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Food Chemistry > Proteins - after midterm > Flashcards

Proteins - after midterm Flashcards

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1
Q

which meat is the most important. That has played a significant role?

A

pork and beef

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2
Q

Is poultry included in the “meat”?

A

no

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3
Q

why almost all meat is consumed from young animals

A

because strenghthening of the muscles with time leads to tougher meat

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4
Q

The color of the meat is red to reddish pink why it is that

A

Myoglobin

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5
Q

red meat is mainly composed of what

A

skeletal muscle

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6
Q

What are other tissues that are associated with muscle’s physiological function?

A

bone, connective tissue, adipose tissue, nerves and blood

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7
Q

Meat composition will dependent on what

A

on the relative proportion of each type of tissue

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8
Q

what are the factots that affect the gross composition of re meat?

A

species, breed, sex, age, nutrition of the animal and the muscle condition

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9
Q

What are other factors that can be additioned when cuting meat?

A

anatomical location of the retail cut
extent of retail trim
methods of processing and cooking

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10
Q

In beef, pork and lamb what are the composition that composes most of their tissue. And in second, third, and 4th place

A

water
protein
lipid
ash

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11
Q

true or false

does meat has a lot of water

A

true

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12
Q

true or false

does meat has a lot of lipid

A

false

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13
Q

how is water found in the composition of the meat

A

they are either bound to proteins or free - trapped within muscle cells

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14
Q

how is protein analysed in meat

A

they are analyzed by the % of nitrogen content in the meat by doing a method called Kjeldahl analysis.
The % of nitrogen in the tissue is multiplied by 6.25 a factor that is based on the average of nitrogen amount

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15
Q

what is the method that we can do to calculate the amount of nitrogen in the meat

A

Kjeldahl analysis

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16
Q

true or false

the protein content of red meat is lower than usually reported

A

true

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17
Q

The values of the lipid that are stored in meat means what

A

The larger values indicated the prensence of variable amounts of neutral storage lipids

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18
Q

Wht there is a large variability in the % of lipid content

A

because the variability of lipid content is accounted by the variablity in water content

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19
Q

what is ash and what it does represent

A

it is the inorganic residue that remains after a muscle sample is incinerated at extremely high temperatures and it represent the mineral component of muscle

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20
Q

what is the main carbohydrate in meat

A

lactate

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21
Q

why the main carbs of meat is lactate

A

because it is in the muscle where it occurs the conversion of glycogen to lactate by anaerobic glycolysis

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22
Q

complete the sentence

However, the main carbohydrate in meat is …
because during conversion of muscle to meat the glycogen is
largely converted to lactate by … glycolysis.

A

lactate

anaerobic

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23
Q

Proteins in skeletal msucke can be separated based on their solubility into 3 classes, which are they?

A
  1. sarcoplasmic
  2. myofibrillar
  3. stromal
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24
Q

Which one of the classes (sarcoplasmic, myofibrillar, stromal) is

  1. Soluble
  2. insoluble
  3. concentrated in salt solution
A
  1. sarcoplasmic is soluble and 30% of total muscle
  2. stromal is insoluble and 10-20% of total muscle protein
  3. myofibrillar is concentrated in salt solution. 50-60% of total muscle proteins
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25
Q

Where is sarcoplasmic protein dissolved

A

cytoplasm (sarcoplasm ) inside the muscle cell

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26
Q

What are the proteins of the sarcoplasmic class and what are their function?

A

myoglobi and glycolytic enzymes. They regulate the cell and energy homeostasis

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27
Q

The colors f meat is associated with what

A

the oxidation state of the iron which is associated with myoglobin

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28
Q

Which animal as a paler color: young veal or an adult beef

A

young veal- they have less myoglobin

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29
Q

true or false

myofibrillar proteins constiture the largest fraction

A

true

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30
Q

Myofibrillar proeins can be concentarted in what

A

salt solutions

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31
Q

how is myofibrillar comports itself in the muscle tissue

A

because the muscle tissue has a high concentration of salt the myofibrillar is assembled into a compelx quternary structural filaments

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32
Q

what does a quaternary structural filaments do

A

it regulated, support perform the mechanical work of contraction

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33
Q

In the myofibrillar which protein is contractile

A

myosin and actin

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34
Q

what is the function of myosin and actin

A

myosin: muscle contraction in association with actin
actin: muscle contraction in association with myosin

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35
Q

what are the regulatory protein in myofibrillar proteins

A

troponin C, troponin I, troponin T and tropomyosin

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36
Q

what is the function of the TROPONIN COMPLEX (troponin C, troponin I, troponin T)

A

tromponin C: binds calcium
tromponin I :inhibits actin/myosin interaction
troponin T: binds the troponin complez to tropomyosin

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37
Q

what is the function of tropomyosin

A

binds actin and troponin

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38
Q

myosin anc actin together make for .. % of the total protein in skeletal muscle

A

40

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39
Q

Why the behavior of myofibrillar proteins is important in fresh meat?

A

because of the contraction and rigor mortis can be critical in the successful conversion of muscle to meat

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40
Q

What stromal proteins do

A

they form the fibrious connevtive tissues that strengthen and protect muscle - these insoluble proteins contribute to meat toughness

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41
Q

Complete the sentence:

… the most abundant protein in the animal body, is also the
most prevalent of the stromal proteins in muscle

A

collagen

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42
Q

what processing and cooking methods for meat do to collagen fibers?

A

theu are disrupt and partially solubilized

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43
Q

non protein nitrogen is made of what

A

creatine, amino acids, nucleic acids and nucleotides

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44
Q

What are the 2 sources of non-protien nutrogen that are key to the devlopment of rigor mortis

A

creatine and nucleotide ATP

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45
Q

complete the sentece

each myofiber is encased in a layer of connective tissue called

A

endomysium

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46
Q

groups of myofibers are organized into primary and secondary bundles of fascicles that are segregated by another layer of connective tissue called

A

perimysium

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47
Q

final layer is … it surround the whole muscle

A

epimysium

48
Q

the 3 layers of the muscle are

A

endomysium, perimysium and epimysium

49
Q

the perimysium and the endmysium combine to form what

A

to provide the necessary framework for maintaining the structural integrity of these tissues within the msucle

50
Q

What is embedded in the perimysium layer

A

adipose tissue

51
Q

if we see an aidpose tissue embedded in the perimysium in red meat what is the name

A

marbling

52
Q

how does muscle cells function

A

by translation of electrochemical impulses - triggered by neural simulation

53
Q

An increase in what ion will trigger muscle concentration?

A

calcium

54
Q

Myofibers are bound by what

A

plasma membrane

55
Q

what conducts the stimulus for contraction into the interior of the myofiber

A

T tubules

56
Q

T tubules are in contact with what? and what are their function?

A

they are in contact with SR (Sarcoplasmic Reticulum) which encircle the contractile organelles and function as a reservoir of calcium. They serve as a trigger of muscle contraction

57
Q

lysosome serve asa reservoir for a family of proteolytic enzymes known as

A

cathepsins

58
Q

what cathepsin do

A

play a catabolic function in protein turnover

59
Q

myofibers are typlically

a. 1 nucleous
b. 0 nucleus
c. multinucleated

A

c. multinucleated

60
Q

the sarcoplasm has 2 elements that will vary depending on the muscle fiber, nutrion and exercise. What are those 2 elements

A

glycogen and lipid

61
Q

1) complete:
the … storage protein myoglobin is found to varying
degrees within the sarcoplasm
2) what are also examples that can vary

A

1) oxygen

2) A.A, nucleotides, enzymes, etc

62
Q

what are the 3 types of myofibers?

A

type 1: slow red
type 2a: fast red
type 2b: fast white

63
Q

slow contracting red myofibers contains what

A

conain a lot of oxidative organelles and fuels like mitochondria, myoglobin and lipid

64
Q

fast contracting myofibers are more equipped for what

A

anaerobic metabolism fueled by carbs

65
Q

myofibrilis is what of the organelles of a muscle and what its his volume

A

it is the contractile organalle and constitute of 80-90% of the volume of the cell

66
Q

myofibrilis is composed of what

A

protein filaments in a highly specific structural organization

67
Q

wat is the fundamental structural unit of the myofribrils

A

sarcomere

68
Q

when you put a muscle under the microscope what do you see

A

A-bans and I-bans. They are anisotropic and isotropic

69
Q

what the A band constis of? and the I band ?

A

A-band consist of overlapping thin and thick fiaments while the I bands consist of thin filaments only

70
Q

The center of the A-band is brighter than the rest. What is the name of this part? and what this zone consist of

A

H zone it consists only of thick filaments with no overlapping thin filaments.

71
Q

Define sarcomere lengths and what is depend on?

A

definition: distance between adjacent Z-diss
dependent: on the satte of contraction of the myofiber on the stretch force applied to it

72
Q

during a contraction and resting state does both thin and thick filaments remain constant?

A

yes

73
Q

explain the shortening of the sarcomere lenght

A

thin filaments and thick
filaments interdigitate, allowing for sliding of filaments past each other. Thus, when contraction takes place, the thin and thick filaments
slide past each other such that the thin filaments at opposite
ends of a sarcomere move toward each other

74
Q

myofibrils is madeup of myofilament which is composed of what

A

myosin and actin

75
Q

what is the 2 functions of actin?

A

binds to myosin and binds to the regulatory proteins tropomyosin and troponin

76
Q

what is the function of tropomyosin?

A

exists in the myofiber as a head-to-tail

polymer

77
Q

what is the 3 subunits of troponin

A

troponin T
troponin C
troponin I

78
Q

What is nebulin

A

a large cytoskeletal protein associated with thin filaments

79
Q

what is the most abundant msucle protein

A

myosin

80
Q

what hapens during muscle at rest

A

When the muscle cell is at rest, tropomyosin sterically blocks
myosin heads from binding to the myosin-binding sites of the actin
filament.

81
Q

sarcoplasmic proteis include enzymes associated with glycolysis and glucogenolysis. What is the most abundant glycolytic enzyme?

A

glyceraldehyde phosphate dehydrogenase - over 20% of the total sarcoplasmic protein fraction

82
Q

what are the 5 most abundant sarcoplasmic proteins in muscle?

A

phosphoglucose isomerase

phosphofructokinase

glyceraldehyde phosphate

creatine kinase

adenylate kianse

83
Q

phosphorylase B is more abundant in ….. because these myofibers rely hevily on glycolysis for energy requirements

A

type II b myfibers

84
Q

myoglobin is present in greater abundance in … because they derive a greater share of their energy from oxidative metabolism.

A

type I myofibers

85
Q

How is AMP formed? and what is produced

A

AMP is formed by 2ADP-> ATP+ AMP

this happens after the animal dies. AMP will after form IMP and NH3

86
Q

IMP is further degraded to …, which imparts a bitter flavor to meat

A

hypoxanthine

87
Q

complete the sentence

Among the proteinases in muscle sarcoplasm, the calcium dependent proteinases known as … are of particular
interest in relation to the conversion of muscle to meat

A

calpain

88
Q

what is the role of calpain

A

convert muscle to meat. they breaj down particular proteins of the muofibril such as titin, nebulin and TnT during postmorde,

89
Q

what are the 3 types of calpain? and how they are activated

A

u calpain activated by micromolar concentration of calcium
m calpain activated by milimolar concentration of calcium
calpain 3 activated by submicromolar conc of ca

90
Q

which protein consist in stromal proteins

A

collagen (90%) and elastin (10%)

91
Q

where is collagen found

A

in connective tissues such a bone, tendons

92
Q

what is the basic unit of collagen

A

tropocollagen - constis of 3 polypeptide alpha chains

93
Q

type 1 collagen and type 3 collagen are made of what

A

type 1: 2 alpha chains of alpha 1 and 1 chain of alpha 2

type 3 collagen: 3 identical chains of alpha 1

94
Q

which amino acid is absent in collagen

A

tryptophan

95
Q

what is a common repeating sequence of A.A in collagen

A

glycine-proline,- hydroxyproline

96
Q

Glycine is the amino acid with the smallest possible “side chain”
(i.e., H) and thus is the only amino acid that could be
accommodated in the … of such a structure

A

interior

97
Q

… Fish sarcoplasmic proteins are mostly
enzymes. These enzymes correspond to those of mammalian
muscle tissue.

A

sarcoplasmic proteins

98
Q

connective tissue is lower in mammalian muscle or in fish

A

fish

99
Q

During bacterial decay of the flesh, a large

amount of … is formed from histidine

A

histamine

100
Q

ovalbumin

A

The major globular protein in albumen is ovalbumin. It
is a phosphoglycoprotein, with a molecular weight of about 44.5
kD

101
Q

… is the most easily heat-denatured egg protein but it

is less susceptible to surface denaturation than ovalbumin

A

ovotransferrin

102
Q

ovomocoid

A

is a glycoprotein consisting of three
tandem homologous domains, each cross-linked by three disulfide
bonds, with a total molecular weight of 28 kDa

103
Q

lysozyme

A

It is a bacteriolytic enzyme commonly found in nature that
catalyzes the hydrolysis of the glycosidic linkage between Nacetylmuraminic acid and N-acetylglucosamine in the
polysaccharides of certain bacterial cellwalls

104
Q

True or false. As the acidity increase the solubility decreased in soy protein

A

True

105
Q

What are the principle components of 2S, 7S, 11S and 15S

A

2S : alpha conglycinin
7S: beta conglycinin
11S: glycinin
15S: dimer of glycinin

106
Q

Which enzyme is responsible for rancidity in soybean oil and that leads to a bad smell

A

Lipoxygenase

107
Q

What is the 2 types of trypsin inhibitor

A

Kunitz and bowman-birk

108
Q

What is the function of hemagglutenins

A

Produce red blood cells

109
Q

What so the functional properties of soy protein

A

Emulsify, form gels, foams, thickens

110
Q

…. 65% to 85% protein content. Usually manufactured by using alcohol to remove the soluble carbohydrates from the oiled soy flakes.

… are produced using minimum heat and homogenization followed by spray drying or by water wash process at an acid ph

…protein content higher than 85%. It produces a bland flavour, light in colour and have a number of functional properties such as gelatin, emulsification, water holding, etc

A

Soy proteins concentrate

Functional soy concentrate

Soy protein isolate

111
Q

What is the major component of cereal protein

A

Starch

112
Q

What are the 2 major groups of gluten

A

Gluten in and gliadin

113
Q

Which bond glutenin has

A

Intermolecular disulphide bonds

114
Q

Which bonds gliadin has

A

Intramolecular disulphide bonds and SH groups

115
Q

When glutenin and gliadin are bound together, what happens

A

They form a dough/ elastic. The elasticity is due to the interaction of glutenin and gliadin and the S-S bonds and the S-H bonds. When you are kneading this reactions are formed and broken

Food Chemistry (11 decks)

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