is that

there are unpaired electrons on each atom.

the atoms are ions.

both the atoms must be metals.

one of the atoms must be a halogen.

A

there are unpaired electrons on each atom.

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14
Q

The correct name for the VSEPR arrangement around a carbon in methane is

linear.

trigonal bipyrimidal.

tetrahedral.

octahedral.

A

tetrahedral.

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15
Q

Cell signaling and cell membranes are examples of functions performed by which biomolecule?

amino acid

nucleotide

simple sugar

fatty acid

A

fatty acid

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16
Q

The figure below shows an example of which functional group?

O=P=O

amino

hydroxyl

phosphoryl

methyl

A

phosphoryl

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17
Q

Triacylglycerols are neutral molecules made of

three fatty acid esters covalently linked to glycine.

three fatty acid esters covalently linked to glycerol.

two fatty acid esters covalently linked to glycine.

three acyls covalently linked to glycerol.

A

three fatty acid esters covalently linked to glycerol.

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18
Q

Vitamin B2 is a metabolite. Lack of vitamin B2 can lead to blurred vision and a swollen tongue. Vitamin B2 has such a strong effect on health because metabolites

are the catalysts that drive biochemical reactions necessary for life-sustaining processes.

are complex chemical reactions in cells.

process essential genetic information needed for life.

are needed for construction of microtubules.

A

are the catalysts that drive biochemical reactions necessary for life-sustaining processes.

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19
Q

Which of the following is the correct solar energy reaction that takes place on the sun?

4 He –> ^4He

^4He –> big 4 He

4 H –> ^ 4He

^4H –>4 H

A

4 H –> ^ 4He

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20
Q

What is the final molecule made from the oxidation of H2O by solar energy?

ozone

glucose

fructose

carbon dioxide

A

glucose

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21
Q

The difference between an oxidation reaction and a reduction reaction is that oxidation is the __________ and reduction is the __________.

loss of electrons; gain of electrons

gain of electrons; loss of electrons

loss of protons; gain of protons

gain of protons; loss of protons

A

loss of electrons; gain of electrons

22
Q

Which of the following is an example of a system?

the universe

the air

a test tube with reaction components

outer space

A

a test tube with reaction components

23
Q

A hot pack on your arm is an example of what kind of system?

open

closed

isolated

surroundings

A

closed

24
Q

The combustion of gasoline is considered exothermic because heat is

transferred from the surroundings to the system.

transferred from the system to the surroundings.

transferred to the universe.

not transferred.

A

transferred from the system to the surroundings.

25
Q

The change in entropy of a system is a function of a change in

temperature and pressure.

volume and pressure.

enthalpy and pressure.

enthalpy and temperature.

A

enthalpy and temperature.

26
Q

If a reaction has a delta H > 0 and a delta S < 0, then __________ and the reaction is __________ at all temperatures.

delta G < 0; spontaneous

delta G > 0; spontaneous

delta G < 0; nonspontaneous

delta G > 0; nonspontaneous

A

delta G > 0; nonspontaneous

27
Q

If the equilibrium constant (Keq) is greater than 1, which direction will the reaction proceed?

spontaneously to products

spontaneously to reactants

neither direction

Not enough information is given to determine the direction of reaction.

A

spontaneously to products

28
Q

Under what conditions could a biological reaction spontaneously proceed to reactants if the mc028-1.jpg?

Reactant concentrations are greater than product concentrations.

Product concentrations are greater than reactant concentrations.

Reactant concentrations are equal to product concentrations.

There are no conditions where this could happen.

A

Product concentrations are greater than reactant concentrations.

29
Q

The transfer of a phosphate from ATP to another molecule produces a(n)

low-energy intermediate.

highly reactive intermediate.

neutral energy intermediate.

It is not possible to transfer a phosphate to another molecule.

A

highly reactive intermediate.

30
Q

Under steady-state conditions in a mammalian cell, the adenine nucleotide concentrations are [ATP] = 3.3 mM, [ADP] = 1.2 mM, and [AMP] = 0.2 mM. What is the energy charge of this cell?

  1. 83
  2. 95
  3. 72
  4. 2
A

0.83

31
Q

Organisms on Earth cannot easily exist at temperatures below 0 C because at that temperature

hydrogen bonds cannot exist.

water does not exist in a tetrahedron.

ice crystals form in the organism.

proton hopping cannot occur.

A

ice crystals form in the organism.

32
Q

A hydrogen bond can form between a hydrogen atom on a(n)

electronegative donor group and another electronegative atom.

cationic atom and another hydrogen.

nonpolar donor group and an electronegative atom.

ionic atom and another anion.

A

electronegative donor group and another electronegative atom.

33
Q

The interaction between an amino group and a carboxylate group is best characterized as

hydrogen bonds.

ionic interactions.

van der Waals interactions.

a covalent bond.

A

ionic interactions.

34
Q

The interaction between nonpolar molecules is best characterized as

a hydrogen bond.

ionic interactions.

van der Waals interactions.

a covalent bond.

A

van der Waals interactions.

35
Q

How do plants, fungi, and bacteria avoid the damaging effects of a hypotonic environment?

flexible cells walls

rigid cells walls

semipermeable cell walls

photosynthesis

A

rigid cells walls

36
Q

Calculate the pH of a solution that contains 3.9 x 10x^-4M H+.

  1. 59
  2. 59
  3. 41
  4. 41
A

3.41

37
Q

Weak acids have a high pKa because the

HA concentration is high.

H+ concentration is high.

A− concentration is high.

HA concentration is low.

A

HA concentration is high.

38
Q

Given a solution with pH > pKa, what are the relative concentrations of A– and HA?

[HA] > [A–]

[HA] < [A–]

[HA] = [A–]

[HA] = [A–] = 1

A

[HA] < [A–]

39
Q

A molecule with hydrophobic and hydrophilic properties is best described as

a zwitterion.

amphipathic.

polar.

nonpolar.

A

amphipathic.

40
Q

The figure below shows part of the primary structure of DNA. Identify the nucleoside.

A

B

C

D

A

C

41
Q

Which form(s) of DNA exhibit(s) a right-handed helical structure?

A-DNA

B-DNA

Z-DNA

A-DNA and B-DNA

A

A-DNA and B-DNA

42
Q

Chargaff’s rule is that the amount of

A = G and the amount of C = T.

A = C = G = T.

A = T and the amount of C = G.

A = C and the amount of G = T.

A

A = T and the amount of C = G.

43
Q

The DNA double helix is considered to be a __________ structure.

primary

secondary

tertiary

quaternary

A

secondary

44
Q

Predict the complementary strand of the following DNA sequence: 5’-ATCTGAATCT-3’

5’-TCTAAGTCTA-3’

5’-TAGACTTAGA-3’

5’-ATCTGAATCT-3’

5’-AGATTCAGAT-3’

A

5’-AGATTCAGAT-3’

45
Q

The K+ ion concentration in a DNA sample is increased from 50 mM to 100 mM. The Tm will

remain the same.

decrease.

increase.

vary unpredictably.

A

increase.

46
Q

DNA strands containing 20 base pairs, 40 base pairs, and 60 base pairs were denatured and the results were graphed below. Identify the curve from the 60 base pair DNA strand.

A

B

C

Not enough information is included to determine the curve.

A

C

47
Q

A double helix that crosses itself in a right-handed twist is referred to as a

positive supercoil.

negative supercoil.

topoisomer.

linking number.

A

negative supercoil.

48
Q

Calculate the linking number for a B-DNA strand that contains 735 total base pairs.

50

61

67

70

A

70

49
Q

Predict how type I topoisomerases change the supercoil region.

Lk = 2

Lk = 1

Lk = –1

Lk = –2

A

Lk = –1

50
Q

Predict how type II topoisomerases change the supercoil region.

Lk = 2

Lk = 1

Lk = –1

Lk = –2

A

Lk = –2

BIOCHEM (7 decks)

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