Lecture 12

Question 1

What are the main functions of proteins?

Answer 1

Hormones

Enzymes

Proteins act as regulators of fluid balance.

Acid-Base regulators (attract hydrogen ions)

Transporters

antibodies

Energy source

Structural molecule

Question 2

1

Answer 2

Proteins are constantly broken down and produced. Amino acid pool is fairly constant.

Question 3

How is nitrogen excreted from the body?

Answer 3

Nitrogen is excreted as urea in urine.

Question 4

Can proteins contribute to weight gain? If so, how?

Answer 4

Yes, Protein can be converted into fat and in turn can contribute to weight gain.

Question 5

How is transamination carried out? What cofactor is required for this?

Answer 5

Deamination of amino acids forms ammonia and a keto acid. The ammonia molecule can be added to another keto acid and so this forms another amino acid. This is done with the help of vitamin B6.

Question 6

How is urea formed?

Answer 6

2 ammonia molecules combine with carbon dioxide to form urea.

Question 7

What organ produces urea? Where is urea excreted?

Answer 7

Liver releases urea into blood which is filtered out by kidneys.

Question 8

What is required when going on a high protein diet?

Answer 8

High requirement for water consumption in high protein diets.

Question 9

What are the potential entry sites for amino acids in the respiratory pathway?

Answer 9

converted to pyruvate

convrted to acetyl coa

enter tca cycle directly

Question 10

Can amino acids be converted into glucose?

Answer 10

amino acids can be converted to glucose from pyruvate via gluconeogenesis.

Question 11

What affects how much protein is required?

Answer 11

Quality of the protein influences how much is needed.

Question 12

What determines the quality of a protein?

Answer 12

digestibility: animal vs plant proteins.

Amino acid composition: Essential vs non essential, nitrogen containing amino groups. Limiting amino acid.

Question 13

What are reference proteins?

Answer 13

Reference proteins provide a standard for proteins and are typically a group of people which have above average requirements (eg. preschool-age children)

Question 14

What are complementary proteins?

Answer 14

Complementary proteins are different proteins that are low-quality that together provide a decent amount of amino acids.

Question 15

How are complementary proteins meant to be consumed?

Answer 15

complementary proteins are not necessary to be consumed at the same time provided they are consumed in a nearby time to each other (on the same day).

Question 16

How are amino acids scored?

Answer 16

Measuring quality of a protein and comparing the amino acid pattern with that of a reference protein.
eg. for every 3210 units of essential amino acids, 145 must be his, 340 Ile, 540 Leu. If the proteins limiting amino acid is 80% of the amount found in reference protien it is scored 80%.

Question 17

What is the disadvantage of using the reference protein system of amino acid scoring?

Answer 17

It doesn’t estimate digestability at all.

It’s blind to other things that may affect absorption.

Question 18

What does PDCAAS stand for?

Answer 18

Protein digestibility-corrected amino acid score.

Question 19

What does PDCAAS give?

Answer 19

Amino acid composition relative to reference protein. I.e amino acid score is found and multiplied by digestibility score to give PDCAAS for protein.

Question 20

What is biological value and how is it calculated?

Answer 20

Biological value is the efficiency of protein to support the body’s needs.

No protein is fed and nitrogen is measured. Protein is fed then measured.
Nretained/Nabsorbed *100= Biological Value

Question 21

What is the daily reguirement for protein?

Answer 21

Greater problems when dealing with malnutrition. %RDI is 0.84g/kg in males and 0.75g/kg in females.

Question 22

What are the health effects of protein deficiency?

Answer 22

Marasmus and kwashiorkor

Effect can be acute or chronic depends on type of deficiency

Energy malnutrition.

Question 23

What are the symptoms of kwashiorkor?

Answer 23

Edema

fatty liver

muscle wasting

apathy, sadness, irritability

Loss of apetite

Hair is dry and brittle

skin lesions

MEAL (malnutrition edema anemia liver (fatty liver))

Question 24

What are the symptoms of marasmum?

Answer 24

chronic

severe weight loss, muscle wasting, and no fat retention.

No edema or latty liver

hair is dry and brittle

skin is dry and easily wrinkled

good apetite

Question 25

What is the result of a combination of kwashiorkor and marasmus?

Answer 25

combination of marasmus and kwashiorkor can occur resulting in severe muscle wasting, infections, and edema. In this condition antibodies and haemoglobin are degraded.

Question 26

How is rehabilitation of kwashiorkor done?

Answer 26

rehabilitation from kwashiorkor and marasmus often require slow refeeding with 10% of kilojoules from protein.

Question 27

How is risk of heart disease affected by protein overconsumption?

Answer 27

Overconsumption of protein causes an increased risk of heart disease. This is a result of higher homocysteine levels and arginine levels.

Question 28

How is risk of cancer affected by protein overconsumption?

Answer 28

Protein rich foods associated with increase risk of cancer

Question 29

How is risk of osteoporosis affected by overconsumption of protein?

Answer 29

increase osteoporosis risk from overconsumption of proteins.

Question 30

How is the risk of kidney disease affected by higher protein levels in diet?

Answer 30

Kidney disease risk increases with higher protein levels due to higher urea excretion damage to kidney is exacerbated by protein excretion.

Question 31

RDI for protein:

Answer 31

10 to 35% of daily intake.

Males: 0.84 grams/kg
Females: 0.75 grams/kg

Question 32

What are the guidelines for daily intake?

Answer 32

Fat: 20-35%
Protein: 10-35%
CHO: 45-65%