Nitrogen Metabolism

Question 1

Nitrogen Balance

Answer 1

Nitrogen Balance = Intake - Excretion

Question 2

INTAKE > excretion

net accumulation of proteins as in growth and pregnancy

Answer 2

POSITIVE NITROGEN BALANCE

Question 3

Intake < EXCRETION

Net breakdown of protein as in surgery, advancd cancer, kwashiorkor or marasmus, starvation

Answer 3

NEGATIVE NITROGEN BALANCE

Question 4

Amino acids transfer their alpha amino group to alpha ketoglutarate –> glutamate
EXCEPTIONS: lysine, threonine, proline, hydroxyptoline

Answer 4

TRANSAMINATION

aminotransferase
pyridoxal phosphate - COENZYME

Question 5

AA that do NOT undergo transamination

Answer 5

Proline
Hydroxyproline
Threonine
Lysine

Question 6

Alanine Amino Transferase (ALT) or Serum Glutamate Pyruvate Transaminase (SGPT)

Answer 6

ALANINE + ALPHA KETOGLUTARATE —> PYRUVATE + GLUTAMATE

Question 7

Aspartate Amino Transferase (ALT) or Serum Glutamate Oxaloacetate Transaminase (SGOT)

Answer 7

ASPARTATE + ALPHA KETOGLUTARATE —> OAA + GLUTAMATE

Question 8

Removal of amino group from amino acid

Answer 8

OXIDATIVE DEAMINATION

in the LIVER and kidney glutamate is oxidatively deaminated to release ammonia

Question 9

In most tissues GLUTAMATE combines with AMMONIA to form GLUTAMINE

Answer 9

GLUTAMINE SYNTHETASE

Question 10

Glutamine is transported into the blood and may be deaminated to release ammonia in two organs

LIVER: in response to HIGH PROTEIN INTAKE

KIDNEYS: in response to METABOLIC ACIDOSIS

Answer 10

GLUTAMINASE

Question 11

The ammonia transporter from most tissues including the brain

Answer 11

GLUTAMINE

Question 12

The major end product of protein catabolism in the body

Answer 12

UREA

Question 13

Urea Cycle

Answer 13

LIVER

mitochondria and cytoplasm

Question 14

The ammonia transporter from muscles

Answer 14

ALANINE