Concept 9 Specialized chromosomes determine sex.
Excerpt of 1906 letter from W. Spillman to the American Breeders Association. The letter summarizes "recent" discoveries in genetics. Boxed text talks about Wilson's work on sex determination.
Nettie Maria Stevens, 1904.
Nettie Stevens at work in Naples, Italy, 1909.
Edmund Beecher Wilson, 1925.
Edmund Beecher Wilson, signed, 1925.
Historically, and in many cultures even now, women are blamed for not having sons. This is unreasonable since the sex of the child is determined by the father not the mother.
It is possible to have XXX or X females and XXY males. But there is no case of a living Y male. Why not?
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Excerpt of 1906 letter from W. Spillman to the American Breeders Association. The letter summarizes "recent" discoveries in genetics. Boxed text talks about Wilson's work on sex determination.
Children resemble their parents.
Genes come in pairs.
Genes don't blend.
Some genes are dominant.
Genetic inheritance follows rules.
Genes are real things.
All cells arise from pre-existing cells.
Sex cells have one set of chromosomes; body cells have two.
Specialized chromosomes determine sex.
Chromosomes carry genes.
Genes get shuffled when chromosomes exchange pieces.
Evolution begins with the inheritance of gene variations.
Mendelian laws apply to human beings.
Mendelian genetics cannot fully explain human health and behavior.