U6

Question 1

proteins as structural components

Answer 1

skin, bones, tendons, muscles

Question 2

catalytic agents

Answer 2

enzymes

Question 3

regulating agents

Answer 3

hormones

Question 4

immune agents

Answer 4

antigens and antibodeis

Question 5

carriers

Answer 5

myoglobin and hemoglobin - O2 and CO2

Question 6

nutritional role of proteins

Answer 6

provide AA and N

Question 7

functions of protiens in food

Answer 7

water binding - texture 
emulsifiers 
gel forming
coagulating 
dough forming
palatability

Question 8

what is palatablity

Answer 8

taste, texture, food quality

Question 9

what protein in bread makes it palatable

Answer 9

gluten

Question 10

what forms when milk coagulates. what products does this make

Answer 10

a curd. cheese, yogurt, sour cream

Question 11

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

Answer 11

curd. tofu

Question 12

what product is protein emulsification important for

Answer 12

sausages

Question 13

endogenous enzymes

Answer 13

detrimental catalytic behavior in proteins - autolytic

Question 14

exogenous enzymes

Answer 14

supplied by microbes in food

Question 15

examples of beneficial catalytic behavior

Answer 15

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

Question 16

example of a flavor potentiator

Answer 16

MSG - monosodium glutamate

Question 17

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

Answer 17

rapeseed, beans, peas, leaves, microbes

Question 18

what methods make meat analogs from soybean protein

Answer 18

texturization using extrusion

Question 19

how many amino acids

Answer 19

20

Question 20

what is the alpha carbon

Answer 20

connected to both NH2 and COOH groups

Question 21

when is the AA protonated

Answer 21

low pH

Question 22

when is the AA deprotonated

Answer 22

high pH

Question 23

what is a zwitterion

Answer 23

COO- and NH3+. net charge zero

Question 24

when does the zwitterion occur

Answer 24

isoelectric point

Question 25

formula for isoelectric point

Answer 25

pI = (pk1 + pk2)/2

Question 26

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

Answer 26

salt

Question 27

what properties do AA have that are similar to a salt

Answer 27

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

Question 28

what occurs due to AA having 4 different substituents

Answer 28

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

Question 29

D or L?

Answer 29

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

Question 30

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

Answer 30

hyrgogen of alpha carbon

Question 31

7 categories of amino acids

Answer 31

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

Question 32

5 types of aliphatic AAs

Answer 32

glycine, alanine, valine, leucine, isoleucine

Question 33

defining feature of aliphatic AA

Answer 33

hydrophobic

Question 34

3 types of hydroxyl AA

Answer 34

serine, threonine, tryosine

Question 35

defining feature of hydroxyl AA

Answer 35

presence of OH group

Question 36

bonds that hydroxyl AAs make

Answer 36

h bonds diester links o-glycosidic links

Question 37

2 types of carboxyl AA

Answer 37

aspartic acid and glutamic acid

Question 38

defining feature of carboxyl AA

Answer 38

acidic. negative at pH7 | isoelectric point is

Question 39

bond that carboxyl AA can make

Answer 39

N-glycosidic link

Question 40

what form do carboxyl AAs show in their natural form

Answer 40

amide - NH2. aspargie and glutamine

Question 41

3 types of basic AA

Answer 41

histidine, lysine, arginine

Question 42

defining feature of basic AA

Answer 42

basic - positive at pH7. isoelectric point is >ph7

Question 43

what R group does histdine have

Answer 43

imidazole

Question 44

what reaction does lysine do

Answer 44

maillard

Question 45

what R group does arginine have

Answer 45

guanidine

Question 46

3 types of aromatic AA

Answer 46

phenylalanine tyrosine tryptophan

Question 47

which amino acid is in 2 groups

Answer 47

tyrosine

Question 48

defining feature of aromatic AA

Answer 48

presence of aromatic group - absorbs UV light

Question 49

what bonds can aromatic AA form

Answer 49

hydrophobic interactions

Question 50

3 sulfur contianing AA

Answer 50

cysteine and methionine. cystine - which is the cysteine dimer

Question 51

defining feature of sulfur AA

Answer 51

presence of a sulfur compound

Question 52

what bonds can sulfur AA undego

Answer 52

disulfide crosslinks

Question 53

what is a disulfide crosslink

Answer 53

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

Question 54

2 types of imino aicds

Answer 54

proline and hydroxyproline

Question 55

are iminoacids amino acids?

Answer 55

no - NH instead of NH2

Question 56

what structure does proline interfere with and why

Answer 56

alpha helix because its incapable of forming hydrogen bonds

Question 57

what increases as aliphatic AA chain lengthens

Answer 57

hydrophobicity

Question 58

what is a diester link

Answer 58

one phosphate group linked to 2 hydroxyl AA via ester linkages

Question 59

which is more acidic - aspartic or glutamic acid

Answer 59

aspartic

Question 60

what does MSG stand for

Answer 60

monosodium glutamate

Question 61

what reaction do carboxylic AA undergo

Answer 61

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

Question 62

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

Answer 62

amide. makes it more watersoluble

Question 63

is the sulfhydryl group acidic or basic

Answer 63

basic

Question 64

what type of proteins contain iminoAA

Answer 64

structural

Question 65

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

Answer 65

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

Question 66

when is a protein least soluble

Answer 66

when it's neutral at its isoelectric point

Question 67

how many essential AA

Answer 67

9

Question 68

what causes flavor from proteins

Answer 68

free AA and peptides

Question 69

what do protein hydrolases do in food

Answer 69

make meaty/broth flavor

Question 70

how do sulfur containing AA contribute to flavor

Answer 70

breaking down when heated releases H2S

Question 71

what is responsible for bitter flavors

Answer 71

peptides

Question 72

what is putrefaction

Answer 72

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

Question 73

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

Answer 73

false

Question 74

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

Answer 74

false

Question 75

A longer aliphatic chain in an AA will increase its…

Answer 75

hydrophobicity

Question 76

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

Answer 76

asymetric, chiral

Question 77

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

Answer 77

ph

Question 78

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

Answer 78

alpha carbon

Question 79

Coagulating milk casein is the main mechanism to produce

Answer 79

cheese

Question 80

True or false: proline is considered an alpha amino acid

Answer 80

false

Question 81

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

Answer 81

counterclockwise

Question 82

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

Answer 82

amphoteric

Question 83

Disulfide crosslinks result from the presence of … in amino acids

Answer 83

sulfhydryl (methionine doesn't form them)

Question 84

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

Answer 84

optical isomerism