Unit 4 - Hgb Synthesis Flashcards
What is 90% of the dry weight of RBCs?
Hemoglobin
What is most of internal RBC metabolism geared toward?
Maintaining Hgb function
What promotes gas exchange in the capillaries in RBCs?
RBC membrane structure and deformability
What kind of protein is hemoglobin?
Conjugated protein
What is the molecular weight of hemoglobin
~67,000
How much of the RBC does hemoglobin occupy?
1/3 the mass of the RBC
Moieties means
portions
What is heme made up of?
Iron + porphyrin ring
How many heme per RBC?
4 per molecule
What is globin made up of?
Protein portion
How many chains of globin in an RBC?
4 chains
2 chains of one type
2 chains of another type (a2B2)
How much hgb synthesis at pronormoblast stage?
Minimal
How much hgb synthesis at normoblast stage?
Maximum
What stage of RBC is producing the least amount of hgb synthesis?
Pronormoblast
What stage of RBC is producing the most amount of hgb synthesis?
Normoblast
What happens to mRNA production after nucleus is extruded?
No new mRNA is produced
What does the remaining mRNA in a reticulocyte do?
Continues hgb synthesis
Hgb from retic synthesis is ___ of total hgb in rbc
20-25%
Biochemical pathways for synthesis include
Heme portion
Global portion
Assembly of molecule
Different forms of hemoglobin
Normal human hgb types
Variant human hgb due to genetics
Chemically modified hemoglobin variants
Heme is also known as
Ferroprotoporphyrin
What is the heme structure
Ring structure of 4 pyrrole rings attached together at methylene bridges
What is the ring structure of heme called
Protoporphyrin
What are the 4 rings that join in a heme?
Pyrrole
What is it that holds the 4 pyrrole rings together in a heme group?
Methylene bridges
What is at the center of the protoporphyrn?
Ferrous iron
What form of iron cannot bind oxygen?
Ferric iron
What is heme considered in biochemical terms
A prosthetic group attached to a protein
What are globin chains
Protein chains folded into complex tertiary structure with a pocket to hold heme
Normal globin
variants are named by what?
Greek letters
What kind of structure is hemoglobin?
A tetramer of protein chains, 2 of each type
What are the heme moiety
Iron
Glycine
Succinyl Co-A
What are the global moiety
Amino acids
When does hemoglobin synthesis occur
Pronormoblast stage through reticulocyte stage
Where in the cell is heme produced
Mitochondria
Cytoplasm