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Ch. 7 - Sex Determination and Sex Chromosomes
Klug - Concepts of Genetics  12th Edition
Klug12th EditionConcepts of Genetics ISBN: 9780135564776Not the one you use?Change textbook
Chapter 7, Problem 3

Distinguish between the concepts of sexual differentiation and sex determination.

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1
Define sex determination as the biological process that establishes the genetic and chromosomal basis of an organism's sex, typically occurring at fertilization when sex chromosomes are inherited (e.g., XX for female, XY for male in humans).
Explain sexual differentiation as the subsequent developmental process by which the undifferentiated gonads and reproductive structures develop into male or female phenotypes, influenced by genetic, hormonal, and environmental factors.
Highlight that sex determination is the initial step that sets the genetic sex, while sexual differentiation is the cascade of events that lead to the physical and physiological traits associated with that sex.
Provide examples: in humans, sex determination involves the presence or absence of the SRY gene on the Y chromosome, whereas sexual differentiation involves the development of testes or ovaries and secondary sexual characteristics.
Summarize by emphasizing that sex determination is about 'what sex an organism is genetically,' and sexual differentiation is about 'how that genetic sex is expressed in the organism's body.'

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Sex Determination

Sex determination is the biological process that establishes the genetic or chromosomal sex of an organism, typically at fertilization. It involves mechanisms like the presence of sex chromosomes (e.g., XY in males, XX in females) that dictate whether an individual develops as male or female.
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Sexual Differentiation

Sexual differentiation refers to the developmental process by which the undifferentiated gonads and reproductive structures develop into male or female phenotypes. This includes the formation of internal and external genitalia and secondary sexual characteristics influenced by hormones.
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Relationship Between Sex Determination and Sexual Differentiation

Sex determination sets the genetic foundation for sex, while sexual differentiation is the downstream process that translates this genetic information into physical and physiological traits. Understanding their distinction clarifies how genetic sex leads to phenotypic sex.
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