L4- Hemoglobin structure synthesis and breakdown

Question 1

HEME synthesis function?

Answer 1

hemoglobin cytochromes and myoglobin

Question 2

location of heme synthesis?

Answer 2

involves both mitochondria and the cytosol

occurs in almost every cell but HB synthesis only in progenitors of RBCs.

Question 3

first step of Heme synthesis?

Answer 3

Glycine nad succinyl CoA condense together to form Aminolevulinic acid (ALA) by the action of enzyme Aminolevulinic acid synthesis and vitamin B6 as its cofactor

Question 4

second step of Heme synthesis?

Answer 4

2 molecules of ALA condense together to form porphobilinogen by the action of the enzyme Aminlevulinic dehydratase.

Question 5

2 important enzymes?

Answer 5

porphobilinogen deaminase and uroporphorinogen decarboxylase end up forming protoporphyrin IX

Question 6

protoporphyrin IX

Answer 6

it combines with ferrous to form heme by the action of enzyme ferrochelatase

Question 7

which enzyme is the rate limiting enzyme

Answer 7

its the ALA synthase its inhibited by heme and requires vitamin B6

Question 8

what’s special about ALA synthase in the liver.

Answer 8

it is inhibited by heme by=ut it causes the oxidation of iron into ferric state forming hemin.
hemin inhibits ALA synthase in 2 ways by allosteric modification and by repressing its transcription.

Question 9

in which condition is Porphobilinogen deaminase deficient in?

Answer 9

acute intermittent porphyria

Question 10

in which condition is Uroporphorinogen deficient in?

Answer 10

porphyria cutanea tarda

Question 11

What does lead cause in hemesynthesis?

Answer 11

it inhibits ALA dehydratase and Ferrochelatase

Question 12

which enzyme is inhibited by iron deficiency?

Answer 12

FERROCHELATASE

Question 13

which enzyme is affected by vitamin B6 deficiency?

Answer 13

ALA synthase

Question 14

What is porphyria?

Answer 14

these are inherited defects In heme synthesis resulting in a group of heterogeneous diseases of porphyrin metabolism, characterized by dermatological neurological and psychological manifestations

Question 15

symptoms due to accumulation of aminolevulinic acid?

Answer 15

Neurological symptoms

Question 16

Symptoms due to accumulation of protoporphyrins?

Answer 16

Causes photosensitivity, worsened by sunlight p450 inducing drug (stimulates the heme synthesis pathway to increase production) 9barbiturates and alcohol)

Question 17

Porphyria cutanea tarda?

Answer 17

deficiency in uroporphoblinogen decarboxylase its an autosomal dominant condition that has a late onset it causes photosensitivity blasting snsnssjaknskns hyper pigmentation and dark red brown urine

Question 17

Porphyria cutanea tarda?

Answer 17

deficiency in uroporphoblinogen decarboxylase its an autosomal dominant condition that has a late onset it causes photosensitivity blasting hyper pigmentation and dark red brown urine

Question 18

Porphyria cutanea tarda?

Answer 18

deficiency in uroporphoblinogen decarboxylase its an autosomal dominant condition that has a late onset it causes photosensitivity blasting snsnssjaknskns hyper pigmentation and dark red brown urine

Question 18

Porphyria cutanea tarda?

Answer 18

deficiency in uroporphoblinogen decarboxylase its an autosomal dominant condition that has a late onset it causes photosensitivity blasting snsnssjaknskns hyper pigmentation and dark red brown urine

Question 18

Porphyria cutanea tarda?

Answer 18

deficiency in uroporphoblinogen decarboxylase its an autosomal dominant condition that has a late onset it causes photosensitivity blasting snsnssjaknskns hyper pigmentation and dark red brown urine