BIOL1006 Lecture Notes - Lecture 17: Heterogametic Sex, Chromosome Abnormality, Y Chromosome
24 Jul 2018
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Document Summary
Evolutionary importance of sex body cells are called autosomes sex chromosomes are to do with sex result from amniocentesis suck out amniotic uid to evaluate chromosomes. Homogametic (females are heterogametic in butter ies and birds) Males produce 2 types of sperm : x-bearing and y-bearing. Observed sex ratios do not equal as expected. Expectation : ratio of males:females to be 1:1. A gene that somehow distorts sex ratio. Meaning that the females are more available. Better choice of males to mate with. Or if the females are produced more. Then a female who can produce male offspring is favoured. Pushes evolution and stabilises it into a 50:50 ratio. Badgers at birth are much heavier at conception but they decline further with age. Sociologically: there are areas in the world where there are more male than females and vice versa. 17% more boy being born and kept than girl. In india 13% favour for boys than girls.
