The primary difference between fraternal (dizygotic) and identical (monozygotic) twins lies in the way they originate:
1. **Fraternal Twins:**
- **Origin:** Fraternal twins result from the fertilization of two separate eggs by two different sperm cells during the same menstrual cycle.
- **Genetic Similarity:** Fraternal twins, like any siblings, share approximately 50% of their genetic material, which is the same as any other non-twin siblings born at different times.
- **Placenta and Amniotic Sac:** Fraternal twins typically have separate placentas and amniotic sacs, although there can be cases where they share a placenta but have separate amniotic sacs.
2. **Identical Twins:**
- **Origin:** Identical twins originate from the fertilization of a single egg by a single sperm, which then splits into two embryos. This can happen either shortly after fertilization or during the early stages of development.
- **Genetic Similarity:** Identical twins are genetically identical because they come from the same fertilized egg. They share 100% of their genetic material.
- **Placenta and Amniotic Sac:** Identical twins can share the same placenta and amniotic sac, especially if the split occurs after the formation of these structures. However, in some cases, they may have separate amniotic sacs.
In summary, the key distinction is that fraternal twins develop from two separate eggs fertilized by two different sperm, resulting in siblings with a genetic resemblance of about 50%. Identical twins, on the other hand, originate from a single fertilized egg that splits into two embryos, leading to individuals who are genetically identical.
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fraternal twins are formed from two different egg while identical are formed from one same egg
Answer:
The primary difference between fraternal (dizygotic) and identical (monozygotic) twins lies in the way they originate:
1. **Fraternal Twins:**
- **Origin:** Fraternal twins result from the fertilization of two separate eggs by two different sperm cells during the same menstrual cycle.
- **Genetic Similarity:** Fraternal twins, like any siblings, share approximately 50% of their genetic material, which is the same as any other non-twin siblings born at different times.
- **Placenta and Amniotic Sac:** Fraternal twins typically have separate placentas and amniotic sacs, although there can be cases where they share a placenta but have separate amniotic sacs.
2. **Identical Twins:**
- **Origin:** Identical twins originate from the fertilization of a single egg by a single sperm, which then splits into two embryos. This can happen either shortly after fertilization or during the early stages of development.
- **Genetic Similarity:** Identical twins are genetically identical because they come from the same fertilized egg. They share 100% of their genetic material.
- **Placenta and Amniotic Sac:** Identical twins can share the same placenta and amniotic sac, especially if the split occurs after the formation of these structures. However, in some cases, they may have separate amniotic sacs.
In summary, the key distinction is that fraternal twins develop from two separate eggs fertilized by two different sperm, resulting in siblings with a genetic resemblance of about 50%. Identical twins, on the other hand, originate from a single fertilized egg that splits into two embryos, leading to individuals who are genetically identical.