Metabolism

Question 1

Which glycogen storage disease has glycogen phosphorylase deficiency?

Answer 1

Type 5 (McArdle’s disease)

Question 2

Which glycogen storage disease has glucose-6-phosphatase deficiency?

Answer 2

Type 1 (Von Gierke’s disease)

Question 3

Which glycogen storage disease has lactic acidosis, hyperlipidemia, hyperuricemia?

Answer 3

Type 1 (Von Gierke’s disease)

Question 4

Which glycogen storage disease has alpha-1,6-glucosidase deficiency?

Answer 4

Type 3 (Cori’s disease)

Question 5

Which glycogen storage disease has an alpha-1,4-glucosidase deficiency?

Answer 5

Type 2 (Pompe’s disease)

Question 6

Which glycogen storage disease has cardiomegaly?

Answer 6

Type 2 (Pompe’s disease) infantile type

Question 7

Which glycogen storage disease has diaphragm weakness -> respiratory failure?

Answer 7

Type 2 (Pompe’s disease) adult type

Question 8

Which glycogen storage disease has increased glycogen in the liver, sever fasting hypoglycemia?

Answer 8

Type 1 (Von Gierke’s disease)

Question 9

Which glycogen storage disease has hepatomegaly, hypoglycemia, hyperlipidemia (normal kidneys, lactate, and uric acid)

Answer 9

Type 3 (Cori’s disease)

Question 10

Which glycogen storage disease has painful muscle cramps, myoglobinuria with strenuous exercise?

Answer 10

Type 5 (McArdle’s disease)

Question 11

Which glycogen storage disease has severe hepatosplenomegaly and enlarged kidneys?

Answer 11

Type 1 (Von Gierke’s disease)

Question 12

What fuels are produced and used in the post absorptive period?

Answer 12

Glucose from liver glycogenolysis/ gluconeogenesis b/c there is no glucose left from your meal anymore.

Fatty acids from adipose tissue.

Brain, muscles and other tissue predominantly use glucose.

Question 13

When does gluconeogenesis begin in the post-absorptive period? When does it become fully active?

Answer 13

Begins 4-6 hours after last meals.

Fully active when glycogen stores are depleted (10-18 hours after last meal).

Question 14

How does the pattern of fuel production and usage change in early starvation (24 hours after last meal)?

Answer 14

Mainly gluconeogenesis (possibly a small amount of glycogenolysis).

Fatty acids from adipose tissue.

Brain predominantly uses glucose. Muscles and other tissues use some glucose some glucose but predominanly fatty acids. Brain and RBCs hog the glucose.

Question 15

In intermediate starvation (48 hours after the last meal) how does the pattern of fuel production and consumption change?

Answer 15

Produced: glucose from liver gluconeogenesis, fatty acids from adipose tissue, ketone bodies from the liver.

Used: brain uses predominantly glucose but also some ketone bodies. Muscles and other tissues use predominantly fatty acids but also some glucose and ketone bodies.

Question 16

What metabolic scenario favors the synthesis of ketone bodies?

Answer 16

Excess of acetyl CoA from fatty acid metabolism. When there is so much acetly CoA that it cant go thru TCA cycle, the rest of it will be broken down to ketone bodies.

Question 17

True or false. The ketone bodies can be used by all body tissues including the brain?

Answer 17

False. RBCs need glucose, everything else can use ketone bodies.

Question 18

What is the pattern of fuel utilization and production in prolonged starvation (5 days after last meal)?

Answer 18

Produced: glucose from liver gluconeogenesis, fatty acids from adipose tissue, ketone bodies from the liver.

Used: Brain uses predominantly ketone bodies. Muscles and other tissues use predominantly fatty acids and some ketone bodies. Whatever glucose is left will be used by RBCs.

Question 19

Comparing an overnight fast to a 3 day fast, what percentage of energy comes from glucose and from ketone bodies?

Answer 19

Overnight: 95% from glucose (2/3 from glycogen breakdown, 1/3 from gluconeogenesis). 5% from ketone bodies.

3 day fast: 60% from ketone bodies (1/2 are betahydroxybutarate, 1/2 acetoacetate). 40% from glucose (most from gluconeogenesis).

Question 20

What are the major regulatory enzymes of the citric acid cycle?

Answer 20

Citrate synthase (1st step), isocitrate dehydrogenase (rate limiting step). Alpha ketogluterate dehydrogenase (heavily regulate. Requires lots of coenzymes -> Tender loving care for nobody = Thiamine/ TPP, Lipoic acid, CoA, FAD, NAD)

Question 21

What is the rate limiting enzyme for glycolysis?

Answer 21

PFK1 (phosphofructokinase)

Question 22

What is the rate limiting enzyme for gluconeogenesis?

Answer 22

Fructose-1,6-bisphosphatase

Question 23

What is the rate limiting enzyme for citric acid cycle?

Answer 23

Isocitrate dehydrogenase

Question 24

What is the rate limiting enzyme for glycogenesis

Answer 24

Glycogen synthase

Question 25

What is the rate limiting enzyme for glycogenolysis?

Answer 25

Glycogen phosphorylase

Question 26

What is the functional role of S-adenosyl-methionine?

Answer 26

Transfers methyl (-CH3) groups. Used in the generation of phosphocreatine. Also important in the tetrahydrofolate, folic acid pathway. SAM is the methyl donor man. We use ATP and methionine to make SAM.

Question 27

What is the activated carrier for glucose?

Answer 27

UDP glucose

Question 28

What is the activated carrier for electrons?

Answer 28

FADH2 or NADH (or NADPH)

Question 29

What is the activated carrier for CO2?

Answer 29

Biotin

Question 30

What is the activated carrier for one-carbon units?

Answer 30

Tetrahydrofolate

Question 31

What is the activated carrier for acyl groups

Answer 31

CoA, lipoamide

Question 32

How many ATP are generated durng aerobic metabolism?

Answer 32

Malate shuttle -> 32 ATP. G3P shuttle -> 30 ATP. Anaerobic = 2 ATP + lactate molecule.

Question 33

What are the possible products of pyruvate?

Answer 33

Acetyl CoA with pyruvate dehydrogenase. Lactic acid, alanine or oxaloacetate.

Question 34

What are the irreversible enzymes involved in gluconeogenesis?

Answer 34

Pyruvate carboxylase, PEP carboxykinase, fructose-1,6-bisphosphatase (rate limiting step), glucose-6-phosphatase

Question 35

What is the primary energy source in a patient that has not eaten in 2 days.

Answer 35

Fatty acids

Question 36

What is the equation for Gibbs free energy?

Answer 36

change in G = change in H - Temp x change in S.

Question 37

**Arrange the following molecules from most exergonic with loss of phosphate to least exergonic with loss of pohosphate: adenosine monophosphate, adenosine triphosphate, phosphoenolpyruvate

Answer 37

PEP > ATP > AMP

Question 38

A stressed physician comes home from work, consumes 7 or 8 shots of tequila in rapid succession before dinner and becomes hypoglycemic. Why?

Answer 38

Generation of a lot of NADH from alcohol breakdown (both alcohol dehydrogenase and acetylaldehyde dehydrogenase create NADH) causing pyruvate to be made into lactate and oxaloacetate to be made into malate. This causes lack of substrates needed for gluconeogenesis. Less gluconeogenesis occurs and you become hypoglycemic.

Question 39

A woman commonly develops intense muscle cramps and darkening of her urine after exercise. What is her diagnosis?

Answer 39

McArdles disease (type V glycogen storage disease). Skeletal muscle glycogen phosphorlyase deficiency.

Question 40

What are the essential amino acids?

Answer 40

``` PVT TIM HALL Phenylalanine Valine Tryptophan Threonine Isoleucine Methionine Histadine Arginine Leucine Lysine ```

Question 41

What is the mechanism of action of lactulose?

Answer 41

Degrade by gut bacteria to acidify the GI tract and trap ammonium there (converts ammonia into ammonium anion). Also helps pull ammonium from the blood into the GI tract.

Question 42

What amino acid is a precursor to histamine?

Answer 42

Histadine

Question 43

What amino acid is a precursor to porphyrin, heme

Answer 43

Glycine

Question 44

What amino acid is a precursor to nitric oxide

Answer 44

Arginine

Question 45

What amino acid is a precursor to GABA

Answer 45

Glutamate

Question 46

What amino acid is a precursor to S-adenosyl methionine (SAM)?

Answer 46

Methionine

Question 47

What amino acid is a precursor to creatine?

Answer 47

Arginine

Question 48

Compare carbamoyl phosphate 1 to carbamoyl phosphate 2.

Answer 48

Carbamoyl phosphate 1- in mitochondria. Urea cycle. Nitrogen source = ammonium. Carbamoyl phosphate 2- in cytosol. Pyrimidine synthesis. Nitrogen source = glutamine

Question 49

Rate limiting enzyme of the urea cycle

Answer 49

Carbamoyl phosphate synthetase I (CPS I)

Question 50

Rate limiting enzyme of the hexose monophosphate pathway

Answer 50

Glucose 6 phosphate dehydrogenase

Question 51

Rate limiting enzyme of fatty acid synthesis

Answer 51

Acetyl CoA carboxylase

Question 52

Rate limiting enzyme of beta oxidation of fatty acids

Answer 52

Carnitine acyl transferase

Question 53

Rate limiting enzyme of ketone body synthesis

Answer 53

HMG CoA synthase

Question 54

Rate limiting enzyme of cholesterol synthesis

Answer 54

HMG CoA reductase

Question 55

Rate limiting enzyme of bile acid synthesis

Answer 55

7 alpha hydroxylase

Question 56

Rate limiting enzyme of heme synthesis

Answer 56

Aminolevulinate synthase

Question 57

What deficiency causes familial hypercholesterolemia?

Answer 57

LDL receptor

Question 58

A patient with PKU should have a diet low in phenylalanine. What other dietary modification should a patient with PKU make.

Answer 58

Increase dietary intake of tyrosine. Supplement BH4 (tetrahydrobiopterin) cofactor

Question 59

A full term neonate becomes mentally retarded and hyperactive and has a musty odor. What is the diagnosis?

Answer 59

PKU

Question 60

A two year old girl has an increase in abdominal girth, failure to thrive, and skin/ hair depigmentation. What is her diagnosis?

Answer 60

Kwashiorkor

Question 61

A middle aged man has dark spots on his sclera and has noted that his urine turns black when left sitting for a period of time. What is the diagnosis?

Answer 61

Alkaptonuria

Question 62

A patient has a genetic disease in which the treatment includes protein restriction to prevent mental retardation, ketoacidosis, and death. What is the diagnosis?

Answer 62

Maple syrup urine disease

Question 63

A 18 year old female has moderate generalized abdominal pain, normal WBC, and no fever. She has parasthesias in her lower extremities. What is her diagnosis?

Answer 63

Acute intermittent prophyria

Question 64

A 45 year old male alcoholic gets blistering lesions in sun exposed areas, especially the dorsum of the hands. He also has hypertrichosis of the face. What is the diagnosis?

Answer 64

Porphyria cutanea tarda

Question 65

What is the treatment for homocystinuria?

Answer 65

Decrease methionine and increase cystine in the diet. Increase B6, B12, and folate in the diet.