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NUTR 315 > Proteins (2/2) > Flashcards

Proteins (2/2) Flashcards

1
Q

What is the structure of protein?

A

amino acids, dipeptide, oligopeptide, and polypeptide

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2
Q

What are the levels of protein structure?

A

primary, secondary, tertiary, and quaternary

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3
Q

What are the essential amino acids?

A

isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, histidine

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4
Q

What are the nonessential amino acids?

A

alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, tyrosine

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5
Q

What is another name for essential amino acids?

A

indispensable

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6
Q

What is another name for nonessential amino acids?

A

dispensible

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7
Q

What are the functions of proteins?

A

growth & maintenance of tissues, essential metabolic compounds, transport of nutrients, regulation of water balance, maintenance of pH, defense & detoxification, energy (4 kcal/g)

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8
Q

What are examples of proteins?

A

enzymes, hormones, hemoglobin/myoglobin, apoproteins, transferrin/ferritin, antibodies, thrombin/fibrinogen/fibrin, and collagen

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9
Q

What are complete proteins?

A

contains all essential aa in sufficient quantities to support growth and is the first limiting amino acid

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10
Q

What is protein quality?

A

the spectrum of amino acids in food

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11
Q

Which is better, protein quality or quantity?

A

quality

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12
Q

What must proteins be broken down into to be absorbed?

A

amino acids, dipeptides, and tripeptides

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13
Q

What does protein digestion vary with?

A

the protein source

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14
Q

How does protein digestion occur in the stomach?

A

HCL denatures protein increasing access by enzymes and by pepsins which is secreted as pepsinogen and released controlled by gastrin (chewing)

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15
Q

What is the pH optimum for digestion of proteins in the stomach?

A

1.6-3.2

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16
Q

How does protein digestion occur in the small intestine?

A

partially digested food in duodenum causes release of cholecystokinin which stimulates secretion of proteolytic enzymes from the pancreas. smaller peptides digested further by enzymes secreted by intestinal mucosa

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17
Q

What are the endopeptidases?

A

trypsin, chymotrypsins, and elastase

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18
Q

What are the exopeptidases?

A

carboxypeptidase and aminopeptidase

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19
Q

What pancreatic enzyme works with enteropeptidase to form trypsin?

A

trypsinogen

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20
Q

What pancreatic enzyme works with trypsin to form chymotrypsins?

A

chymotrypsinogens

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21
Q

What pancreatic enzyme works with trypsin to form elastase?

A

proelastase

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22
Q

What pancreatic enzyme works with trypsin to form carboxypeptidase?

A

procarboxypeptidase

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23
Q

What are the intestinal proenzymes?

A

aminopeptidase and dipeptidase

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24
Q

Where are some di- and tripeptides transported?

A

into intestinal mucosal cells and hydrolyzed to amino acids

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25
Q

How are amino acids absorbed?

A

by active transport

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26
Q

Where do amino acids go once they enter the portal blood?

A

to the liver and other tissues

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27
Q

What does protein synthesis require?

A

adequate amounts of ALL amino acids

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28
Q

Where is genetic information held in cells?

A

in the DNA of genes in the nucleus

29
Q

What is transcription?

A

DNA code “copied” to mRNA and transferred from nucleus to cytoplasm

30
Q

What is translation?

A

mRNA “decoded” into a polypeptide by ribosome in cytoplasm

31
Q

What is tRNA needed for?

A

to deliver each aa as needed in translational process

32
Q

What are the steps in protein synthesis?

A

the DNA unwinds from its super-coiled state; unwinding allows the DNA code for the aa sequence to be transcribed into a complementary mRNA; the DNA stays in the nucleus and the mRNA travels to the cytosol; here the ribosomes read the codons on the mRNA and translate the instruction to produce a specific protein

33
Q

What is amino acid catabolism?

A

damination to yield C-skeleton and ammonia (NH4)

34
Q

What is the energy yield for amino acid catabolism?

A

4 kcal/g

35
Q

What are the fates of amino acid catabolism?

A

glucogenic (glucose) and ketogenic (acetyl CoA)

36
Q

How is nitrogen disposed in amino acid catabolism?

A

urea cycle

37
Q

What is the urea cycle?

A

ammonia is converted to urea in the liver by the liver removing ammonia from circulation and converts it to urea which is excreted from the kidney in urine

38
Q

What is nitrogen equilibrium?

A

nitrogen intake equals nitrogen excretion

39
Q

What is a situation when nitrogen equilibrium occurs?

A

healthy adult meeting protein and energy needs

40
Q

What is positive nitrogen balance?

A

nitrogen intake is greater than nitrogen excretion

41
Q

What are situations when positive nitrogen balance can occur?

A

growth, pregnancy, recovery stage after illness/injury, athletic training resulting in increased lean body mass, increased secretion of certain hormones, such as insulin, growth hormone, and testosterone

42
Q

What is negative nitrogen balance?

A

nitrogen intake is less than nitrogen excretion

43
Q

What are situations when negative nitrogen balance occurs?

A

inadequate intake of protein, inadequate energy intake, conditions such as fevers/buns/infxns, bed rest, deficiency of eaa, increased protein loss, increased secretion of certain hormones (thyroid hormone and cortisol)

44
Q

What percent of protein is nitrogen?

A

16%

45
Q

how can you convert g protein to g nitrogen?

A

multiply by 0.16

46
Q

how can you convert g nitrogen to g protein?

A

multiply by 6.25

47
Q

What is the EAR for protein?

A

0.66 g/kg*d

48
Q

What is the RDA for protein in females?

A

46 g/d

49
Q

What is the RDA for protein in males?

A

56 g/d

50
Q

What is the current intake of protein in the US?

A

65/95 g/d

51
Q

What is the concept about protein quality?

A

better quality then you have better retention and then better growth

52
Q

What measures are commonly used to look at protein quality?

A

biological value (BV), protein efficiency ratio (PER), chemical score, protein digestibility corrected amino acid score (PDCAAS)

53
Q

What is the formula for BV?

A

N retained/N absorbed x 100%

54
Q

How do you calculate N retained for the BV formula?

A

dietary N - (urinary N + fecal N)

55
Q

How do you calculate N absorbed for the BV formula?

A

(dietary N - fecal N)

56
Q

What BV is needed to support growth?

A

70+

57
Q

rank the following in order from largest to smallest BV: tofu, corn, fish, beef, rice, egg, milk

A

egg>milk>beef>fish>rice>tofu>corn

58
Q

What is the formula for PER?

A

weight gain (g)/dietary protein (g)

59
Q

Which has a higher PER, plant proteins or animal proteins?

A

animal proteins

60
Q

What is the formula for PDCAAS?

A

amount of each EAA in a protein/required amount of that EAA

61
Q

Rank the following from largest to smallest PDCAAS: egg, soy protein, milk, beef, blackbeans

A

egg>milk>soy protein>beef>black beans

62
Q

What is Kwashiorkor?

A

severe protein (with moderate energy) deficit; often accompanied by infections or other diseases

63
Q

What are characteristics of kwashiorkor?

A

edema, mild to moderate weight loss, maintenance of some muscle and subQ fat, growth impairment, rapid onset, fatty liver

64
Q

What is marasmus?

A

severe energy and protein deficit

65
Q

What are characteristics of marasmus?

A

severe weight loss, wasting of muscle and body fat, severe growth impairment, and develops gradually

66
Q

What are the different types of vegetarianism?

A

vegan, fruitarian, lactovegetarian, lactoovovegetarian, lactoovopollovegetarian, and pescovegetarian

67
Q

what are the nutritional consequences of vegetarianism?

A

few for normal/healthy adults; vegan most vulnerable; mainly for young, growing children and pregnant women; low in B12, Ca, vit D; bulk makes it difficult for children to get sufficient energy

68
Q

What is phenylketonuria (PKU)?

A

inborn error in metabolism that causes a person to miss phenylalanine hydroxylase which causes phenylalanine to accumulate in the blood and be excreted in urine. This interferes with neurotransmitter synthesis causing retardation

69
Q

What does phenylalanine hydroxylase do?

A

converts phenylalanine to tyrosine

NUTR 315 (22 decks)

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