Heme Metabolism

Question 1

Heme is produced majorly in the ……….

Answer 1

Bone marrow
Liver

Question 2

The heme synthesis is an how many step process

Answer 2

8 step process

Question 3

Iron exist in hemoglobin in the ……… state

Answer 3

Ferrous ( reduced)

Question 4

The types of heme are

Answer 4

Heme A in cytochrome A
Heme B in myoglobin ,hemoglobin and cyclooxygenase
Heme C in cytochrome C links via cysteine
Heme O.in bacterial oxidase

Question 5

The most abundantly Heme is

Answer 5

Heme B

Question 6

Where does tge last three steps of heme synthesis occur

Answer 6

Mitochondria

Question 7

Where does tge last three steps of heme synthesis occur

Answer 7

Mitochondria

Question 8

Heme synthesis is largely dependent on the availability of which iron

Answer 8

Fe2+

Question 9

Deficiency of ALAS 2 in the synthesis of heme results in ……….

Answer 9

X-linked sideroblastic anaemia

Question 10

The enzyme Aminolevulinic acid dehydratase is sensitive to ……….

Answer 10

pH and Mg 2+

Question 11

Aminolevulinic acid is inhibited by heavy metals e.g

Answer 11

Lead

Question 12

Deficiency of Aminolevulinic acid dehydratase leads to …………

Answer 12

Aminolevulinic acidic dehydratase deficiency porphyria

Question 13

The linear tetra pyrrole formed during heme synthesis is ………

Answer 13

Hydroxymethylbilane

Question 14

Enzyme involved in the synthesis of HMB is ………….

Answer 14

HMB synthase
PBG deaminase

Question 15

Deficiency of PBG deaminase leads to

Answer 15

Intermittent porphyria

Question 16

HMB is linked by ………… ring

Answer 16

Amine

Question 17

HMB is converted to …….. by UROS

Answer 17

UPGIII synthase

Question 18

The deficiency of UROS leads to…….

Answer 18

Congenital erythropoietic porphyria ( Autosomal recessive)

Question 19

UPG III is converted to CPG III by what process

Answer 19

Decarboxylation of UPG III to CPG III
Acetate to methyl
And release of 4CO2 molecules

Question 20

UROD deficiency leads to ……. porphyria

Answer 20

Familial porphyria cutanea tarda and
Hepatoerythropoietic porphyria

Question 21

The enzyme responsible for conversion of CPG III to phorphobilinogen IX is

Answer 21

CPG III Oxidase

Question 22

In the conversion of CPG III to Protoporphyrin IX what changes occur to the side chain

Answer 22

Decarboxylation of propionyl to vinyl

Question 23

Reduced amount of CPG III oxidase leads to

Answer 23

Hereditary coproporphyria

Question 24

PPGIX is converted to PPIX by ………. processs

Answer 24

Oxidation

Question 25

PPGIX is converted to PPIX by ………. processs

Answer 25

Oxidation

Question 26

In the conversion of PPG IX to PPIX the bridges are converted from …………. to ………….

Answer 26

Methylene to methenyl

Question 27

Mutation in PPGoxidase causes…….

Answer 27

Variegate porphyria

Question 28

Another name for ferrochelatase

Answer 28

Heme synthase

Question 29

The major that regulate heme synthesis include

Answer 29

Expression of ALAS gene (ALAS 2)- major
Iron availability (decreased iron decrease ALAS 2 translation)
Globin

Question 30

Porphyria are classified based on

Answer 30

Bone marrow( hemoglobin synthesis)
Liver( cytochrome synthesis)

Erythropoietic mainly affects the skin
Hepatic : mainly affects the nervous system