Non-Mendelian Inheritance I FULL VIDEO

Summary

This video explores Non-Mendelian inheritance, delving into genetic patterns beyond simple dominant-recessive rules. Topics include incomplete dominance, where traits blend; co-dominance, where both alleles are equally expressed; and multiple alleles, which create genetic diversity like the human blood type system. It also covers sex-linked genes, with examples like color blindness, as well as Y-linked traits like hypertrichosis. The video further examines sex-limited and sex-influenced traits, such as lactation in cattle and baldness in humans, highlighting the impact of hormones. The presentation demonstrates the complexity and variety of genetic inheritance beyond Mendelian laws.

Takeaways

• 😀 Incomplete dominance results in a phenotype that is a blend of the parents' traits, such as a pink flower from a red and white flower cross.
• 😀 Co-dominance occurs when two alleles are equally expressed, as seen in red and white cattle producing spotted offspring.
• 😀 Multiple alleles in a population increase genetic variation, such as the ABO blood group system in humans.
• 😀 Blood type in humans is determined by three alleles: A, B, and O, with type O being the universal donor and AB being the universal recipient.
• 😀 Sex-linked genes are found on the X or Y chromosomes, like color blindness, which is more common in males due to their single X chromosome.
• 😀 Hypertichosis pineal orus is a Y-linked trait affecting males, leading to excessive hair growth on the outer ear.
• 😀 Sex-limited traits are only expressed in one sex despite both sexes carrying the genes, like lactation in female cattle.
• 😀 Sex-influenced traits are more commonly expressed in one sex due to hormonal differences, such as baldness being more common in males.
• 😀 Males inherit Y-linked traits, such as hypertichosis, from their fathers, while females cannot be affected or carry Y-linked traits.
• 😀 Genetic inheritance patterns are complex and extend beyond Mendelian rules, including incomplete dominance, co-dominance, multiple alleles, sex-linked traits, and hormonal influences.

Q & A

What is incomplete dominance in genetics?

Incomplete dominance is a pattern of inheritance where the phenotype of the offspring is a blend between the two parental traits. For example, when a red flower is crossed with a white flower, the result is a pink flower.

Can you explain co-dominance and provide an example?

Co-dominance occurs when both alleles in a heterozygote are equally expressed in the phenotype. An example is when a white cow is crossed with a red cow, resulting in a red and white spotted cow, showing both parental traits equally.

What does multiple alleles mean in genetic inheritance?

Multiple alleles refer to the presence of more than two alleles for a particular gene in a population. For instance, human blood types (A, B, O) are determined by multiple alleles, which combine in different ways to produce the four blood types.

How does the blood type system work based on multiple alleles?

The human blood type system is determined by three alleles: A, B, and O. The A and B alleles are dominant, while O is recessive. A person’s blood type is determined by the combination of these alleles, such as AA or AO for type A, BB or BO for type B, AB for type AB, and OO for type O.

What is the role of antibodies in blood type compatibility?

Antibodies are proteins produced by the immune system that recognize and attack foreign antigens. For example, people with type A blood have anti-B antibodies, while those with type B blood have anti-A antibodies. Type O individuals have both anti-A and anti-B antibodies.

What are sex-linked genes, and how do they differ in males and females?

Sex-linked genes are genes found on the X or Y chromosomes. In humans, females have two X chromosomes, while males have one X and one Y. X-linked genes, such as the one for color blindness, are more commonly expressed in males because they only have one X chromosome.

Why is color blindness more common in males than females?

Color blindness is an X-linked recessive trait. Males, having only one X chromosome, will express the trait if that X carries the color blindness allele. Females, on the other hand, need two copies of the allele to express the condition, making it less common in females.

What is hypertichosis pine auris, and how is it inherited?

Hypertichosis pine auris is a Y-linked trait causing excessive hair growth on the outer ear. Since it is carried on the Y chromosome, only males, who have a Y chromosome, can inherit and express the trait. It is passed from father to son.

What are sex-limited traits, and can you give an example?

Sex-limited traits are those that are expressed in only one sex, even though both sexes carry the gene. A common example is lactation in cattle, which is dominant in females but never expressed in males due to hormonal differences.

What is the difference between sex-limited and sex-influenced traits?

Sex-limited traits are expressed in only one sex, whereas sex-influenced traits are expressed in both sexes but are more common in one due to hormonal influences. An example of a sex-influenced trait is baldness, which is more common in males than females.