Allele Interactions

In organisms with chromosomal sex determination, what term describes the sex that has two different sex chromosomes, such as XY in humans or ZW in birds?

In birds, which chromosomal system determines sex, and which sex is heterogametic?

What is the primary function of the SRY gene in human embryonic development?

How is sex determined in the fruit fly, Drosophila melanogaster?

What is the key mechanism of dosage compensation in mammals?

What is a Barr body?

What is the genetic basis for the patchwork of orange and black fur in female calico and tortoiseshell cats?

Red-green colorblindness is an X-linked recessive trait. Why is this condition significantly more common in chromosomal males (XY) than in chromosomal females (XX)?

What are the pseudoautosomal regions (PAR) on the human X and Y chromosomes?

In Complete Androgen Insensitivity Syndrome (CAIS), an individual with an XY genotype has a female phenotype. What is the underlying molecular cause?

What is the key distinction between a sex-linked gene and a sex-influenced gene?

Approximately how many genes does the human X chromosome carry?

What is the expected outcome in a reciprocal cross involving an X-linked trait that is not seen with an autosomal trait?

Why are germline mutations in proto-oncogenes considered to be typically embryonic lethal?

In the case of 5-alpha-reductase deficiency, individuals with an XY genotype may appear to have female or ambiguous genitalia at birth but develop male secondary sex characteristics at puberty. What causes this change?

Which condition is a sex chromosome aneuploidy where an individual has only one X chromosome (XO)?

What is the primary reason that sex chromosome aneuploidies are more common and generally less severe than autosomal aneuploidies?

According to the text, what is the definition of a person's gender?

In the human sex determination pathway, what is the role of anti-Müllerian hormone (AMH)?

How can the study of reciprocal crosses in fruit flies, like those performed by Thomas Hunt Morgan, demonstrate that a gene is X-linked?

In birds, which use a ZZ/ZW system, the DMRT1 gene on the Z chromosome is critical for maleness. Why does a ZW individual develop as a female?

What is the term for a gene that is located on an autosome but is expressed differently in males and females, such as male pattern baldness?

What is the genetic karyotype of the vast majority of rare male tortoiseshell or calico cats?

Why do heterozygous females for X-linked hemophilia A typically not have the disease, despite half of their liver cells not producing Factor VIII?

What is meant by the term 'hemizygous' in the context of X-linked genes?

What is the primary factor that triggers the development of ovaries in a human embryo with an XX genotype?

According to the text, approximately what percentage of the human population is estimated to have a Difference of Sex Development (DSD) when atypical sex chromosome ploidy is included?

An individual with Klinefelter syndrome has which sex chromosome genotype?

What does 'skewed X-inactivation' refer to, and what can be its consequence?

In the human sex determination pathway, genes like WNT4 and RSPO1 are essential for which process?

What is the key difference between a sex-limited trait and a sex-influenced trait?

In Congenital Adrenal Hyperplasia (CAH), a mutation in the 21-hydroxylase enzyme leads to what hormonal imbalance and resulting phenotype in XX individuals?

Why do chromosomal males (XY) always express the phenotype determined by their single allele for an X-linked gene?

A rare condition in humans is caused by a translocation of the SRY gene onto an X chromosome. What would be the expected chromosomal sex and phenotypic sex of an individual who inherits this X chromosome and a normal X chromosome from their other parent?

How many rows and columns would a Punnett square for a three-gene cross have, and how does this relate to the challenge of using them for multigene problems?

Which dosage compensation mechanism is employed by the roundworm C. elegans?

In the developmental cascade leading to a male phenotype in humans, which gene is directly activated by the SRY transcription factor?

Why are true Y-linked traits considered very rare in humans?

What is the developmental fate of the Müllerian ducts in a typical XY human embryo?

What happens to the Wolffian ducts in a typical XX human embryo?

What is the typical cause of Swyer syndrome, which results in an XY individual with a female phenotype?

According to Thomas Hunt Morgan's work, what did the results of reciprocal crosses for the 'white' eye color trait in Drosophila demonstrate?

If a female cat is homozygous for the black allele (O_B O_B) of the X-linked fur color gene, what will her phenotype be?

In the absence of a Y chromosome, what is the default phenotypic outcome for a human embryo regarding sex development?

What causes the different forms of red-green color blindness, such as protanopia and deuteranopia?

Why do individuals with an XYY genotype have a male phenotype?

A female is heterozygous for an X-linked recessive trait. Under what circumstances might she display the recessive phenotype?

How can X-inactivation in mammals be considered a form of epigenetic modification?

Why do true Y-linked traits have no dominant or recessive forms?

What is the consequence of a loss of function mutation in the 'white' gene in Drosophila melanogaster?