Heme Metabolism - w5

Question 1

What is the structure of porphyrins?

Answer 1

cyclic compounds that bind metal ions

Question 2

What is the structure of heme?

Answer 2

tetrapyrrole ring of protoporphyrin IX with central Fe2+

Question 3

What links the pyrrole rings of heme together?

Answer 3

methenyl bridges (-HC=)

Question 4

How many groups of compounds are there in a heme tetrapyrrole ring?

Answer 4

4 methyl groups
2 vinyl groups
2 propionate groups

Question 5

What are the two places where heme is synthesized?

Answer 5

85% in bone marrow erythroid precursors / 15% liver

Question 6

What is the enzyme that detoxifies oxidative stress in the body?

Answer 6

catalase

Question 7

What do cytochromes do?

Answer 7

detoxify

Question 8

What is the important AA and coenzyme that begins heme synthesis?

Answer 8

glycine and succinyl co-A

Question 9

Where does the finished product heme (with Fe2+) get assembled?

Answer 9

mitochondria

Question 10

What is the enzyme that has the highest catalytic power?

Answer 10

uroporphyrinogen decarboxylase

Question 11

What is clinical ion name for Fe2+?

Answer 11

ferrous ion

Question 12

What is the rare defect in heme synthesis?

Answer 12

porphyrias

Question 13

What causes porphyrias?

Answer 13

accumulation and increased excretion of porphyrins or porphyrin precursores (not accu of heme)

Question 14

How does porphyria affect the skin?

Answer 14

increases skin photosensitivity (oxidative damage)

Question 15

What is the most common porphyria (hepatic)?

Answer 15

porphyria cutanea tarda

Question 16

What are the physical symptoms of porphyria cutanea tarda?

Answer 16

skin eruptions and red coloured urine

Question 17

Which porphyria is congenital?

Answer 17

erythropoietic

Question 18

What degrades RBCs?

Answer 18

phagocytes in the liver and splkeen

Question 19

What enzyme begins heme degradation by releasing Fe2+?

Answer 19

heme oxygenase

Question 20

Which compound in heme degradation is green?

Answer 20

biliverdin

Question 21

How does bilirubin get transported to liver?

Answer 21

first binds to albumin to make a complex

Question 22

In liver, what does bilirubin conjugate with?

Answer 22

glucaronic acid

Question 23

Where does conjugated bilirubin go to?

Answer 23

bile

Question 24

Which stage of bilirubin becomes feces?

Answer 24

stercobilin

Question 25

What is the system that helps clear defective cells in our body?

Answer 25

reticulo-endothelial system

Question 26

What is another name for jaundice?

Answer 26

icterus

Question 27

Hemolytic anemia causes an accumulation of what type of bilirubin the blood?

Answer 27

unconjugated bilirubin

Question 28

Bile duct obstruction causes an increase of what type of bilirubin in the blood?

Answer 28

conjugated bilirubin