Advanced Nutrition Exam 3

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1

There are covalent linkages between amino acids called ________________ _____________ in synthesis of proteins

peptide bonds

2

all of the enzymes in the body cleave the ______________ ___________ for breaking down proteins

peptide bonds

3

The amino acid sequence is usually written from the ______-terminus to the _____-terminus, which is the same order as that in which amino acid residues are added to the peptide chain

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N-terminus to C-terminus (left to right)

-note: this means that the peptide bonds are made at the amino group (NH) end of one amino acid, and the carboxylic acid (OH group) of another amino acid

4

__________________ structures are defined as a linear sequence of amino acids in a polypeptide chain

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primary

(the amino acids in the polypeptide interact with each other to produce well-defined 3-D structure known as the native or folded state of the protein)

5

___________________ structures are formed through hydrogen bonds between backbone atoms

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secondary

-the backbone of polypeptide chain is highly polar whereas hydrophobic amino acids prefer to be on the inside of the protein

-the formation of hydrogen bonds between -NH and -C=O groups

-this includes both alpha and beta secondary structures

6

___________________ structures describes the overall 3-D arrangement of amino acids within a protein

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tertiary

-involves the formation of two or more structurally independent parts of the protein

7

_____________________ structures are defined as 3-D arrangements of multiple polypeptide chains

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quaternary

8

look at this

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9

quaternary proteins may be made up of identical or different polypeptide chains, called _________________ or __________________, which are held together by hydrophobic interactions, ionic, and hydrogen bonds

subunits or monomers

examples of quaternary structures include hemoglobin, insulin receptor, and myosin

10

the insulin receptor, for instance, contains _____ (#) alpha subunits and _____(#) beta subunits; thus this quaternary structure is what allows the insulin receptor to possess its function

2, 2

11

the __________________ and ___________________ structures establish the function of a protein

tertiary and quaternary

-primary and secondary structures do not provide function

12

Proteins act as ____________ balancers, which contribute to osmotic pressure in preventing fluids from escaping our blood vessels (ex: blood escaping into the interstitial space)

fluid

13

_________________ is one of the most important blood proteins in the body because it brings fluid back into the cells

albumin

14

_____________ is also known as hydrostatic pressure; this is when swelling occurs because fluid escapes the cell arteries

if you had an adequate amount of protein, though, the fluid will come back because the proteins provide the higher concentration to which the fluid is attracted (albumin and globulin are the main keepers of osmotic pressure)

edema

15

Proteins also act as _______________________, which means that these proteins play a role in immune function

the two main groups of these are:

immunoprotectors

immunoglobulins and antibodies, which are produced by B-lymphocytes

16

The two pathways for protein degradation (breaking down) are:

1) ubiquitin-proteasomal degradation

2) autophagy-lysosomal

17

describe the process of the ubiquitin proteasomal pathway:

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1) ubiquitin gets attached to the first enzyme/protein E1, which requires ATP

2) E1 brings the ubiquitin to E2 and transfers the ubiquitin to that E2

3) E2 (with the ubiquitin) binds to E3 (big protein), which binds to the protein targeted for degradation

4) E2 attaches the ubiquitin to the protein and leaves to pick up another ubiquitin from E1

5) E2 continues to attach ubiquitin to the protein until there is a chain of 5 ubiquitins, to which the protein ready for degradation is sent to the proteasol

18

in the autophagy-lysosomal pathway, the protein for degregation gets surrounded by a vesicle on the cell surface/inside the cell where the vesicle then gets fused with a ____________________ (this process is also known as endocytosis)

lysosome

19

lysosomes are __________________ cells organelles; they are present in all cells except RBCs

ubiquitous

20

lysosomes contain these two specific types of enzymes:

endopeptidases and exopeptidases (aka cathepsins)

21

lysosomes need an acidic pH in order to work; how does it accomplish this environment?

uses a proton pump on the lysosome membrane to bring H (hydrogen) ions inside the lysosome from the cytosol

22

the general amount of protein needs for people 19 and above is _________ g/kg/day

0.80 g/kg/day

23

for children 0 months-18 years, the protein needs are higher, ranging from 0.85- g/kg/day to 1.52 g/kg/day, with the highest proteins needs at __________ to 6 months

the protein needs are also higher for ___________________ and __________________ women

_________________ also need about 1.20 to 1.80 g/kg/day of protein, which is nearly 3x's the amount of a typical 19+ person

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birth

pregnant and lactating

athletes

24

nitrogen balance/status is important to figure out protein intake

nitrogen input = nitrogen ___________

protein contains __________% nitrogen

output

16%

25

Do the calculation:

how much nitrogen do we get from consumption of 80g of protein?

80g x 0.16 = 12.8g nitrogen

26

if someone needs 40 grams of nitrogen, how much protein do they need?

g (P) = N (g) x 6.25

40g x 6.25 = 250g protein

27

this type of brush boarder enzyme cleaves amino acids from the amino-terminal end (NH end) of oligopeptides: ________________________

aminopeptidases

-these really deal with the smaller amino acids; really only deal with the di- or tri- peptides

28

what do dipeptidyaminopeptidases do/produce?

they hydrolyze dipeptides and yield two free amino acids

29

what do tripeptidases do/produce?

they hydrolyze tripeptides and yield a free amino acid and a dipeptide

-some tripeptides may enter the intestinal cell intact; if you do happen to absorb di- or tri-peptides (happens sometimes), then the aminopeptodases in the brush boarder intestinal cells (in the cytosol) will further break down these peptides

30

aminopeptiadses cleave an amino acid on the ___________ end, while carboxypeptidases cleave from the ______________ end

amino

carboxyl

31
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______________________ (type of enzyme) hydrolyze internal peptide bonds within a polypeptide bond

endopeptidases

32
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______________________ (type of enzyme) cleave amino acids from either the carboxyl end (carboxypeptidases) or amino acid (aminopeptidases) end

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exopeptidases

33

which protease (protein-digesting enzyme) is produced by the stomach?

is it an endopeptidase or exopeptidase?

pepsin

endopeptidase

34

which proteases are produced by the pancreas? (5 of them)

know whether they are endopeptidases or exopeptidases

trypsin - endopeptidase

chymotrypsin - endopeptidase

elastase - endopeptidase

carboxypeptidase A - exopeptidase (at C-terminal end)

carboxypeptidase B - exopeptidase (at C-terminal end)

35

which proteases are produced by the intestinal cells?

know whether they are endopeptidases or exopeptidases

aminopeptidase - exopeptidase (at N-terminal end)

dipeptidylaminopeptidase - exopeptidase (at N-terminal)

tripeptidase - exopeptidase (at N-terminal)

36

true or false

the transport of peptides is more efficient than the transport of single amino acids

true

37

both dipeptides and tripeptides can be efficiently transported by this transport protein:

PET1, which is an apical membrane transporter located in the brush boarder (apical membrane) of the intestine

38

PET1 (aka PEPT1) requires the co-movement of peptides (di-/tri-) and ________________, specifically _______________

protons

H+ (hydrogen ions)

39

the ______ gradient across the enterocyte is what facilitates movement (more of this in the lumen than in the intestinal cell)

these ions (above answer) are pumped back into the lumen in exchange for _______ (another ion)

H+

Na+

40

Na+ gets pumped back out of the intestinal cell by the _________________ pump

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Na+, K+, ATPase pump

41

this process is the transfer of an amino group from an AA (amino acid) to an α-keto acid (AA carbon skeleton); thus, this process forms a different AA and a different α-keto acid every time

- this process is a reversible reaction

transamination

42

explain what happens when alanine aminotransferase (ALT) does its thing:

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ALT takes an amino group from alanine and transfers it to the alpha-keto acid (alpha-ketoglutarate), and the alanine now without the amino group becomes pyruvate (the carbon skeleton of alanine), and the alpha-ketoglutarate with the amino group becomes glutamate (the alpha amino acid)

43

explain what happens when aspartate amino-transferase (AST) does its thing:

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AST takes an amino group from aspartate and transfers it to the alpha-keto acid (alpha-ketoglutarate), and the aspartate without the amino group becomes oxaloacetate (the carbon skeleton of aspartate), and the alpha-ketoglutarate with the amino group becomes glutamate (the alpha amino acid)

44

________________ is the carbon skeleton of alanine

pyruvate

45

__________________ ___________ is the carbon skeleton of glutamate

alpha-keto acid

46

______________________ is the carbon skeleton of aspartate

oxaloacetate

47

__________________ is the removal of an amino group from AA by lyases, dehydratases or dehydrogenases (different enzymes depending on which amino acid is being deaminated)

deamination

48

commonly deaminated AAs are:

glutamate, histadine, serine, and glycine

49

the products of deamination are kind of similar to those of transamination in that they produce an alpha-keto acid, but they also produce _________________ instead glutamate (like transamination)

ammonia (NH3)

50

the _______________ ________ is favored in the body over ammonia (NH3) because of the body's pH, but this reaction can be reversed if need be for various needs in the body

ammonium ion (NH4)

51

the _____________ is the primary site of ammonia disposal

liver

ammonia is produced from deamination reactions (catabolism of amino acids) and needs to be disposed of quickly because it is toxic to the CNS

52

There are three major enzymes involved in ammonia disposal...

1) _________________ _____________________ produces glutamate by utilizing NADPH, +NH4, and alpha-ketoglutarate (don't forget alpha-ketoglutarate is the carbon skeleton of glutamate)

glutamate dehydrogenase

53

There are three major enzymes involved in ammonia disposal...

2) _________________ ___________________ produces glutamine by utilizing ATP, glutamate, and +NH4

glutamine synthase

54

There are three major enzymes involved in ammonia disposal...

3) _________________ ___________________ ___________________ ____ produces carbamoyl-PO4, which is sent to the urea cycle

carbamoyl phosphate synthetase (synthase) I

aka CPSI

55

the ammonia disposal process mainly happens in the liver, but where else does it occur?

muscles, etc.

56

why is ammonia so dangerous to the brain?

it is toxic to the CNS because the ammonia reacts with the alpha-ketoglutarate to form glutamate (through glutamate dehydrogenase reaction), which depletes the brain of alpha-ketoglutarate

- if all of the alpha-ketoglutamate is now being used to make glutamate in the brain, the TCA cycle cannot operate (because alpha-ketoglutarate is an intermediate in the TCA cycle), which ends up depleting the ATP in the brain

57

in patients with ______________ disease, ammonia is not properly disposed of, which results in intoxication thus leading to tremors, slurred speech, blurred vision, coma, and even death

liver

58

understand how the urea cycle works:

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1) start with carbamoyl phosphate synthese I (CPSI), which uses ammonia, ATP, CO2, and NAG (N-acetyl glutamate), which are all cofactors of CPSI to create carbamoyl-PO4

2) carbamoyl-PO4 and ornithine combine to make citruline

3) citruline and aspartate combine to make argininosuccinate

4) argininosuccinate is covered to arginine

5) arginine is broken down and ornithine is released to start the cycle again when it is combined with another carbamoyl-PO4

59

______________________ is the key molecule that regulates the urea cycle

N-acetylglutamate

60

____________ is the pacemaker enzyme of the urea cycle, but the activity is determined by levels of N-acetylglutamate

CPSI

61

since CPSI uses N-acetylglutamate as its co-factor, it depends on the amount of ________________________ that is present in the liver

N-acetylglutamate

62

_____________________ + ____________________ --> N-acetylglutamate

what enzyme does this?

acetyl coA + glutamate

N-acetylglutamate synthase

63

N-acetylglutamate can also be broken down...

N-acetylglutamate --> ____________________ + _____________________

what enzyme does this?

acetate + glutamate

N-acetylglutamate deacylase

64

After eating a meal, especially one high in protein, which enzyme is working the most?

N-acetylglutamate synthase to produce N-acetylglutamate, which causes upregulation of the urea cycle

65

tyrosine (a nonessential AA) is made from ____________________, which IS an essential AA and must be consumed

phenylalanine

-tyrosine is made from hydroxilation of phenylalanine by phenylalanine hydroxylase

*remember: TP

66

tyrosine is incredibly important in the body because it makes neurotransmitters and hormones, specifically ________________, _______________________, and _____________________

dopamine, norepinephrine, and epinephrine

- tyrosine also is important to make melanin and thyroid hormones

67

from methionine, you can make _________________ __________________ (______) by adding an adenosyl group to the methionine

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S-adenosyl methionine (SAM)

68

SAM is then converted to S-adenosyl homocysteine (_______) when the methyl group is transferred to a methyl acceptor

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SAH

69

SAH then gets hydrolyzed to form ____________________

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homocysteine

70

homocysteine can further be catabolized by ______________________ _______________ by combining homocysteine with serine to form ________________________

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cystathionine synthase

cystathionine

71

cystathionine can be converted into ________________ (a nonessential AA) by cystathionine lyase

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cysteine

72

cystathionine can also be further catabolized to produce products which ultimately end with forming _______________________ (which is a part of the TCA cycle)

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succinyl Co-A

73

to rid of excess homocysteine, there are two routes that homocysteine can take

1) ____________ can donate its methyl group to homocysteine to form methionine and a byproduct of glycine

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betaine

74

2) ______________________ can donate its methyl group to homocysteine to form methionine and the byproduct cobalamin

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methylcobalamin (vitamin B-12)

75

before methylcobalamin can be used for methionine production, ______________ has to donate its methyl group to vitamin B-12

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folate

76

remember, we make ________ in the body by adding an adenosyl group to methionine

SAM

77

________ is extremely important in the body because it is the principal methyl donor in the body; it methylates _________ in the body which affects gene expression (turns genes on and off)

SAM

DNA

78

SAM is also required for the synthesis of many compounds like:

carnitine, creatine, epinephrine, and melatonin

79

SAM promotes methionine catabolism, which is important because it prevents ____________________ buildup

homocysteine

80

high homocysteine levels are not good!! they have been associated with increased risk of:

-blood clots (coronary artery disease, stroke)

-dementia

81

causes of high homocysteine include:

-defects in cystathionine synthase

-vitamin B6 deficiency

-vitamin B12 deficiency

-folate deficiency

82

_________________ is an extremely important AA in the intestine because it serves as the primary source of energy for intestinal cells

glutamine

-glutamine also prevents atrophy of gut mucosa and bacterial translocation and is needed for mucin production in the intestine in along with theonine

83

glutamine synthesized by other tissues (especially the muscles) is also taken up by _________________ cells

intestinal

84

for the muscles, glutamine is a way to transport _________________ that comes from the transamination of BCAAs

ammonia

- BCAA (branched chain amino acid) transamination yields glutamate, so glutamine synthetase uses ammonia and glutamate to make glutamine

85

for the liver, in the fed state glutamine is used in the ___________ cycle

in the fasting state, glutamine is released into the blood for pickup by the kidneys for maintenance of ____________ ____________ balance

urea

acid base

86

for the kidneys, when the pH is acidic, glutamine is broken down by ___________________ into ammonia + glutamate

(the ammonia (NH3) can be turned into ammonia ions (+NH4) with the excess hydrogen ions [protons] in the kidneys, which can then be excreted as urea in the urine)

glutaminase

87

the _________________ metabolism in the intestine is key in order for the kidneys to metabolize the arginine that can be used by the other tissues in the body

arginine

88

about 40% of dietary _________________ is oxidized in the intestine with the formation of citruline

arginine

89

the kidneys pick up the ___________________ that was synthesized by the intestine for arginine synthesis for the other tissues

citruline

90

the cooperation between the _______________ and ________________ is incredibly important for arginine synthesis

kidneys and intestines

citruline is used to make arginine and arginine is used to make citruline.. both are in the urea cycle and depend on each other; arginine in kidneys (KA) and citruline in intestines (IC!)

91

since these two AAs depend on each other, if the intestines are injured, ________________ production may be impaired by the kidneys

arginine

-when injury like this occurs, arginine becomes a conditionally essential AA, and supplements with citrulline or arginine may be needed in the diet

92

the muscles can release _______________ during fasting

alanine

-an amino group from glutamate is transferred to pyruvate to make alanine (by ALT) in the muscle

93

the alanine made my the muscles gets sent to the ___________; here, the alalnine is converted back to __________________ for gluconeogenesis

this process as a whole is known as the ______________-_______________ cycle

liver

pyruvate

alanine-glucose cycle

94

what is the overall purpose of the alanine-glucose cycle?

it is really for the muscle to contribute by using amino acids to make glucose in the liver in the fasting situation

95

the skeletal muscles are catabolize ______________ ____________ amino acids at a high rate

why?

branched chain AAs

the muscles have a high concentration of the BC aminotransferases that are able to break down the BCAAs quickly, so that is where most of these BCAAs get catabolized; the liver does not have very many aminotransferases, which is why the activity is very low there and the liver bypasses the BCAAs

96

the _______________________ generated from the transamination reactions can also be decarboxylated by an enzyme called BCKAD (branched-chain alpha ketoacid dehydrogenase)

alpha-ketoacids

97

when there is a defect of BCKAD, it leads to ______________ ______________ _____________ which is from the excess excretion of alpha-letoacids in the urine

maple syrup urine (very distinct smell in urine)

98

the BCAAs have a variety of fates in regards to how they are used..

- valine's products are ____________________, so succinyl coA and isoleucine are used in gluconeogenesis

- isoleucine's products can be used in both the ___________________ and ___________________ pathways because the products are succinyl coA and acetyl coA

- leucine's products are strictly _____________________, because the product is acetyl coA

glucogenic

glucogenic and ketogenic

ketogenic

99

__________________ is one of the few amino acids that is completely oxidized by the muscle for energy (preferably during fasting)

leucine

100

_______________________ is a good indicator of muscle degradation because it cannot be reused in the body

3-methylhistidine

(once the methyl group is added to the histidine, it cannot be used to make protein anymore, thus its only fate is to be excreted)

-once again, it is a good indicator because we can tell how much muscle mass is being catabolized by observing the amount of 3-methylhistidine in the urine

101

the kidneys use _________________ and ______________ in maintenance of acid base balance

glutamine and glycine

102

in acidic conditions, glutamine and glutamate are deaminated in the kidneys yielding two ______________________

ammonias (one for each AA)

103

in the tubular lumen of the kidneys, the ammonias combine with _______ to form ammonium ions which are excreted via urine

H+ (protons)

104

glycine is also deaminated to form ____________________, which works in the same way to decrease the acidic environment

ammonia

105

the loss of H+ from these ammonium ions leads to a(n) _________________ (increase/decrease) in pH to a normal range (7.35 - 7.45)

increase

106

what is the role of acute phase proteins?

these proteins indicate that an acute phase response is occurring, which is a systematic response characterized by inflammation that can occur with metabolic stress

107

the _______________ acute phase is when these acute phase proteins are increased during metabolic stress

the _______________ acute phase is when these acute phase proteins are decreased during metabolic stress

- these increases/decreases are significant being at at least _____% of the individual's normal levels

positive

negative

25%

108

albumin is a __________________ acute phase protein

its half-life is _____-_____ days (after this many days it gets broken down and regenerated)

**longest half-life**

negative (this protein is suppressed under metabolic stress, which is why edema occurs)

18-21 days

109

transferrin is a __________________ acute phase protein

its half-life is _____-_____ days (after this many days it gets broken down and regenerated)

negative (this protein is suppressed under metabolic stress; because it transports iron, low iron status increases its concentration in the blood- more transferrin is produced so more iron can be transferring to the cells)

8-10 days

110

prealbumin is a __________________ acute phase protein

its half-life is _____-_____ days (after this many days it gets broken down and regenerated)

negative (this protein is suppressed under metabolic stress)

2-3 days

111

retinol-binding protein is a __________________ acute phase protein

its half-life is _____ hours (after this many hours it gets broken down and regenerated)

**shortest half-life**

negative (this protein is suppressed under metabolic stress)

12 hours

112

The positive acute phase proteins (proteins that are upregulated under metabolic stress) include:

C-reactive protein, orosomucoid, serum amyloid A, fibrinogen, haptoglobin, ceruloplasmin

113

are negative acute phase proteins good indicators of nutritional status?

why?

NO

-albumin, prealbumin,and transferrin do not seem to change with increased/decreased food intake

- even though proteins are not good for trying to figure out specific diseases, they are useful as indicators of morbidity and mortality and recovery from acute illness

- assessment of these proteins gives dietitians a means to identify the patients that are most likely to develop malnutrition

- a well-nourished but stressed patient may have low levels of these proteins whereas a patient with significant weight loss and undernutrition may have normal or close to normal levels.

114

___________________ acute phase proteins are released under conditions of metabolic stress

positive

115

metabolic stress is defined as a ________________________, catabolic state that occurs in response to sepsis, injury/trauma and some diseases (like cancer)

hypermetabolic

-example: in diseases like cancer, you lose weight really quickly because of the hypercatobolic state of breaking lots of things down in the body

116

under metabolic stress, __________________ are produced by immune system cells are released, which leads to an increase in levels of several hormones: glucocorticoids (cortisol), catecholamines, insulin, and glucagon

cytokines

- the release of cytokines can cause an increase in many different hormones; the boys really just goes insane because even hormones that are only supposed to be released at certain times, both are released like glycogen and insulin at the same time; everything goes HAYWIRE

117

a hallmark of metabolic stress is _____________________ because the body becomes resistant to insulin

hyperglycemia

even though insulin is around, with all of the cytokines around and glucagon producing even more glucose, the cells become insulin-resistant which is why hyperglycemia occurs

118

while ___________________ acute phase proteins are degraded by the proteasomal system, synthesis of ___________________ acute phase proteins is increased

negative

positive

119

this phenomenon is thought to occur due to the need to increase the synthesis of immune mediators over synthesis of other proteins not ____________________ to immune function

essential

120

Thank you Jesus

Amen