What factors regulate globin biosynthesis?
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Heme, iron, and other iron-related transcription factors.
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What factors regulate globin biosynthesis?
Heme, iron, and other iron-related transcription factors.
Where is the ferrous Fe2+ located in the heme?
In the center of the heme.
What is the composition of the HbA1 (adult hemoglobin) tetramer?
2 α-globin and 2 β-globin (α2β2).
What are the three stages of hemoglobin synthesis?
How does globin synthesis begin?
Globin synthesis begins with transcription of the globin gene into mRNA and then the translation into protein.
What is heme composed of?
Protoporphyrin IX and ferrous Fe2+.
What are the two forms of hemoglobin (Hb) based on oxygenation?
Oxyhaemoglobin and Deoxyhaemoglobin.
What are the four allosteric factors affecting heme's oxygen binding affinity?
What are the two Alpha-like genes?
Alpha and Zeta.
What is the globin protein superfamily characterized by?
Heme-containing globular proteins.
Where is hemoglobin synthesized?
Inside the immature erythrocytes (RBCs).
What happens when hemoglobin binds to oxygen in the lungs?
The binding of the first O2 molecule to deoxy Hb shifts the iron toward the plane of the heme ring, triggering conformational changes in the apoprotein (globin).
What are the components of the heme part of hemoglobin?
Tetrapyrol and Fe2+.
What happens when heme concentration is high?
Heme binds to an inhibitor molecule, blocking the ALA enzyme.
What are the characteristics of the T-form of hemoglobin?
How many alpha-like genes are in the globin gene cluster?
2 alpha-like genes.
What does the heme group consist of?
The heme group consists of Fe2+ ion held in a porphyrin ring.
What is the composition of HbF?
HbF consists of (α2γ2) and is found normally in fetuses and newborns.
How do the 4 globin chains bind to oxygen molecules?
In a cooperative manner.
How does iron affect ALA synthase?
Iron acts as an activator for ALA synthase.
What is the T-form of hemoglobin?
The T-form (Taut) is the deoxy form of Hb found in tissue, characterized by low oxygen affinity and constrained movement.
What other molecules does hemoglobin transport besides oxygen?
Hemoglobin also carries CO2 and protons (H+) from tissues to the lungs.
List the Beta-like genes in the order they are expressed during development.
What is porphyrin?
Porphyrin is an organic compound consisting of 4 pyrrole molecules (Tetrapyrol) called Protoporphyrin.
Which enzyme in heme synthesis is regulated by iron?
ALA synthase.
In what ways do the seven distinct polypeptide chains (Globins) differ?
Where is the human β-globin locus located?
On chromosome 11.
What are the primary functions of hemoglobin?
How is the regulation of gene expression mediated?
By regulatory elements or protein factors (DNA-binding proteins) that interact or bind to specific DNA regions (domains) like the promoters, enhancers, or silencers.
What are the components of the globin part of hemoglobin?
2 α and 2 β protein chains.
What hemoglobin types are produced by the Beta Globin Gene Cluster?
Hb F, Hb A2, Hb A.
What is the role of heme in globin protein synthesis?
Heme activates globin protein synthesis and the formation of hemoglobin.
How does HbF's oxygen binding affinity compare to HbA?
HbF is able to bind oxygen with greater affinity than HbA.
What are the specific DNA regions involved in gene regulation?
Promoters, enhancers, or silencers.
How many additional bonds does Fe2+ form, and with what?
2 additional bonds: 1 bond with the Histidine (amino acid residue of globin) and 1 bond with the Oxygen.
How many beta-like genes are in the globin gene cluster?
5 beta-like genes.
What type of protein is hemoglobin?
A tetrameric protein consisting of 4 globin subunits.
What is the prosthetic group in hemoglobin?
Heme.
What does hemoglobin transport after releasing O2 at the tissues?
Hemoglobin transports CO2 and protons to the lungs.
On which chromosome is the Alpha Globin Gene Cluster located?
Chromosome 16.
What is the total number of bonds formed by Fe2+ in the heme?
6 bonds (4 with nitrogen atoms of the porphyrin ring and 2 additional bonds).
How many O2 molecules can hemoglobin bind to?
Hemoglobin binds to 4 O2 molecules.
What are the five Beta-like genes?
Beta, Delta, 2 Gamma, and Epsilon.
What is another name for Tetrapyrol?
Protoporphyrin IX.
How many distinct polypeptide chains (Globins) are found in humans?
Seven distinct polypeptide chains.
What is the R-form of hemoglobin?
The R-form (Relaxed) is the oxygenated form of Hb found in the lungs, characterized by high oxygen affinity and freedom of movement for the dimers.
What type of protein is hemoglobin classified as?
A conjugated protein or metalloprotein containing Fe2+.
How is the control of globin production achieved?
The control is either by quantitatively increasing or decreasing mRNA transcription or protein synthesis.
How many nitrogen atoms of the porphyrin ring does Fe2+ bind to?
4 nitrogen atoms.
Where is the Alpha globin gene located?
On the short arm of chromosome 16.
What is the composition of HbA2?
HbA2 consists of (α2δ2) and is found in small amounts in adults.
What happens when protoporphyrin combines with a metal iron?
It forms Metalloporphyrin.
What are the DNA-binding proteins or elements called?
Effector molecules.
Which genes are part of the Alpha Globin Gene Cluster?
Zeta 2, Zeta 1, Alpha 2, Alpha 1.
How many genes are in the globin gene cluster?
7 genes.
At what level is globin production mainly controlled?
Globin production is mainly controlled at the transcription level.
What are the two types of effector molecules?
What are the characteristics of the R-form of hemoglobin?
