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To form a female zygote, the sperm cell must contribute which chromosome(s)?
The necessary genotype for a female zygote is XX.
The mother will share this XX genotype (since she is also female) and will contribute one X-chromosome. The father, however, will be male and have the genotype XY. This means he has a 50% chance of passing on an X-chromosome and a 50% chance of passing on a Y-chromosome. If the zygote inherits a Y-chromosome from the father's sperm, then the offspring will be male. If the zygote inherits an X-chromosome from the father's sperm, then the resulting genotype will be XX and the offspring will be female.
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What is a totipotent cell?
Totipotent cells have the ability to propogate and differentiate into any cell types, including the trophoblast. They are different from stem cells, which could be considered multipotent (able to differentiate into multiple tissue types) or pleuripotent (able to differentiate into any major tissue type, but cannot create trophoblast). The only truly totipotent cells are the first two blastomeres.
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What is the "common dogma"?
Most cells contain a complete genome, but not all genes are activated in each cell. Activation of particular genes produces appropriate protein function.
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Differentiation of the endoderm in a developing human embryo will eventually give the human the ability to __________.
The endoderm develops into a number of internal organs, including the lung, which are vital for breathing.
The kidneys (urine production), muscles (movement), and blood vessels (blood circulation) develop from the mesoderm. The brain (thought) develops from the ectoderm.
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