Sex Determination and Linkage Quiz

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Questions and Answers

What determines maleness in humans and most other mammals?

The presence of two X chromosomes

The presence of the Y chromosome (correct)

The number of pairs of autosomes

The interaction of multiple genes

Which sex chromosome composition represents a normal male in humans?

XY (correct)

In the XY method of sex determination, what kind of gametes does the male produce?

Gametes that are identical

Two kinds of gametes (correct)

Gametes that lack sex chromosomes

Only one type of gamete

What is the role of the SRY gene in sex determination?

It activates the development of testicular tissue Signup and view all the answers

In heterogametic females of the ZZ-ZW method, what are the sex chromosomes for females?

ZW Signup and view all the answers

How is the Y chromosome significant in the context of Drosophila?

It carries genes active in sperm formation Signup and view all the answers

What term describes the inheritance patterns of genes located on the sex chromosomes?

Sex linkage Signup and view all the answers

What characterizes homogametic sex in humans?

Having two X chromosomes Signup and view all the answers

Which of the following is NOT a chromosomal sex-determining mechanism?

QQ Signup and view all the answers

What is the function of testis-determining factor (TDF) encoded by the SRY gene?

To promote testicular development Signup and view all the answers

What defines genes that are sex-linked?

Their expression and inheritance patterns differ between males and females. Signup and view all the answers

Which genetic condition is an example of an X-linked recessive disorder?

Duchenne Muscular Dystrophy Signup and view all the answers

Which statement about holandric genes is true?

They are transmitted only from father to son. Signup and view all the answers

Why are X-linked recessive disorders more common in males?

Males have only one X chromosome. Signup and view all the answers

In the context of X-linked dominant disorders, which statement is accurate?

Both males and females can be affected. Signup and view all the answers

Which of the following symptoms is associated with Hemophilia?

Prolonged bleeding Signup and view all the answers

How does the inheritance pattern of X-linked recessive disorders differ for affected males and females?

Affected males cannot pass the disorder to their sons but will pass it to all daughters. Signup and view all the answers

Which disorder primarily affects females and is considered an X-linked dominant condition?

Rett Syndrome Signup and view all the answers

What distinguishes X-linked genes from autosomal genes?

X-linked genes exhibit different inheritance patterns based on gender. Signup and view all the answers

What is a common feature of X-linked recessive disorders in terms of carrier females?

Carrier females have a 50% chance of passing the mutation to their children. Signup and view all the answers

Study Notes

Sex Determination and Sex Linkage

Sex determination is primarily controlled by genetic and hormonal factors.
Four types of chromosomal sex-determining mechanisms exist: XY, ZW, XO, and compound mechanisms.
In humans and most mammals, sex is determined by the presence of two different sex chromosomes (X and Y). These are heteromorphic, meaning they differ in size and shape.

XY Sex Determination Method

Males have 22 pairs of autosomes and one X and one Y chromosome. They produce two types of sperm: X-bearing and Y-bearing.
Females have 22 pairs of autosomes and two X chromosomes, producing only X-bearing eggs.
This system results in a 50/50 chance of the offspring being male or female.

Heterogametic Females (ZZ-ZW)

This method is found in many birds, butterflies, moths, and some fish.
Females are heterogametic (ZW) while males are homogametic (ZZ).
The mode is similar to the XY mechanism.

Sex Linkage

Sex linkage describes inheritance patterns of genes located on the sex chromosomes (X and Y).
Genes on sex chromosomes are called sex-linked.
Their expression and inheritance patterns differ between males and females.
Holandric genes are completely Y-linked, passing only from father to son.

X-Linked Disorders

Many human traits are X-linked, including color blindness, hemophilia, and Duchenne muscular dystrophy.
X-linked disorders are more prevalent in males since they have only one X chromosome.
Females can be carriers of X-linked recessive genes, but the trait more easily shows up in male offspring.

X-Linked Recessive Disorders

More males than females are affected. Affected males cannot pass the disorder to their sons, but all daughters will be carriers.
Carrier females have a 50% chance of passing the mutation to their offspring.
Examples include hemophilia (impaired blood clotting).

X-Linked Dominant Disorders

Both males and females can be affected.
Affected males pass the disorder to all daughters but not sons.
Affected females have a 50% chance of passing the disorder to their offspring
An example is Rett Syndrome

Fragile X Syndrome

A genetic condition causing intellectual disability, behavioral challenges, and distinctive physical features.
Symptoms include learning disabilities, developmental delays, social and behavioral problems.

Additional Information

Researchers like Henking, McClung, and Wilson investigated the relationship between chromosomes and sex determination.
The SRY (Sex-determining Region Y) gene is located on the short arm of the Y chromosome and is crucial for male development.

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Description

Test your knowledge on sex determination and sex linkage mechanisms. This quiz covers different chromosomal sex-determining systems such as XY and ZW methods, along with the concept of sex linkage in inheritance. Understand the impact of genetic and hormonal factors in determining sex.