Protein Requirements

Question 1

What is protein turnover?

Answer 1

• Cycle of protein synthesis and protein degradation

(when proteins wear our and must be replaced)

Question 2

What is the amino acid pool
and what is its source of
amino acids?

Answer 2

-Amino acids disbursed throughout the body and are available for protein synthesis.

-Comes from protein turnover and dietary protein

Question 3

how does Protein turnover it reduce the need
for dietary protein?

Answer 3

-Adapt to varying levels of nutrient availability (slower when less nutrients)
-makes sure new protein available for use (recovers proteins)

Question 4

Are all proteins recovered?

Answer 4

No, some lost to skin, hair, injury etc.

Question 5

What is Nitrogen Balance?

Answer 5

When nitrogen intake = nitrogen loss from the body

Question 6

What is classified as nitrogen intake and nitrogen loss?

Answer 6

intake = amino acids
loss = urea (mainly)

Question 7

Positive nitrogen balance? When does it occur?

Answer 7

-N intake > N loss

-Periods of growth (pregnancy, infancy, childhood, athletes)
-Recovering from
illness/body building/surgery (additional protein to replace protein loss)

Question 8

Negative nitrogen balance? When does it occur?

Answer 8

-N intake < N loss

-Starvation, dietary protein insufficiency, muscle atrophy
(trauma, chronic illness, carb insufficiency, aging)
-Sarcopenia - age related muscle loss/ loss of muscle function

Question 9

What do the following terms
mean: nitrogen balance,
positive nitrogen balance?
What conditions would you
expect each to occur?

Question 10

What element is used to
assess dietary protein
adequacy?

Question 11

What conditions would
require protein intake
beyond maintenance of
protein status?

Answer 11

Sickness, surgery, body building, growth, athletes

Question 12

What is sarcopenia?

Answer 12

Age related loss of muscle mass and muscle function

Question 13

What is the process of
deamination.

Answer 13

-Occurs in the liver -> Nitrogen containing amine group removed from carbon backbone
(Carbon skeleton (CHO) and amino group (N) part ways)

Question 14

When does deamination occur?

Answer 14

-When amino acids (C, H, O and N) are needed to synthesize glucose,

-When amino acids are in excess and converted to fatty acids (CHO)

Question 15

How does the body process
nitrogen when the amine
group is removed from the
amino acid?

Answer 15

1) Liver converts ammonia (waste) group to urea

2) Liver releases urea into blood

3) Kidneys filter urea out the blood

4) Urea excreted in urine

Question 16

What causes hepatic
encephalopathy and what
symptoms are present?

Answer 16

-Liver too diseased/damaged to convert ammonia to urea and ammonia accumulates in to blood - it circulates to the brain

Symptoms: Confusion, disorientation, memory loss, possible coma.

Question 17

What does it mean if a
protein is complete or
incomplete? What are the
dietary sources of each?

Answer 17

1) Complete: provides all essential amino acids in required amounts (animal proteins)

2) Incomplete: Lacking or has significantly low amounts of 1 or more amino acids (plant proteins)

Question 18

What is protein
complementation and what
does it accomplish?

Question 19

How can you get enough protein without a complete protein source? What is this called?

Answer 19

Consume a variety of incomplete proteins to provide complete protein source.

(protein complementation)