Pola Hereditas Part 2 : Pautan (Linkage)

Summary

In this educational video, viewers learn about genetic inheritance patterns, focusing on linkage and sex-linked traits. The video explains hemophilia, a blood clotting disorder inherited through the X chromosome, and explores the concepts of gene linkage and sex-linked inheritance using examples from both humans and animals. It discusses how genes located on the same chromosome tend to be inherited together and introduces specific disorders like hemophilia, color blindness, and hypertrichosis. Additionally, examples from Drosophila melanogaster and various human traits highlight how these genetic concepts apply in real-world genetics.

Takeaways

• 😀 Hemophilia is a genetic disorder caused by a deficiency in blood clotting factors (Factor 8 and 9) located on the X chromosome.
• 😀 Hemophilia is inherited in a recessive manner on the X chromosome and is more commonly seen in males, although females can also be affected in rare cases.
• 😀 Hemophilia can lead to excessive bleeding, which can occur spontaneously or as a result of trauma, affecting various organs like joints and the brain.
• 😀 Diagnosis of hemophilia involves medical history, physical examination, and blood tests to assess clotting factors and bleeding tendencies.
• 😀 Treatments for hemophilia include factor replacement therapy, and new research into gene therapy using adenovirus vectors may provide hope for future cures.
• 😀 Linkage (pautan) refers to the phenomenon where genes located on the same chromosome tend to be inherited together, as they do not separate independently during meiosis.
• 😀 Sex-linked inheritance, or linkage on sex chromosomes, is seen in diseases like hemophilia, where the gene for the disorder is carried on the X chromosome.
• 😀 The inheritance of sex-linked traits like hemophilia follows specific patterns, which can be understood through genetic crosses and family history.
• 😀 Hypertrichosis (Werewolf syndrome) is a rare condition where excessive hair growth occurs due to a mutation on the X chromosome, resulting in abnormal hair growth patterns.
• 😀 Inheritance of traits such as color blindness and anodontia (lack of teeth) follows sex-linked patterns, with these conditions being caused by mutations on the X chromosome.

Q & A

What is hemophilia and how is it inherited?

Hemophilia is a genetic disorder caused by a deficiency in blood clotting factors, specifically factors VIII and IX. It is inherited in an X-linked recessive pattern, meaning it primarily affects males, while females can be carriers. In some cases, females may manifest the disorder if both of their X chromosomes carry the defect.

What are the clinical symptoms of hemophilia?

The primary clinical symptom of hemophilia is excessive bleeding, which can occur spontaneously or as a result of trauma. Common areas for bleeding include joints, brain, retrofaringeal area, and retroperitoneal space. Hemophiliacs may also experience recurrent bleeding or difficulty stopping bleeding after trauma.

What is the role of genetics in hemophilia?

Hemophilia is linked to genes on the X chromosome, making it a sex-linked genetic disorder. The gene mutations responsible for hemophilia are recessive, and females may be carriers, passing on the defective gene to their offspring, while males who inherit the gene will express the condition.

What is genetic linkage and how is it related to hemophilia?

Genetic linkage refers to the phenomenon where two or more genes located on the same chromosome are inherited together because they are close to each other. In the case of hemophilia, the genes responsible for the condition are located on the X chromosome, making hemophilia an example of sex-linked genetic linkage.

What is the difference between autosomal linkage and sex-linked linkage?

Autosomal linkage occurs on non-sex chromosomes, where genes on the same chromosome tend to be inherited together. Sex-linked linkage, on the other hand, involves genes located on the X or Y chromosomes. Hemophilia is an example of sex-linked linkage because it is inherited through the X chromosome.

How does the inheritance pattern of hemophilia differ between males and females?

Males are more likely to inherit hemophilia because they have only one X chromosome. If the X chromosome they inherit carries the defective gene, they will express the disorder. Females, with two X chromosomes, can be carriers if one X chromosome carries the defective gene, but they usually do not express the disorder unless both X chromosomes are affected.

What is the significance of carrier females in the inheritance of hemophilia?

Carrier females have one X chromosome with the hemophilia gene and one normal X chromosome. Although they typically do not show symptoms of hemophilia, they can pass the defective gene to their offspring, which could result in hemophilia in male children or carrier status in female children.

What is hypertrichosis and how is it inherited?

Hypertrichosis, also known as Werewolf syndrome, is a rare condition characterized by excessive hair growth all over the body, including the face. It is caused by a mutation in a gene located on the X chromosome, which leads to abnormal hair growth patterns. It is inherited in a sex-linked manner.

How does color blindness relate to X-linked inheritance?

Color blindness is a condition often caused by a recessive gene located on the X chromosome. Males, having only one X chromosome, will express color blindness if they inherit the defective gene. Females must inherit the defective gene from both parents to express color blindness, though they can be carriers if they inherit only one faulty gene.

What is the genetic basis for Calico cats being predominantly female?

Calico cats have a unique coat pattern of three colors, and this trait is determined by genes located on the X chromosome. Since females have two X chromosomes, they can inherit the necessary genes for the calico pattern. Male calico cats are very rare and typically have an extra X chromosome (XXY), a condition called Klinefelter syndrome.