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Human nutrition and physiology > Protein > Flashcards

Protein Flashcards

1
Q

According to NNR 2012 how much protein should an adult consume?

A

10-20 E%

corresponds to 0.8-1.5g protein/kg of bodyweight

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2
Q

According to WHO/FAO/UNU how much protein should an you consume?

A

0.66 g protein/kg of bodyweight –> 0.83 g protein/kg as

recommendation (based on nitrogen balance studies)

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3
Q

How many amino acids are there?

How many essential and non-essential

A

20 total

  • 9 essential
  • 11 non-essential
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4
Q

How many amino acid is a peptide and when does it become a protein?

A

<50 AA = peptide

>50 AA = protein

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5
Q

Which amino acids are essential (EAA)?

A 
Fenylalanin
isoleucine*
leucine *
Valine*
Methionine 
Treonine 
Tryptophan
Lysine 
Histidine
(*BCAA)
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6
Q

Which amino acids are non-essential

A 
Alanine
Arginine
Asparagine
Aspartic acid 
Cysteine
Glutamine 
Glutamic acid 
Glycine 
Proline
Serine 
Tyrosine
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7
Q

What kind of reaction occurs in a peptide bond formation?

A

Condensation reaction
or dehydration reaction
because of the release of a water molecule

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8
Q

What needs to be done in order for the proteins to be absorbed in the small intestine?

A

They need to be broken down to AA or alternatively dipeptides and oligopeptides

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9
Q

Digestion:

What happens in the stomach?

A

HCl denature protein because of the low pH

Pepsin starts degrading the protein into peptides (about 10-15% is degraded by pepsin)

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10
Q

Which digestive enzymes are produced by the pancreas?

A

Trypsin
Chymotrypsin
Elastase
Carboxypeptidase

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11
Q

What are brush border enzymes?

A

The microvilli that constitute the brush border have enzymes for the final part of digestion anchored into their apical plasma membrane as integral membrane proteins. These enzymes are found near to the transporters that will then allow absorption of the digested nutrients.

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12
Q

Brush border enzymes in digestion of proteins?

A

aminopeptidase

dipeptidase

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13
Q

What does trypsin do in protein digestion?

A

Trypsinogen is produced in pancrease - goes to the small intestine or duodenum and get’s activated into trypsin
starts cleaving polypeptides into peptides

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14
Q

The role of chymotrypsin in protein digestion?

A

is a digestive enzyme component of pancreatic juice acting in the duodenum, where it performs proteolysis, the breakdown of proteins and polypeptides. Chymotrypsin preferentially cleaves peptide amide bonds where the side chain of the amino acid C-terminal to the scissile amide bond (the P1 position) is a large hydrophobic amino acid (tyrosine, tryptophan, and phenylalanine). These amino acids contain an aromatic ring in their side chain that fits into a hydrophobic pocket (the S1 position) of the enzyme. It is activated in the presence of trypsin.

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15
Q

Role of elastase in protein digestion?

A 
Produced pancreas.
elastase is an enzyme from the class of proteases (peptidases) that break down proteins. In particular, it is a serine protease.
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16
Q

Role or Carboxypeptidase in protein digestion?

A

Produced pancreas
is a protease enzyme that hydrolyzes (cleaves) a peptide bond at the carboxy-terminal (C-terminal) end of a protein or peptide.

17
Q

What is important to be able to absorb proteins?

A

Need to break down proteins to AA to be absorbed

18
Q

Can dipeptide and tripeptides be absorbed?

A

Yes dipeptides and tripeptides can also be absorbed – but in the enterocyte they are converted into AA and then transported into the blood. (maybe some will be absorbed as they are)

19
Q

How are AA, tripeptides and dipeptides absorbed?

A

Through Enterocyte to blood

20
Q

How much energy is 1g of protein?

A

4 kcal

21
Q

Proteins in excess are used for…?

A

It is used to supply energy or build reserves of glucose, glycogen, or lipids.

22
Q

Why is nitrogen metabolism important?

A

Proteins make up the structural tissue for muscles and tendons, transport oxygen or hemoglobin, catalyze all biochemical reactions as enzymes, and regulate reactions as hormones. Our bodies must be able to synthesize the many proteins, amino acids, and other non-protein nitrogen containing compounds needed for growth, replacement, and repair.

23
Q

What is the “amino acid pool” what is the function and why do we need it?

A

The “nitrogen or amino acid pool” is a grand mixture of amino acids available in the cell derived from dietary sources or the degradation of protein. Since proteins and amino acids are not stored in the body, there is a constant turnover of protein. Some protein is constantly being synthesized while other protein is being degraded. For example, liver and plasma proteins have a half-life of 180 days or more, while enzymes and hormones may be recycled in a matter of minutes or hours.

24
Q

How many grams of protein are turned over/day?

A

300 grams

–> 3% turnover rate

25
Q

What can be used with the AA in the amino acid pool?

A

Anabolism: Produce body protein
Catabolism: AA broken down and form Urea, NH4+ and CO2
Synthesis of nitrogenous compounds as nucleotides, hormones and creatine

26
Q

What are protein requirements based on?

A

How much nitrogen you consume.

27
Q

Protein requirement can be catagorized into two categories, which and why?

A
  • Total nitrogen requirement (quantitative part)
  • Protein quality (Essential amino acids and enough of them)
    Gelatine for example is a protein, but can’t build muscle or any protein tissue with that molecule, because it is absent from one amino acid
  • It is therefore the minimum needed and if you consume less or with not good quality
    Then start to break down muscles, blown up stomach is a sign for protein efficiency
28
Q

What is the protein requirement (WHO/FAO/UNU)

and how much do you need if you weigh 80kg?

A

0,83g protein/kg bodyweight per day

80 x 0,83 = 66,4 grams of protein

29
Q

Give examples when there is a need for increased protein requirements

A
  • Total nitrogen requirement (quantitative part)
  • Protein quality (Essential amino acids and enough of them)
    Gelatine for example – is a protein, but can’t build muscle or any protein tissue with that molecule, because it is absent from one amino acid
    It is the minimum
    So if consume less or with not good quality
    Then start to break down muscles, blown up stomach is a sign for protein efficiency
30
Q

Epidemiological studies show an association between low-carb/highprotein diets and what?

A

type-2 diabetes however difficult to interpret

31
Q

What have intervention studies shown on higher protein intakes in healthy adults?

A

No harmful effect on kidney function or bone mass at higher protein intakes in healthy adults

32
Q

Satiety of protein vs carbs and fat?

A

More and longer satiety of protein

33
Q

What is the risk of focusing too much on protein in you diet?

A

It might lead to nutrient deficiency

34
Q

What did a meta-analysis of extra protein intake show?

A

That by consuming 1,6 g/kg you can increase muscle mass, which is healthy.
However larger effect in well-trained and less of an effect in the older population

35
Q

What happens during protein deficiency?

A 
• Breakdown of muscle tissue, muscle weakness and metabolic
disturbances
• Changes in skin and hair
• Effects on the immune system
• Impaired growth and development
• Effects on the cardiovascular system
• Edema and ascites
36
Q

Is protein deficiency common?

A

No hard having a protein deficiency whilst sustaining energy intake

37
Q

What is PEM (Protein-Energy Malnutrition)?

A

PEM is a term for all of the protein deficiency diseases.
– Kwashiorkor (protein deficiency)
– Marasm (energy deficiency)
– Marasmic kwashiorkor (combination of both)

38
Q

Why are BCAA important?

A

to stimulate the muscle synthesis

but for the the engine to fuel you need the other amino acids

Human nutrition and physiology (17 decks)

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