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Questions and Answers
Which globin genes are active during fetal growth and produce hemoglobin F?
Which globin genes are active during fetal growth and produce hemoglobin F?
Which globin genes take over after birth?
Which globin genes take over after birth?
Which type of hemoglobin is primarily the product of yolk sac erythroblasts and detectable only during the very earliest stages of embryogenesis?
Which type of hemoglobin is primarily the product of yolk sac erythroblasts and detectable only during the very earliest stages of embryogenesis?
By approximately what week of gestation are embryonic Hbs completely replaced by fetal Hb?
By approximately what week of gestation are embryonic Hbs completely replaced by fetal Hb?
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What are the globin chains present in hemoglobin F?
What are the globin chains present in hemoglobin F?
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Study Notes
Overview of Globin Genes and Hemoglobin Production
- The alpha globin locus is located on chromosome 16 and consists of four genes that contribute to the synthesis of the alpha globin protein.
- The beta globin locus is shown in the upper panel and includes two gamma globin genes that are active during fetal growth and produce hemoglobin F (HbF).
- Hemoglobin F is composed of two alpha globin chains and two gamma globin chains (alpha2gamma2) and is primarily present during fetal development.
- The production of embryonic hemoglobins (Hbs) is mainly attributed to yolk sac erythroblasts during the early stages of embryogenesis.
- Embryonic Hbs, such as Gower I, Portland, and Gower II, consist of embryonic globin chains including zeta and epsilon.
- Fetal Hb (HbF) replaces embryonic Hbs around the 14th week of gestation and is the predominant form of hemoglobin during this period.
- HbF has a higher affinity for oxygen compared to adult hemoglobin.
- After birth, the "adult" gene, beta, takes over and produces the majority of hemoglobin.
- The production of different types of hemoglobins occurs at specific stages of embryonic, fetal, and postnatal life.
- Severe alpha thalassemia may result in trace amounts of embryonic Hbs being present beyond the early stages of embryogenesis.
- The lower panel of the image represents the alpha globin locus, while the upper panel represents the beta globin locus.
- Understanding the regulation and expression of globin genes is crucial for comprehending normal and abnormal hemoglobin production.
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Description
Test your knowledge of the alpha and beta globin genes and their role in hemoglobin synthesis. Identify the genes involved in fetal and adult hemoglobin production.
