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MCAT > MCAT Biochemistry > Flashcards

MCAT Biochemistry Flashcards

Master of Biochem

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MCAT flashcards
1
Q

What two function groups do amino acids contain?

A

Amine and carboxyl group

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2
Q

What groups are attached to the alpha carbon

A

amine group, carboxyl group, a hydrogen atom, and an R group (specific to each amino acid)

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3
Q

proteinogenic amino acids are…?

A

The 20 main amino acids that have amino and carboxyl group attached to the alpha carbon (create proteins)

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4
Q

Which amino acid is achiral?

A

glycine

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5
Q

Which amino acid has an R configuration?

A

cysteine

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6
Q

Which amino acids have non-polar, non aromatic side chains?

A

glycine, alanine, valine, leucine, isoleucine, methionine, and proline.

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7
Q

Which amino acids have aromatic side chains?

A

tryptophan, phenylalanine, and tyrosine

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8
Q

Which amino acids have polar side chains?

A

serine, threonine, asparagine, glutamine, and cysteine

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9
Q

Which two amino acids have acidic (negatively charged) side chains

A

asparagine (aspartate specifically) and glutamine (glutamate)

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10
Q

Which amino acids have positive side chains?

A

lysine, arginine, and histidine

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11
Q

T/F Hydrophobic amino acids tend to be found on the interior of proteins

A

True

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12
Q

Amphoteric species are

A

molecules that can either accept or donate a proton, depending on the pH of their environment

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13
Q

T/F Ionizable groups tend to lose protons under acidic conditions and gain them in basic conditions

A

False they gain a proton in acidic conditions and lose a proton in basic conditions

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14
Q

If pH is less than the pKa, a majority of the species will be?

A

pronated

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15
Q

If pH is more than the pKa, a majority of the species will be ?

A

deprotonated

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16
Q

Each ionizable proton has its own pKa, at which is it half—____

A

half-deprotonated

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17
Q

Amino acids tend to be ___ charged under very acidic conditions

A

positively

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18
Q

zwitterions are

A

dipolar (one positive one negative) ions within an amino acid

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19
Q

At highly alkaline (basic) pH values, amino acids tend to be ____ charged

A

negatively

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20
Q

When the pH of a solution is approximately equal to the pKa of the solute, the solution acts as a ___-

A

buffer

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21
Q

isoelectric point is the

A

point in the pH where the molecule is electrically neutral

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22
Q

Amino acids with acidic side chains have a pI well ____ 6 and amino acids with a basic side chain have a pI well ____ 6

A

below, above

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23
Q

Peptides are composed of

A

amino acid subunits (also known as residues)

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24
Q

Dipeptides consist of

A

two amino acid residues

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25
Q

Tripeptides consist of

A

three amino acid residues

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26
Q

oligopeptides consist of

A

up to about 20 residues

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27
Q

polypeptides consist of

A

more than 20 residues

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28
Q

resides in peptides are joined together through…

A

peptide bonds

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29
Q

Peptide bond formation is accomplished through

A

Condensation or dehydration (addition of removal of water)

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30
Q

The free amino end is know as the amino terminus, or the ______

A

N-terminus (left side)

31
Q

The free carboxyl end is the carboxy terminus or the ______

A

C-terminus (right side)

32
Q

What are proteins?

A

they are polypeptides that range from a few amino acids in length up to thousands

33
Q

What are the four levels of protein structures

A

primary, secondary, tertiary, and quaternary

34
Q

What are the two most common secondary structures?

A

alpha helixes and beta pleated sheets

35
Q

What protein is the alpha helix an important structural component in?

A

keratin

36
Q

Which amino acid is rarely found in alpha helixes?

A

proline

37
Q

The tertiary structure of a protein is primary the result of ________ into the interior of the protein

A

hydrophobic amino acid side chains

38
Q

What bond is an important component in tertiary structures

A

disulfide bonds

39
Q

When do disulfide bonds form?

A

when two cysteine molecules become oxidized to form cystine, which creates loops

40
Q

What bonds form from secondary structures to tertiary structures

A

secondary structure forms, hydrophobic interactions, and then hydrogen bonds to collapse the protein

41
Q

What is the intermediate state between secondary and tertiary structures?

A

molten globules

42
Q

denaturation is when

A

a protein (usually tertiary structure), loses its shape/structure and loses its function

43
Q

What forms a solvation layer?

A

solvent molecules that come in contact with the solute, (forms around the solute)

44
Q

Are negative changes in entropy favorable or unfavorable?

A

unfavorable, because it makes the process non-spontaneous

45
Q

When do quaternary structures exist

A

when there is more than one polypeptide chain

46
Q

What proteins have a quaternary structure?

A

hemoglobin and immunoglobulins

47
Q

Where do conjugated proteins derive their function from?

A

From the covalent attachment of prosthetic groups

48
Q

Lipoproteins, glycoproteins, and nucleoproteins all have a….?

A

prosthetic group

49
Q

To reverse protein folding, a protein would need to undergo

A

denaturation

50
Q

What are the two main causes of denaturation?

A

heat and solutes

51
Q

why does heat denature a protein?

A

it overrides the hydrophobic interactions that hold a protein together

52
Q

Why do solutes denature proteins

A

they break apart disulfide bridges as well as hydrogen bonds that hold the alpha helix and beta sheets together

53
Q

Enzymes are ______

A

biological catalysts

54
Q

T/F enzymes lower activation energy

A

true

55
Q

Do enzymes increase or decrease the rate of reaction

A

increase

56
Q

Do enzymes alter the equilibrium constant?

A

no

57
Q

Are enzymes changed at all during the reaction?

A

no

58
Q

Are enzymes pH and temp sensitive?

A

yes

59
Q

Do enzymes effect the free energy (deltaG) of the reaction?

A

no

60
Q

Are enzymes specific?

A

yes

61
Q

Oxidoreductase function is to

A

catalyze oxidation-reduction reactions

62
Q

Transferase function is to

A

catalyze the movement of a functional group from one molecule to another

63
Q

Kinases transfer _______

A

phosphate groups

64
Q

Hydrolases function is to

A

catalyze the breakdown of a compound into two molecules by adding water

65
Q

Lyases function is to

A

catalyze the cleavage of a single molecule into two products

66
Q

Isomerases function is to

A

catalyze the rearrangement of bonds within a molecule

67
Q

Ligases function is to

A

catalyse addition or synthesis reactions, usually between larger and more similar molecules (require ATP)

68
Q

Endergonic reactions require

A

energy input

69
Q

Exergonic reactions give off

A

energy

70
Q

Catalysts such as enzymes help to lower the

A

activation energy of a reaction

71
Q

Lock and Key Theory suggests that

A

the enzyme active site is already in the appropriate confirmation for the right substrate to bind

72
Q

Induced fit model

A

During transitional state, both the substrate and enzyme undergo a conformational change to complement each other (requires energy)

73
Q
A

MCAT (2 decks)

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