U6 Flashcards

1
Q

proteins as structural components

A

skin, bones, tendons, muscles

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2
Q

catalytic agents

A

enzymes

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3
Q

regulating agents

A

hormones

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4
Q

immune agents

A

antigens and antibodeis

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5
Q

carriers

A

myoglobin and hemoglobin - O2 and CO2

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6
Q

nutritional role of proteins

A

provide AA and N

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7
Q

functions of protiens in food

A
water binding - texture 
emulsifiers 
gel forming
coagulating 
dough forming
palatability
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8
Q

what is palatablity

A

taste, texture, food quality

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9
Q

what protein in bread makes it palatable

A

gluten

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10
Q

what forms when milk coagulates. what products does this make

A

a curd. cheese, yogurt, sour cream

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11
Q

what forms when soy proteins coagulates. what product does this make

A

curd. tofu

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12
Q

what product is protein emulsification important for

A

sausages

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13
Q

endogenous enzymes

A

detrimental catalytic behavior in proteins - autolytic

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14
Q

exogenous enzymes

A

supplied by microbes in food

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15
Q

examples of beneficial catalytic behavior

A

proteases - tenderize meat
lipases - flavor development
amylases - form corn syrup.sugar products

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16
Q

example of a flavor potentiator

A

MSG - monosodium glutamate

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17
Q

examples of protein sources other than milk, eggs, and meat

A

rapeseed, beans, peas, leaves, microbes

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18
Q

what methods make meat analogs from soybean protein

A

texturization using extrusion

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19
Q

how many amino acids

A

20

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20
Q

what is the alpha carbon

A

connected to both NH2 and COOH groups

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21
Q

when is the AA protonated

A

low pH

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22
Q

when is the AA deprotonated

A

high pH

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23
Q

what is a zwitterion

A

COO- and NH3+. net charge zero

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24
Q

when does the zwitterion occur

A

isoelectric point

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25
Q

formula for isoelectric point

A

pI = (pk1 + pk2)/2

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26
Q

amino acids have attributes of a … (since the neutral form is still charged

A

salt

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27
Q

what properties do AA have that are similar to a salt

A
  1. crystalline strucutre
  2. wate soluble
  3. decompose at high temperatuers
  4. amphoteric - acid and bases
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28
Q

what occurs due to AA having 4 different substituents

A

optical isomerism and ability to rotate plant-polarized light. not superimposable

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29
Q

D or L?

A

both occur - racemic mixtures. but only L can form proteins

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30
Q

what is on the right for D and on the left for L

A

hyrgogen of alpha carbon

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31
Q

7 categories of amino acids

A
  1. aliphatic
  2. hydroxyl
  3. carboxyl
  4. base
  5. aromatic
  6. sulfur-containing
  7. imino
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32
Q

5 types of aliphatic AAs

A

glycine, alanine, valine, leucine, isoleucine

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33
Q

defining feature of aliphatic AA

A

hydrophobic

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34
Q

3 types of hydroxyl AA

A

serine, threonine, tryosine

35
Q

defining feature of hydroxyl AA

A

presence of OH group

36
Q

bonds that hydroxyl AAs make

A

h bonds
diester links
o-glycosidic links

37
Q

2 types of carboxyl AA

A

aspartic acid and glutamic acid

38
Q

defining feature of carboxyl AA

A

acidic. negative at pH7

isoelectric point is

39
Q

bond that carboxyl AA can make

A

N-glycosidic link

40
Q

what form do carboxyl AAs show in their natural form

A

amide - NH2. aspargie and glutamine

41
Q

3 types of basic AA

A

histidine, lysine, arginine

42
Q

defining feature of basic AA

A

basic - positive at pH7. isoelectric point is >ph7

43
Q

what R group does histdine have

A

imidazole

44
Q

what reaction does lysine do

A

maillard

45
Q

what R group does arginine have

A

guanidine

46
Q

3 types of aromatic AA

A

phenylalanine
tyrosine
tryptophan

47
Q

which amino acid is in 2 groups

A

tyrosine

48
Q

defining feature of aromatic AA

A

presence of aromatic group - absorbs UV light

49
Q

what bonds can aromatic AA form

A

hydrophobic interactions

50
Q

3 sulfur contianing AA

A

cysteine and methionine. cystine - which is the cysteine dimer

51
Q

defining feature of sulfur AA

A

presence of a sulfur compound

52
Q

what bonds can sulfur AA undego

A

disulfide crosslinks

53
Q

what is a disulfide crosslink

A

RSSR - dimer of cysteine molecules, cystine, between peptides or within a peptide

54
Q

2 types of imino aicds

A

proline and hydroxyproline

55
Q

are iminoacids amino acids?

A

no - NH instead of NH2

56
Q

what structure does proline interfere with and why

A

alpha helix because its incapable of forming hydrogen bonds

57
Q

what increases as aliphatic AA chain lengthens

A

hydrophobicity

58
Q

what is a diester link

A

one phosphate group linked to 2 hydroxyl AA via ester linkages

59
Q

which is more acidic - aspartic or glutamic acid

A

aspartic

60
Q

what does MSG stand for

A

monosodium glutamate

61
Q

what reaction do carboxylic AA undergo

A

non-enzymatic browning - serve as reduction points for reducing sugars

62
Q

what is more polar - amide or acid form of carboxyl AA

A

amide. makes it more watersoluble

63
Q

is the sulfhydryl group acidic or basic

A

basic

64
Q

what type of proteins contain iminoAA

A

structural

65
Q

true or false - pH has no effect on charges of the side chains

A

false.
high ph - convert NH3 to NH2. supress + charge
low pH - convert COO to COOH. supress -

66
Q

when is a protein least soluble

A

when it’s neutral at its isoelectric point

67
Q

how many essential AA

A

9

68
Q

what causes flavor from proteins

A

free AA and peptides

69
Q

what do protein hydrolases do in food

A

make meaty/broth flavor

70
Q

how do sulfur containing AA contribute to flavor

A

breaking down when heated releases H2S

71
Q

what is responsible for bitter flavors

A

peptides

72
Q

what is putrefaction

A

decay of proteins by enzymatic denaturation or decarboxylation by microbes. causes bad flavors and odors

73
Q

True or false: cysteine is a peptide because it is formed of 2 AA

A

false

74
Q

True or false: the isoelectric point of proteins is controlled by COOH and NH2 groups attached to the alpha carbon

A

false

75
Q

A longer aliphatic chain in an AA will increase its…

A

hydrophobicity

76
Q

Amino acids are optically active compounds because they have … alpha carbon atom

A

asymetric, chiral

77
Q

The amphoteric properties of proteins help regulate the … of the human body

A

ph

78
Q

The first carbon atom that attaches to a functional group is called…

A

alpha carbon

79
Q

Coagulating milk casein is the main mechanism to produce

A

cheese

80
Q

True or false: proline is considered an alpha amino acid

A

false

81
Q

When the AA has its alpha amine group to the left, it rotates light

A

counterclockwise

82
Q

AA can act as acids or bases, hence they are…

A

amphoteric

83
Q

Disulfide crosslinks result from the presence of … in amino acids

A

sulfhydryl (methionine doesn’t form them)

84
Q

The ability of AA to rotate plane-polarized light is…

A

optical isomerism