SISTEMA ABO - Grupos Sanguíneos - Resumo | Biologia com Samuel Cunha

Summary

In this educational video, the instructor explains the genetics of the ABO blood type system, covering the four blood types (A, B, AB, O) and the underlying genetic principles. The instructor introduces concepts like polyallelic inheritance, codominance, phenotype, and genotype. He highlights how blood types are determined by the presence of specific glycoproteins (agglutinogens) in red blood cells, as well as antibodies in the plasma. The video also explores how blood types influence donation compatibility and provides examples through genetic crosses. The instructor invites viewers to practice and learn more about the RH factor in a follow-up lesson.

Takeaways

• 😀 Blood types are determined by three alleles: IA, IB, and i.
• 😀 Polyallelism occurs when more than two alleles determine a characteristic, as seen in the ABO blood group system.
• 😀 Codominance happens when both IA and IB alleles are expressed simultaneously in blood type AB.
• 😀 The phenotype refers to the observable traits (blood type), while the genotype refers to the genetic makeup (the specific alleles inherited from both parents).
• 😀 People with blood type A have agglutinogen A in their red blood cells and produce anti-B antibodies.
• 😀 People with blood type B have agglutinogen B in their red blood cells and produce anti-A antibodies.
• 😀 Blood type AB individuals have both agglutinogen A and B in their red blood cells and do not produce anti-A or anti-B antibodies, making them universal recipients.
• 😀 Blood type O individuals do not have agglutinogen A or B and can only receive blood from other type O individuals, but can donate to anyone, making them universal donors.
• 😀 Genetic inheritance can result in various blood types in children, with blood type AB being a potential outcome from parents with different genotypes.
• 😀 The Rh factor (positive or negative) is another factor that determines blood compatibility, and it will be discussed in more detail in future lessons.

Q & A

What are the four main blood types in the ABO system?

The four main blood types in the ABO system are A, B, AB, and O.

What does 'polyallelia' mean in genetics?

Polyallelia refers to the situation in genetics when more than two alleles are available to determine a characteristic, such as blood type.

What is 'codominance' in the context of blood types?

Codominance occurs when two alleles, such as IA and IB, are both expressed equally without one cancelling the other out, as seen in individuals with blood type AB.

What is the difference between 'phenotype' and 'genotype' in genetics?

Phenotype refers to the observable trait, such as blood type, while genotype refers to the genetic makeup, or the alleles present in the individual's genes.

Why does a person with blood type A produce anti-B antibodies?

A person with blood type A has A antigens in their red blood cells but lacks B antigens. To protect against foreign blood types, they produce anti-B antibodies.

Can a person with blood type O donate blood to anyone?

Yes, a person with blood type O is considered the universal donor because their blood does not contain A or B antigens, making it compatible with all blood types.

What happens if a person with blood type B receives blood from someone with blood type A?

If a person with blood type B receives blood from a type A donor, their immune system will produce anti-A antibodies to attack the foreign blood, causing a harmful reaction.

What blood types can a person with blood type AB receive?

A person with blood type AB can receive blood from any blood type (A, B, AB, or O) because they have both A and B antigens and do not produce anti-A or anti-B antibodies.

What is the genotype of someone with blood type O?

The genotype of a person with blood type O is homozygous recessive, meaning their alleles are 'ii,' indicating an absence of both A and B antigens.

How does blood type inheritance work between a parent with blood type A and a parent with blood type B?

When one parent has blood type A (IAi or IAIA) and the other has blood type B (IBi or IBIB), their children can inherit any of the following blood types: A, B, AB, or O, depending on the alleles inherited from each parent.