Biochemistry

Question 1

How is ammonia a potent neurotoxin?

Answer 1

Ammonia is bioreactive with aldehydes, and can alter behavior of proteins/gene materials

Question 2

The concentration of ammonia and ammonium ion in the blood is very (high/low)

Answer 2

Low

Question 3

(T or F) NH3 can easily diffuse through cell membranes

Answer 3

True

Question 4

Nitrogen is carried to the liver in the form of ____, _____, and _____.

Answer 4

Alanine, glutamine, and ammonia

Question 5

__% of Nitrogen waste is in urea to be excreted from the body. This helps to keep NH4+ and NH3 levels in the body low.

Answer 5

85%

Question 6

_______ and _______ reactions funnel amino groups in the urea cycle.

Answer 6

Transamination and de-amination reactions

Question 7

Carbamoyl phosphate synthetase I (CPS I) is located in the ______

Answer 7

Matrix of the mitochondria

Question 8

Ornithine reacts with carbamoyl phosphate to form ________

Answer 8

Citrulline

Question 9

Aspartate reacts with citrulline forming ________. Two “high energy” bonds are required.

Answer 9

Arginosuccinate

Question 10

Arginine and fumarate are formed from the cleavage of ___________.

Answer 10

Arginosuccinate

Question 11

Fumarate carbons can be converted into oxaloacetate by ________.

Answer 11

Transamination

Question 12

Arginine is cleaved into ______ and urea.

Answer 12

Ornithine

Question 13

Ornithine moves from the (cytosol/matrix) into the (cytosol/matrix)

Answer 13

Cytosol into the matrix

Question 14

Citrulline moves from the (cytosol/matrix) into the (cytosol/matrix)

Answer 14

Matrix into the cytosol

Question 15

Fumarate is a ______ intermediate

Answer 15

Krebs cycle

Question 16

Sources of Nitrogen for the Urea Cycle:

Ammonia is derived from oxidative deamination of _______ by ______ _________.

Answer 16

Glutamate by glutamate dehydrogenase

Question 17

Glutamate receives amino groups from amino acids through _________.

Answer 17

Transamination

Question 18

Glutamine and asparagine can donate _____ nitrogens.

Answer 18

Amide nitrogens

Question 19

Amine oxidases release ammonia from ______, ________, and _______.

Answer 19

Epinephrine, serotonin, and histamine

Question 20

Bacterial ureases act on amino acids in dietary protein and from urea diffusing into the gut with digestive fluids. Bacterial ureases convert urea in the intestinal fluids into ______ and _____.

Answer 20

NH3 and NH4+

Question 21

Forms of ammonia released by ureases is pH dependent. Charged (NH4+) (diffusible/non-diffusible) through tissue, and uncharged (NH3) and (diffusible/non-diffusible) through tissue.

Answer 21

NH4+ non-diffusible

NH3 diffusible

Question 22

At physiologic pH, (NH3 or NH4+) is produced, which is eliminated in the stool

Answer 22

NH4+

Question 23

Glutamine is synthesized from _______.

Using the enzyme glutamine synthase, (same answer) combines with ammonia, and ATP.

Answer 23

Glutamate

Question 24

When there is increased Nitrogen, N-acetylglutamate is the activator of ______, which provides short-term regulatory control.

Answer 24

CPS I

Question 25

A high protein diet or prolonged fasting (deactivates/activates) the urea cycle

Answer 25

Activates

Question 26

Hyperammonemia results from the inability to detoxify ____ in the urea cycle, leading to elevated blood levels of ammonia

Answer 26

NH4+ (Ammonium)

Question 27

Hereditary hyperammonemia results from defects in urea cycle _____.

Answer 27

Enzymes

Question 28

Acquired hyperammonemia most commonly occurs in ________ and ______ due to disruption of the urea cycle

Answer 28

Alcoholic cirrhosis and Reye's syndrome

Question 29

In _______, the architecture of the liver is distorted, leading to shunting of portal blood into the hepatic vein, or backup of blood in the portal vein (i.e., portal hypertension)

Answer 29

Cirrhosis

Question 30

In ________, the function of the urea cycle is disrupted by diffuse fatty changes in hepatocytes and damage to the mitochondria by salicylates.

Answer 30

Reye's Syndrome

Question 31

Reye's syndrome occurs primarily in ______ with _______ who are given salicylates

Answer 31

In children with influenza/chicken pox

Question 32

Sxs of hyperammonemia

Answer 32

Feeding difficulties, vomiting, ataxia, lethargy, irritability, poor intellectual development, coma. Death may result if sxs not treated.

Question 33

Non-pharm tx for hyperammonemia

Answer 33

Low-protein diet

Question 34

Renal Fuel Metabolism: | Glucose is mainly made by the cells of the _______

Answer 34

Renal medulla

Question 35

Renal Fuel Metabolism: The renal medulla: _______ glycolysis (no mitochondria) > Lactate

Answer 35

Anaerobic glycolysis

Question 36

Lactate is largely oxidized by the cells of the ________

Answer 36

Renal cortex

Question 37

The renal (cortex/medulla) is more metabolically active.

Answer 37

Renal cortex

Question 38

__________ is also a primary fuel of the kidneys in normal fasting conditions

Answer 38

Glutamine

Question 39

_______ serves as an amino group carrier from the kidneys. It carried nitrogens to the urea cycle, and is a precursor for gluconeogenesis.

Answer 39

Alanine

Question 40

Glycogen accumulates in the renal (cortex/medulla)

Answer 40

Renal medulla

Question 41

Cells of the medulla lack __________, cannot release glucose (no gluconeogenesis)

Answer 41

Glucose-6-phosphatase

Question 42

_______ cells possess full set of gluconeogenic enzymes. (gluconeogenesis in fasting state - do NOT store glucose)

Answer 42

Cortical

Question 43

_______ is the most important renal gluconeogenic substrate

Answer 43

Lactate

Question 44

In hypoglycemia, there is an (increase/decrease) in renal glucose release

Answer 44

Increase

Question 45

Renal glucose release in T2DM is (increased/decreased)

Answer 45

Increased

Question 46

Insulin (increases/suppresses) renal glucose release and | (increases/suppresses) glucose uptake.

Answer 46

Suppresses renal glucose release | Increases glucose uptake

Question 47

Insulin (increases/reduces) fatty acid uptake

Answer 47

Reduces

Question 48

Epinephrine (increases/decreases) renal gluconeogenesis

Answer 48

Increases

Question 49

GLUT2 is sodium (independent/dependent) and is the main protein for release of renal glucose into the circulation

Answer 49

Sodium independent

Question 50

SGLT2 is sodium (independent/dependent) and re-absorbs 90% of proximal tubular glucose

Answer 50

Sodium dependent

Question 51

GLUT1 transporters in the later segment change the affinity for glucose how?

Answer 51

Increase affinity in later segment because there is not much glucose left, and they want to be sure to capture all the glucose remaining.

Question 52

_________ is a basic amino acid at body pH, produced in the detoxification of ammonia

Answer 52

L-arginine

Question 53

Renal synthesis of arginine accounts for __% to ___% of endogenous supply

Answer 53

5% to 15%

Question 54

_______ is released from the small intestine and is the precursor for arginine synthesis

Answer 54

Citrulline

Question 55

Creatinine is a marker of _______ function

Answer 55

Kidney

Question 56

_______ is formed from phenylalanine

Answer 56

Tyrosine

Question 57

Half of the ______ in circulation derives from the kidneys

Answer 57

Tyrosine