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MCM Final > Heme Sythesis & Degradation > Flashcards

Heme Sythesis & Degradation Flashcards

1
Q

Hemoglobin gives RBCs the ability to transport ________ throughout the body

A

Oxygen

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2
Q

Hemoglobin is composed of ____ globular sub-units each bound to an ______ containing _______

A

4

Iron

Heme

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3
Q

Heme has a heterocyclic __________ ring with ______ present in the center

A

Porphyrin

Iron

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4
Q

Each porphyrin ring contains ____ 5-membered rings. Each ring contains ______ connected by single ____________.

A

Each porphyrin contains FOUR 5-membered rings. Each ring contains NITROGEN and is connected by single CARBON BRIDGES.

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5
Q

Iron is present in hemoglobin is __________ state

A

Ferrous

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6
Q

Heme is present in __________, __________, &. ___________.

A

Hemoglobin, myoglobin, and cytochromes

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7
Q

Heme synthesis occurs primarily in what parts of the body?

A

Liver

Erythropoietin cells of bone marrow

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8
Q

Where does each phase of the biosynthesis of heme take place?

A

Phase I : mitochondria

Phase II : cytoplasm

Phase III: mitochondria

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9
Q

What are the starting ingredients of heme synthesis?

What inhibits the first step of the process?

A

Succinyl CoA and Glycine

Heme inhibits

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10
Q

In the synthesis of heme, what crossed the cytoplasmic barrier (from mitochondria to cytoplasm)?

A

ALA

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11
Q

In the synthesis of heme, what crosses the mitochondrial barrier (from cytoplasm to mitochondria)?

A

Copro-porphyrin open III

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12
Q

A defect in one or more stages of heme synthesis will lead to________

A

Porphyria

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13
Q 
Which porphyria is autosomal recessive?
A) Variegated porphyria
B) Acute intermittent porphyria
C) Congenital erythropoietic porphyria
D) Porphyria cutanea tarda
A

C) Congenital erythropoietic porphyria

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14
Q

ALA Synthase is used in the first step of heme synthesis. In order to function, it needs ________ which has a cofactor of __________.

A

PLP (pyridoxal phosphate)

Vitamin B6

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15
Q

A deficiency in ALA-synthase or Vitamin B6 will cause ______

A

Anemia

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16
Q

In the first step of heme synthesis, Succinyl CoA is __________ producing a byproduct of CO2.

A

Decaroxylated

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17
Q

TRUE or FALSE: Porphyrias are INHERITED metabolic disorders.

A

TRUE

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18
Q

When you see neurological symptoms in a porphyria patient, you would expect what type of disease?

A

Acute hepatic

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19
Q

When you see skin issues and photosensitivity in a porphyria patient, you would expect what type of disorder?

A

Erythropoietic

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20
Q

Acute intermittent porphyria

Deficient enzyme: ?

Type of porphyria: ?

Autosomal recessive or dominant?

What is produced in excess?

Symptoms: ?

A

Porphobilinogen deaminase

Hepatic

Dominant

ALA and PBG

Neurological disfunction and abdominal pain

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21
Q

Congenital erythropoietic porphyria

Deficient enzyme: ?

Type of porphyria: ?

Autosomal recessive or dominant?

What is produced in excess?

Symptoms: ?

A

Uroporphyrinogen III (co)synthase

Erythropoietic

Recessive

Uroporphyrinogen I and its red-colored, air oxidation product uroporphyrin

Photosensitivity, red color in urine and teeth; hemolytic anemia

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22
Q

Porphyria Cutanea Tarda

Deficient enzyme: ?

Type of porphyria: ?

Autosomal recessive or dominant?

What is produced in excess?

Symptoms: ?

A

Uroporphyrinogen Decarboxylase

Hepatoerythropoietic

Dominant

Uroporphyrinogen III which converts to uroporphyrinogen I

Photosensitivity resulting in vesicles and bullpen on skin, red-wine colored urine

*Most common porphyria in the United States

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23
Q

Variegate porphyria

Deficient enzyme: ?

Type of porphyria: ?

Autosomal recessive or dominant?

Symptoms: ?

A

Protoporphyrinogen IX Oxidase

Hepatic

Dominant

Photosensitivity & Neurologic symtoms and developmental delay in children

*King George III

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24
Q

RBC undergo breakdown every ____ days and this is handled by the ______-endothelial system, which degrades ________
Globin is broken down into ______ and ______ which is removed for degradation.

A

120

Reticulo -endothelial

Hemoglobin

Amino acids & heme

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25
Q

Heme is what color in the body?

What enzyme converts heme to biliverdin?

A

Heme = purple

Heme oxygenase

26
Q

What color is biliverden?

What enzyme converts biliverdin to bilirubin?

A

Biliverdin = green

Bilirubin reductase

27
Q

What color is bilirubin in the body?

What does bilirubin associate with in the bloodstream?

A

Bilirubin = Red-orange

Albumin

28
Q

In the liver, bilirubin requires what to go from “indirect” to “direct” - Bilirubin-monoglucuronide?

A

UDP-glucoronyl transferase

*rate-limiting rxn

29
Q

In the liver, Bilirubin-monoglucuronide “indirect” requires what to go to Bilirubin-diglucuronide “direct”?

A

UDP-glucoronyltransferase

(Yes it’s the same enzyme as the previous reaction)

*rate-limiting rxn

30
Q

In the small intestine, bilirubin-diglucoronide goes to ________ which goes to _________.

A

Bilirubin

Urobilinogen

31
Q

Urobilinogen can either stay in the ________ and go to ________ with the help of microbial enzymes to be excreted as ________ OR it can go to the ______ where it will be converted to __________ to be excreted as _________.

A

Small intestine
Stercobilin
Feces

Kidney
Urobilin
Urine

32
Q

Which of the following is yellow and which is colorless?

Urobilinogen

Urobilin

A

Urobilinogen = colorless

Urobilin = yellow

33
Q

Crigler-Najjar Syndrome and Gilbert syndrome are associated with a deficiency in what enzyme?

A

Glucuronyl transferase
<10% residual activity (CN)
25% residual activity (G)

34
Q

The oxidation of heme liberates one of the ____________as ________,converts the________iron into ________iron and produces the green pigment __________.

A 
Carbon bridges 
CO (carbon monoxide) 
Ferrous (Fe2+)
Ferric (Fe3+)
Biliverdin
35
Q

Reduction of biliverdin produces the red-orange bilirubin that is conjugated in the _________, collected in _______ and secreted into the _____________,where it undergoes _____________ to urobilinogen

A

Liver
Bile
Small intestine
Microbial reduction

36
Q

T or F: The iron in the porphyrin ring of heme is in the ferrous form.

A

True, the iron in heme is 2+ which is the ferrous form

The ferric form of iron is Fe3+

37
Q

In heme degradation, the enzyme ___________ removes the bridge between pyrole rings of heme, releasing ________. Iron is oxidized from __________ to __________.

The enzyme used above is induced 100x by ______, _________ and __________.

A

Heme oxygenase
CO
Ferrous to ferric

Heme, metal ions, phenylhydrazine (a drug)

38
Q

The enzyme responsible for degrading heme to biliverdin is _________. The enzyme used to take biliverdin to bilirubin is __________ and _______ is also needed.

A

Heme oxygenase

Biliverdin reductase
NADPH

39
Q

Bilirubin is released into the bloodstream but because free/unconjugated/indirect bilirubin is _________, it is bound to _________.

A

Insoluble

Albumin

40
Q

A protein carrier is needed for _________ uptake of bilirubin.

Bilirubin is conjugated with _________ to make it ________. This form is called _______ bilirubin.

A

Hepatic

Glucoronic acid
Soluble

Direct

41
Q

What is the rate limiting step in the removal of bilirubin from blood?

If babies do not have sufficient amounts of this enzyme, they will get?

A

UDP glucoronyl transferase

Jaundice

42
Q

Pre-hepatic jaundice indicates ________ production of ______________ bilirubin

A

An increased

Unconjugated

43
Q

Excess hemolysis, internal hemorrhage, neonatal jaundice due to problems with incompatibility of maternal-fetal blood groups is associated with pre, intra or post hepatic jaundice?

A

Pre-hepatic jaundice

44
Q

*With pre-hepatic jaundice, you would expect to see ______ blood levels of _______ or ________ bilirubin,
Normal levels of _______ BR

________ levels of ALT and AST.

And ______ would be present in urine but not ________.

A

Elevated

Unconjugated or indirect

Direct

Normal

Urobilinogen
Direct BR

45
Q

Intra-hepatic jaundice is characterized by ___________ hepatic uptake, conjugation or secretions of conjugated BR.

Examples include?

A

Impaired (hepatic uptake)

Liver cirrhosis
Viral hepatitis
Criggler-Najjar syndrome
Gilbert syndrome

*Often due to drug abuse

46
Q

With intra-hepatic jaundice, you would expect to see ______ in _________ and _________ bilirubin.

__________ in ALT and AST

__________ levels of urobilinogen in urine

And __________ detected in urine as well

A

Variable increases
Unconjugated and conjugated

Increases

Normal

Conjugated BR

47
Q

Post-hepatic jaundice involves problems with ___________ and is also called ________ which means decrease _______ flow

A

Bilirubin excretion

Cholestasis

Bile

48
Q

Post-hepatic involves obstruction to _______ drainage in _______ or _______ and can present as…..

A

Biliary

Liver or bile ducts

Gall stones, cholangiocarcinoma, infiltrative liver disease, lesions (tumor, abscess or granulomatous disease)

49
Q

With post-hepatic, you would expect to see ________ blood levels of conjugated BR

_____ levels of ALT and AST

_______ ALP and bile salts

________ is present in urine, making it _______

And there is no _______ in feces so they are ______

A

Elevated

Normal

Elevated

Conjugated BR
Dark

Stercobolin
Pale

50
Q

Autoimmune, abnormal hemoglobin are clinical examples of _________ jaundice

A

Prehepatic

51
Q

Hepatitis A, B, C, acetaminophen or alcohol induced, Gilbert’s syndrome, Crigler-Najjar syndrome, DUbin-Johnson Syndrome, Rotor’s syndrome, Wilson’s disease, neonatal are all clinical examples of __________ jaundice

A

Intrahepatic

52
Q

Drug use, primary biliary cirrhosis, cholangitis, gall stones, pancreatic tumor, cholangiocarcinoma are all clinical examples of __________ jaundice

A

Post-hepatic

53
Q

Gilbert’s syndrome, Crigler-Najjar syndrome, Dublin-Johnson syndrome, Rotor’s Syndrome are all clinical examples of intrahepatic jaundice due to ___________in bilirubin __________

A

genetic errors

Metabolism

54
Q

Neonatal jaundice is also called _________ jaundice and is due to elevated __________ bilirubin.

Major contributing factors include:

  • the breakdown of _______ as it is replaced with adult hemoglobin
  • immature _______ metabolic pathways, unable to ________ and ______bilirubin
  • deficiency of _______ enzyme
A

Physiological

Unconjugated

Fetal hemoglobin

Hepatic

Conjugate & excrete

UDP-GT

55
Q

___________ is a common treatment for neonatal jaundice. The exposure to ________ turns bilirubin into a ________ form, which makes it easier to excrete.

A

Phototherapy

Light

Soluble

56
Q

In ___________ syndrome type I, patients are born without _________ , in type II, patients are born with a mutated form of _______ resulting in _____ activity.

A

Criggler-Najjar

UDP-GT

UDP-GT

10%

57
Q

*Criggler-Najjar Syndrome causes BR to ___________ in the _________ of ________,which causes___________and _________.

Therapy includes: ??

A

Accumulate in the brain of babies

Encephalopathy & brain damage

Blood transfusions, phototherapy, heme oxygenase inhibitors, oral calcium phosphate and carbonate,liver transplantation (before brain damage occurs and before phototherapy becomes ineffective)

58
Q

Gilbert Syndrome results in __________ activity of __________ (enzyme) ___%

Serum BR may increase with _____, ______or ______

Gilbert syndrome affects ____ of the population

A

Reduced UDP-GT

25%

Fasting, stress or alcohol consumption

2-10%, relatively common

59
Q

Hepatitis means ________ of the _________

Causes include viral infections such as ______, ______& ______, as well as _________ and __________

We see ______ levels of unconjugated and conjugated bilirubin in blood

Causes a _____ discoloration in the _____ and _______.

Urine is _______

A

Inflammation

Liver

Hep A, B & C
Alcoholic cirrhosis
Liver cancer

Elevated

Yellow
Skin and sclera of the eyes

Tea-colored (urine)

60
Q

Bruises change colors based on the breakdown of ________ from …

Heme which is ______
To ________ which is _______
To ________ which is _______
To _________ which is _______

A

Hemoglobin

Red/purple

Biliverdin=green

Bilirubin = orange/red

Hemosiderin = brown

MCM Final (7 decks)

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