Biochemistry - Pulmonary / Renal Block (III)

Question 1

Amino acids whose citric acid cycle intermediates can be subsequently converted to ____________ are termed glucogenic as they are easily entered into gluconeogenesis.

Amino acids whose citric acid cycle intermediates can be subsequently converted to ____________ are termed ketogenic as they are easily entered into fatty acid or ketone synthesis.

Amino acids whose citric acid cycle intermediates can be subsequently converted to ____________ are termed both glucogenic and ketogenic as they are easily entered into both of the above pathways.

Answer 1

Oxaloacetate;

acetyl-CoA;

pyruvate

Question 2

Amino acids whose citric acid cycle intermediates can be subsequently converted to pyruvate are termed ___________.

Amino acids whose citric acid cycle intermediates can be subsequently converted to oxaloacetate are termed ___________.

Amino acids whose citric acid cycle intermediates can be subsequently converted to acetyl-CoA are termed ___________.

Answer 2

Both ketogenic and glucogenic;

glucogenic;

ketogenic

Question 3

Which are the amino acids that are solely ketogenic (2)?

What does this mean?

Answer 3

Leucine, lysine;

they are easily converted to acetyl-CoA

Question 4

Which are the amino acids that are solely glucogenic (9)?

What does this mean?

Answer 4

Arginine

Asparagine & Glutamine

Aspartate & Glutamate

Histidine

Methionine

Proline

Valine;

they are easily converted to oxaloacetate

Question 5

Which are the amino acids that are either ketogenic or glucogenic (9)?

What does this mean?

Answer 5

Alanine

Cysteine

Glycine

Isoleucine

Phenylalanine

Serine

Threonine

Tryptophan

Tyrosine;

they are readily converted to pyruvate (which is easily convertible to acetyl-CoA and oxaloacetate)

Question 6

Decide (for each AA individually) if each of the following amino acids is ketogenic, glucogenic, or both:

Proline

Tryptophan

Serine

Valine

Methionine

Answer 6

Glucogenic

Both

Both

Glucogenic

Glucogenic

Question 7

Decide (for each AA individually) if each of the following amino acids is ketogenic, glucogenic, or both:

Threonine

Histidine

Lysine

Isoleucine

Glutamine

Answer 7

Both

Glucogenic

Ketogenic

Both

Glucogenic

Question 8

Decide (for each AA individually) if each of the following amino acids is ketogenic, glucogenic, or both:

Glutamate

Aspartate

Phenylalanine

Asparagine

Aspartate

Answer 8

Glucogenic

Glucogenic

Both

Glucogenic

Glucogenic

Question 9

Decide (for each AA individually) if each of the following amino acids is ketogenic, glucogenic, or both:

Arginine

Cysteine

Leucine

Tyrosine

Glycine

Answer 9

Glucogenic

Both

Ketogenic

Both

Both

Question 10

Any amino acid that can be converted to (1) _________ is termed both glucogenic and ketogenic because (1) can be converted both to (2) _________ and (3) _________.

(Note: not all AA that are both glucogenic and ketogenic can be converted to (1). Some can enter the citric acid cycle at multiple intermediates.)

Answer 10

(1) Pyruvate,
(2) acetyl-CoA, (3) oxaloacetate

Question 11

What are the (1) buildup product(s) and (2) deficient enzyme of homocystinuria?

Answer 11

Homocysteine (and possibly methionine);

cystathione β-synthase

Question 12

What are the (1) buildup product(s) and (2) deficient enzyme of maple syrup urine disease?

Answer 12

Branched-chain ketoaciduria;

branched-chain α-ketoacid dehydrogenase complex

Question 13

What are the (1) buildup product(s) and (2) deficient enzyme of methylmalonic acidemia?

Answer 13

L-Methylmalonic acid (and possibly propionyl-CoA);

methylmalonyl-CoA mutase

Question 14

What are the (1) buildup product(s) and (2) deficient enzyme of phenylketonuria?

Answer 14

Phenylalanine;

phenylalanine hydroxylase

Question 15

What are the (1) buildup product(s) and (2) deficient enzyme of alkaptonuria?

Answer 15

Homogentisate;

homogentisate oxidase

Question 16

What are the (1) buildup product(s) and (2) deficient enzyme of type I tyrosinemia?

Answer 16

Fumarylacetoacetate;

fumarylacetoacetate hydrolase

Question 17

What are the (1) buildup product(s) and (2) deficient enzyme of type II tyrosinemia?

Answer 17

Tyrosine;

tyrosine aminotransferase

Question 18

What inborn error of metabolism is associated with a buildup of homocysteine (and possibly methionine)?

What enzyme is deficient?

Answer 18

Homocystinuria;

cystathione β-synthase

Question 19

What inborn error of metabolism is associated with a buildup of branched-chain α-ketoacids?

What enzyme is deficient?

Answer 19

Maple syrup urine disease;

branched-chain α-ketoacid dehydrogenase complex

Question 20

What inborn error of metabolism is associated with a buildup of L-methylmalonic acid?

What enzyme is deficient?

Answer 20

Methylmalonic acidemia;

methylmalonyl-CoA mutase

Question 21

What inborn error of metabolism is associated with a buildup of phenylalanine?

What enzyme is deficient?

Answer 21

Phenylketonuria;

phenylalanine hydroxylase

Question 22

What inborn error of metabolism is associated with a buildup of homogentisate?

What enzyme is deficient?

Answer 22

Alkaptonuria;

homogentisate oxidase

Question 23

What inborn error of metabolism is associated with a buildup of fumarylacetoacetate?

What enzyme is deficient?

Answer 23

Type I tyrosinemia;

fumarylacetoacetate hydrolase

Question 24

What inborn error of metabolism is associated with a buildup of tyrosine?

What enzyme is deficient?

Answer 24

Type II tyrosinemia;

tyrosine aminotransferase

Question 25

Phenylketonuria is basically an inability to convert ____________ to \_\_\_\_\_\_\_\_\_\_\_. Why does this affect neurotransmitter production?

Answer 25

Phenylalanine, tyrosine; tyrosine is a precursor for catecholamine synthesis

Question 26

Asides from a phenylalanine hydroxylase deficiency (the most common cause), what other issues might cause phenylketonuria?

Answer 26

(1) A deficiency of tetrahydrobiopterin (BH₄) *(a cofactor for phenylalanine hydroxylase and catecholamine synthesis)*; (2) an inability to regenerate BH₄ from BH₂ *(via dihydropteridine reductase)*

Question 27

A 45-year-old male presents with complaints of worsening arthralgias. Upon further studies, you note that his urine turns brown when left exposed to air. What is at the top of your differential? What deficiency is responsible?

Answer 27

Alkaptonuria; the enzyme homogentisate oxidase

Question 28

How is maple syrup urine disease managed?

Answer 28

Via restriction of branched-chain amino acids (valine, isoleucine, leucine)

Question 29

What substrate may build up in cases of severe B12 deficiency, causing acidemia? This is because a certain enzyme involving acids requires B12 as a cofactor. Which is it? This is an alternate cause of what type of acidemia?

Answer 29

L-Methylmalonic acid; methylmalonyl-CoA mutase; methylmalonic acidemia

Question 30

What are the two major methyl donors in the body?

Answer 30

S-Adenosylmethionine; folate (and its derivatives)

Question 31

What two vitamins are needed for S-adenosylmethionine (SAM) (a methyl donor) regeneration? After donating its methyl group, SAM becomes S-adenosylhomocysteine, then homocysteine, then methionine. In which part of this chain are the two vitamins necessary?

Answer 31

B12 and folate; the conversion of homocysteine to methionine

Question 32

After donating its methyl group, S-adenosylmethionine (SAM) becomes S-adenosylhomocysteine, then homocysteine. What are the two products that are typically now produced from homocysteine? Which vitamins are required for each path?

Answer 32

Either: (1) methionine (to regenerate SAM), **B12** **and folate**; or (2) cystathione, **B6** (pyridoxal phosphate)

Question 33

Methylmalonyl-CoA can be created from the metabolism of propionyl-CoA. It is then often converted to _____________ to enter the citric acid cycle. What enzyme and vitamin are involved in this conversion?

Answer 33

Succinyl-CoA; methylmalonyl-CoA mutase, B12

Question 34

A deficiency of which of the following can cause an elevation in blood homocysteine: **vitamin B12, vitamin B6,** **or folate**? A deficiency of which of the following can cause an elevation in blood L-methylmalonic acid: **vitamin B12, vitamin B6,** **or folate**?

Answer 34

All three; B12 only

Question 35

What acid often builds up in addition to L-methylmalonic acid?

Answer 35

Propionic acid

Question 36

If poorly controlled, which of the following inborn errors of metabolism are most likely to cause intellectual disability and other neurological disabilties? **Alkaptonuria** **Type I tyrosinemia** **Type II tyrosinemia** **Phenylketonuria** **Homocystinuria** **Maple syrup urine disease** **Methylmalonic acidemia**

Answer 36

Type II tyrosinemia Phenylketonuria Homocystinuria Maple syrup urine disease Methylmalonic acidemia

Question 37

How does type I tyrosinemia often present?

Answer 37

A cabbage-like odor in the urine; liver failure, renal tubular acidosis

Question 38

Which are the \*conditionally essential amino acids (6)? *(\*E.g. essential during growth, pregnancy, illness, etc.)*

Answer 38

Arginine Cysteine Glutamine Glycine Proline Tyrosine

Question 39

Which are the nonessential amino acids (5)?

Answer 39

Alanine Asparagine Aspartate Glutamate Serine

Question 40

State if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Alanine**

Answer 40

Nonessential; both; pyruvate

Question 41

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Arginine**

Answer 41

Conditionally essential; glucogenic; α-ketoglutarate

Question 42

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Asparagine**

Answer 42

Nonessential; glucogenic; oxaloacetate

Question 43

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Aspartate**

Answer 43

Nonessential; glucogenic; oxaloacetate

Question 44

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Cysteine**

Answer 44

Conditionally essential both; pyruvate

Question 45

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Glutamine**

Answer 45

Conditionally essential; glucogenic; α-ketoglutarate

Question 46

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Glutamate**

Answer 46

Nonessential; glucogenic; α-ketoglutarate

Question 47

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Glycine**

Answer 47

Conditionally essential; both; pyruvate

Question 48

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Histidine**

Answer 48

Essential; glucogenic; α-ketoglutarate

Question 49

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Isoleucine**

Answer 49

Essential; both; succinyl-CoA, acetyl-CoA

Question 50

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Leucine**

Answer 50

Essential; ketogenic; acetyl-CoA, acetoacetate

Question 51

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Lysine**

Answer 51

Essential; ketogenic; acetoacetate

Question 52

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Methionine**

Answer 52

Essential; glucogenic; succinyl-CoA

Question 53

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Phenylalanine**

Answer 53

Essential; both; fumarate, acetoacetate

Question 54

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Proline**

Answer 54

Conditionally essential; glucogenic; α-ketoglutarate

Question 55

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Serine**

Answer 55

Nonessential both; pyruvate

Question 56

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Threonine**

Answer 56

Essential; both; succinyl-CoA. acetyl-CoA

Question 57

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Tryptophan**

Answer 57

Essential; both; pyruvate, acetoacetate, acetyl-CoA

Question 58

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Tyrosine**

Answer 58

Conditionally essential; both; fumarate, acetoacetate

Question 59

First, state if the following amino acid is essential, conditionally essential, or nonessential. Second, state if the following amino acid is glucogenic, ketogenic, or both. Third, name the citric acid cycle intermediate(s) into which it is readily convertible. **Valine**

Answer 59

Essential; glucogenic; succinyl-CoA

Question 60

What enzyme can convert aspartate and α-ketoglutarate to oxaloacetate and glutamate? What enzyme can interconvert glutamate and α-ketoglutarate?

Answer 60

Aspartate aminotransferase (AST); glutamate dehydrogenase

Question 61

What enzyme can convert glutamate to glutamine? What enzyme can convert glutamine to glutamate?

Answer 61

Glutamine synthetase; glutaminase

Question 62

What enzyme can interconvert alanine and pyruvate? What enzyme can interconvert aspartate and oxaloacetate?

Answer 62

Alanine aminotransferase (ALT); aspartate aminotransferase (AST)

Question 63

What enzyme can convert aspartate to asparagine? What enzyme can convert asparagine to aspartate?

Answer 63

Asparagine synthetase; asparaginase

Question 64

In the Cahill cycle, what molecule travels from the muscle to the liver to boost gluconeogenesis? In the Cori cycle, what molecule travels from the muscle to the liver boost gluconeogenesis?

Answer 64

Alanine; lactate

Question 65

The Cahill cycle increases liver gluconeogenesis in times of \_\_\_\_\_\_\_\_\_\_\_\_. The Cori cycle increases liver gluconeogenesis in times of \_\_\_\_\_\_\_\_\_\_\_\_.

Answer 65

Starvation; hypoxia

Question 66

Epinephrine, norepinephrine, and dopamine are synthesized from what common precursor?

Answer 66

Tyrosine

Question 67

Starting with tyrosine, what is the order of intermediates and products in catecholamine synthesis?

Answer 67

Tyrosine --\> **DOPA** --\> **Dopamine** --\> **Norepinephrine** --\> **Epinephrine**

Question 68

GABA is made from what immediate precursor? Histamine is made from what immediate precursor? Serotonin is made from what precursors?

Answer 68

Glutamate; histidine; tryptophan, then 5-HT

Question 69

Which neurotransmitters require pyridoxal phosphate (B6 derivative) for their synthesis?

Answer 69

Dopamine (from DOPA); GABA (from glutamate); histamine (from histidine); serotonin (from 5-HT)

Question 70

What cofactors are needed for the synthesis of DOPA from tyrosine? What cofactors are needed for the synthesis of epinephrine from norepinephrine? What cofactors are needed for the synthesis of norepinephrine from dopamine?

Answer 70

Tetrahydrobiopterin (BH₄; aka **Kuvan**); vitamin C and copper (Cu²⁺); vitamin B₁₂, folate, S-adenosylmethionine

Question 71

Why are Parkinsons patients treated with both L-DOPA *and* carbidopa? *(Hint: L-DOPA stimulates dopamine production in both the CNS and PNS.)*

Answer 71

Carbidopa inhibits PNS dopamine production, limiting the L-DOPA-driven increase in dopamine production to just the CNS

Question 72

What are porphyrias?

Answer 72

Rare disorders of heme synthesis

Question 73

Which is the most common porphryia?

Answer 73

Cutanea tarda

Question 74

Which porphryia does _not_ cause a sensitivity to light?

Answer 74

Acute intermittent porphyria

Question 75

Which porphyrias are hepatic?

Answer 75

Cutanea tarda (both erythropoeitic and hepatic); acute intermittent; hereditary coproporphyria; variegate

Question 76

Which substrate sometimes produced in porphyrias can produced skin photosensitivity?

Answer 76

Uroporphyinogen I

Question 77

Which porphyrias are erythropoeitic?

Answer 77

Cutanea tarda (both erythropoeitic and hepatic); congenital erythropoeitic; erythpoeitic protoporphyria

Question 78

Name the enzyme defect and buildup product for the following porphyria: ## Footnote **Acute intermittent porphyria**

Answer 78

Hydroxymethylbilane synthetase; porphobilinogen & δ-ALA

Question 79

Name the enzyme defect and buildup product for the following porphyria: ## Footnote **Congenital erythropoeitic porphyria**

Answer 79

Uroporphyrinogen III synthase; uroporphyrinogen I & coproporphyrinogen I

Question 80

Name the enzyme defect and buildup product for the following porphyria: ## Footnote **Cutanea tarda porphyria**

Answer 80

Uroporphyrinogen decarboxylase; uroporphyrin

Question 81

Name the enzyme defect and buildup product for the following porphyria: ## Footnote **Hereditary coproporphyria**

Answer 81

Coproporphyrinogen oxidase; coproporphyrinogen III

Question 82

Name the enzyme defect and buildup product for the following porphyria: ## Footnote **Variegate porphyria**

Answer 82

Protoporphyrinogen oxidase; protoporphyrinogen IX

Question 83

Name the enzyme defect and buildup product for the following porphyria: ## Footnote **Erythropoeitic protoporphyria**

Answer 83

Ferrochetalase; protoporphyrin

Question 84

What is the rate-limiting step of heme synthesis?

Answer 84

ALA synthase forms δ-ALA

Question 85

Which steps of heme synthesis are inhibited by lead poisoning? ## Footnote *(Which enzymes are involved?)*

Answer 85

The 2nd step and the final step ## Footnote *(ALA dehydratase & ferrochetalase)*

Question 86

Describe the functions of the spleen and the liver in bilirubin metabolism.

Answer 86

**1.** Splenic macrophages **destroy senescent erythrocytes**, releasing bilirubin **2.** Unconjugated bilirubin is carried to the liver by albumin **3.** The liver **conjugates** the bilirubin with **glucuronic acid**

Question 87

After the spleen destroys senescent RBCs, bilirubin forms, and the liver conjugates that bilirubin with \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_, what happens next (as far as elimination of the bilirubin from the body)?

Answer 87

Glucuronic acid; **1.** The conjugated bilirubin is secreted into the duodenem in **bile** **2.** The intestinal flora deconjugates the bilirubin and converts it to **urobilinogen** **3.** This urobilinogen either remains in the gut and is secreted in feces as **stercobilin** or reabsorbed and secreted in the urine as **urobilin**

Question 88

The liver enzyme ___________ \_\_\_\_\_\_\_\_\_\_\_ conjugates bilirubin with __________ \_\_\_\_\_\_\_\_\_\_ to form __________ \_\_\_\_\_\_\_\_\_\_ (conjugated bilirubin).

Answer 88

Bilirubin glucuronyltransferase; glucuronic acid; bilirubin diglucuronide

Question 89

What form of bilirubin is most elevated in the blood in cases of hemolytic jaundice?

Answer 89

Unconjugated

Question 90

What form of bilirubin is most elevated in the blood in cases of obstructive jaundice?

Answer 90

Bilirubin diglucuronide (conjugated bilirubin)

Question 91

What form of bilirubin is most elevated in the blood in cases of hepatocellular jaundice?

Answer 91

**Both** unconjugated bilirubin and conjugated (bilirubin diglucuronide)

Question 92

Why do some newborns develop neonatal jaundice? Is this a problem?

Answer 92

Their hepatic bilirubin glucuronyltransferase (the conjugating enzyme) is not yet fully functional; yes, it can cause kernicterus (neonatal jaundice-induced encephalopathy)

Question 93

Why is unconjugated bilirubin called _indirect_ bilirubin? Why is conjugated bilirubin called _direct_ bilirubin?

Answer 93

It does not react as easily with reagent and is determined by 'total bilirubin - direct bilirubin;' it reacts easily with reagent and is directly measured

Question 94

\_\_\_\_\_\_\_\_\_\_ __________ is an energy carrier in the muscle formed by the phosphorylation of \_\_\_\_\_\_\_\_\_\_. Both of the above molecules can cyclize to form \_\_\_\_\_\_\_\_\_\_, which is quickly secreted by the kidneys.

Answer 94

Creatine phosphate, creatine; creatinine

Question 95

Decreased levels of plasma creatinine are indicative of: Elevated levels of plasma creatinine are indicative of: Elevated levels of creatine kinase are indicative of:

Answer 95

Muscle atrophy; kidney dysfunction; possible myocardial infarction

Question 96

What enzyme turns muscle creatine into creatine phosphate?

Answer 96

Creatine kinase

Question 97

Answer 97

A.

Question 98

Answer 98

A.

Question 99

Answer 99

D.

Question 100

Answer 100

A.

Question 101

Answer 101

E.

Question 102

Answer 102

E.

Question 103

Answer 103

A.

Question 104

Answer 104

A.

Question 105

Answer 105

B.

Question 106

Answer 106

D.