Porphyrins and Hemoglobin

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Total cards: 24•Content version: v4•Public deck•Updated: 8/1/2026

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Front (Question)

Hemoglobin and myoglobin are chemically similar molecules that contain what chemical groups?

Back (Answer)

Porphyrin groups

Front (Question)

Porphyrin structure

Back (Answer)

Cyclic structure made of 4 pyrrole rings joined by methine bridges

Front (Question)

What produces heme?

Back (Answer)

Chelation of ferrous iron to protoporphyrin

Front (Question)

Heme

Back (Answer)

Prosthetic group of Hgb responsible for binding O2

Front (Question)

Porphyrias

Back (Answer)

Group of rare disorders that result from disturbances in heme synthesis

Front (Question)

Hemoglobinopathies caused by

Back (Answer)

• Qualitative defects in Hgb (aa mutations) • Structural defects

Front (Question)

Thalassemias are caused by

Back (Answer)

• Quantitative defects in Hgb production (less Hgb made) • Rate and quantity made affected

Front (Question)

Myoglobin

Back (Answer)

Simple heme protein found in cardiac and skeletal muscles

Front (Question)

Porphyrins

Back (Answer)

Chem intermediates in Hgb synthesis, Mgb, and other respiratory pigments called cytochromes

#10

Front (Question)

What indicates metabolic block of heme synthesis?

Back (Answer)

Excessive amounts of porphyrin intermediates in blood, urine, or feces

#11

Front (Question)

Porphyrinogens

Back (Answer)

• Reduced compounds that are intermediates in heme synthesis • Non-protein, iron-containing prosthetic group of Hgb

#12

Front (Question)

How are porphyrinogens converted to porphyrins?

Back (Answer)

Oxidation upon air exposure

#13

Front (Question)

Which of the 4 porphyrin isomers generates heme?

Back (Answer)

Type III isomer

#14

Front (Question)

Which of the 4 porphyrin isomers occur naturally?

Back (Answer)

Types I and III

#15

Front (Question)

Porphyrin photoactive properties (color, absorbance wavelength)

Back (Answer)

• Dark red color • 400 nm

#16

Front (Question)

Aqueous solubility of porphyrins varies with number of what functional group?

Back (Answer)

Carboxylic acid

#17

Front (Question)

Number of carboxylic acid functional groups in: Uroporphyrin Coproporphyrin Porphyrin

Back (Answer)

Uroporphyrin = 8 Coproporphyrin = 4 Porphyrin = 2

#18

Front (Question)

Which cells of the human body contain hemoproteins that can synthesize heme?

Back (Answer)

All cells

#19

Front (Question)

Primary organ sites of heme synthesis

Back (Answer)

Bone marrow and liver

#20

Front (Question)

___ molecule(s) of heme is produced from ____ molecules of ____

Back (Answer)

• One • 8 • delta-aminolevulinic acid (ALA)

#21

Front (Question)

The first and last steps of heme synthesize occurs where? Requires what?

Back (Answer)

• Mitochondria • Requires lots of energy

#22

Front (Question)

What is the last step of heme synthesis

Back (Answer)

Protoporphyrin converts to heme through action of ferrochelatase adding ferrous iron

#23

Front (Question)

Heme formation regulated by which mechanism? How?

Back (Answer)

Negative feedback whereby less heme stimulates more ALAS production

#24

Front (Question)

Rate-limiting enzyme of heme synthesis

Back (Answer)

ALAS