Biologi Kelas 12: Sistem Golongan Darah ABO

Summary

This video explains the ABO blood group system, detailing the inheritance of blood types based on alleles A, B, and O. It covers the concepts of dominant and recessive traits, and how genotypes like AA, AO, BB, BO, AB, and OO determine blood types A, B, AB, and O. The script further illustrates the genetic combinations, explaining how offspring can inherit blood types A, B, AB, or O based on their parents’ genotypes, with examples showing potential inheritance patterns and the significance of heterozygous and homozygous traits.

Takeaways

• 😀 The ABO blood group system is based on three main alleles: IA, IB, and IO.
• 😀 Alleles IA and IB are dominant, while allele IO is recessive.
• 😀 The four possible human blood types are A, B, AB, and O.
• 😀 Blood type A can have two genotypes: homozygous IAIA or heterozygous IAIO.
• 😀 Blood type B can also have two genotypes: homozygous IBIB or heterozygous IBIO.
• 😀 Blood type AB is the result of a heterozygous genotype IAIB.
• 😀 Blood type O must have a homozygous genotype IOIO to be expressed.
• 😀 A child inherits their blood type based on the alleles received from their parents.
• 😀 A parent with heterozygous blood type A (IAIO) can pass on either IA or IO to their child.
• 😀 It is possible for two parents with blood type A to have a child with blood type O if both parents carry the IO allele.
• 😀 The inheritance of blood type can lead to surprising results, such as a child with blood type O even if both parents have blood type A.

Q & A

What is the ABO blood group system based on?

The ABO blood group system is based on three alleles: IA, IB, and IO. IA and IB are dominant, while IO is recessive.

What is the significance of the IA and IB alleles in blood group inheritance?

The IA and IB alleles are dominant, which means that if an individual inherits either of these alleles, that blood group phenotype will be expressed.

What is the recessive allele in the ABO system, and what does it result in?

The recessive allele in the ABO system is IO. An individual needs two copies of this allele (IOIO) to have blood group O.

What are the possible genotypes for someone with blood group A?

A person with blood group A can have two possible genotypes: homozygous (IAIA) or heterozygous (IAIO).

How does blood group B differ in terms of genotypes?

People with blood group B can have two possible genotypes: homozygous (IBIB) or heterozygous (IBIO).

What genotype must a person with blood group AB have?

A person with blood group AB must have the genotype IAIB, meaning they inherit both the IA and IB alleles.

What is the genotype of someone with blood group O?

A person with blood group O must have the genotype IOIO, meaning they inherit the recessive IO allele from both parents.

How can a child have blood group O if both parents have blood group A?

If both parents have blood group A but are heterozygous (IAIO), they can each pass on the IO allele to their child, resulting in blood group O (IOIO).

What is the ratio of phenotypes when both parents with blood group A (heterozygous) have children?

When both parents with blood group A (heterozygous, IAIO) have children, the expected phenotype ratio is 3 blood group A to 1 blood group O.

Can a child with blood group O have parents who both have blood group A?

Yes, a child with blood group O can have parents both with blood group A, as long as both parents are heterozygous (IAIO) and pass on the IO allele.