Lecture 22 Flashcards

1
Q

What is de novo synthesis?

A

De novo synthesis is the synthesis of non-essential amino acids.

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2
Q

How is oxidation of amino acids measured?

A

Stable isotopes can be used to measure oxidation of amino acids using 13C labelled amino acids.

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3
Q

What results can be used to understand protein metabolism?

A

Ratio of 13CO2/12CO2 in breath and labelled/unlabelled amino acids in plasma.

More 13C in breath means more oxidation of infused tracer.

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4
Q

What happens to muscle protein synthesis during exercise?

A

Decrease of protein synthesis occurs during exercise.

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5
Q

What is the normal turnover rate in muscles? Is this a high value?

A

Turnover rate is typically 1-2% per day in muscles. This turnover is high in absolute terms due to amount of protein in muscle.

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6
Q

What happens during exercise and post exercise to explain the changes that occur in muscle size?

A

During exercise protein degradation is higher than protein synthesis but after exercise in resting periods protein synthesis increases significantly more than degradation rate.

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7
Q

How does endurance exercise affect untrained athletes?

A

Endurance exercise does not stimulate myofibrillar hypertrophy in untrained athletes but it does in trained athletes.

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8
Q

How does resistance training affect untrained athletes?

A

both myofibrillar and mitochondrial hyertrophy occurs in untrained athletes that do resistance training

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9
Q

How does endurance training affect trained athletes?

A

> mitochondrial hypertrophy

no change in myofibrillar hypertrophy

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10
Q

How can a muscle building stimulus increase protein synthesis?

A

Stimulus increases transcription of certain genes and mRNA.

improvement in translation efficiency can increase protein synthesis.

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11
Q

Why are Eif3s and Eif4s used when determinin muscle protein synthetic rate?

A

Eif3s and Eif4s are factors of translation initiation and researchers look for these to measure translation initiation.

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12
Q

What kind of effect does S6K1 have?

A

Effect of exercise on S6K1 is fibre-type specific. (Type 2 hypertophy)

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13
Q

Why does activity of the mTOR pathway decrease during exercise?

A

AMPK activity increases during exercise

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14
Q

What does rapamycin administration in humans do to skeletal muscle protein synthesis?

A

rapamycin administration in humans blocks contraction-induced increase in skeletal muscle protein synthesis.

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15
Q

Why does sarcopenia occur?

A

Protein synthetic response is reduced in elderly.

Aging causes a loss of muscle and increase in fat mass

activity of mTOR is essential for anabolic response to exercise and in elderly the effect of mTOR is decreased.

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16
Q

What happens to cancer patients after food intake?

A

The increase in protein synthesis after food intake is blunted in cancer patients.