BIOL 443 Lecture Notes - Lecture 7: Sex-Determination System, Splicing Factor, Allosome
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I(cid:374) ge(cid:374)eral, ea(cid:272)h (cid:272)ell (cid:373)akes its o(cid:449)(cid:374) se(cid:454)ual (cid:862)de(cid:272)isio(cid:374)(cid:863) Thus, the protein is non-functional in males: sxl is also required for dosage commendation in females. Xx flies with sxl mutants die from too much transcription of the x chromosome. Active sxl binds to the transformer transcript, resulting in female-specific splicing and making a functional protein: the male splice form of transformer contains a stop codon and is nonfunctional. Sex determination in reptiles: sex chromosomes determine the sex of most lizards and snakes. It"s the e(cid:373)(cid:271)r(cid:455)o(cid:374)i(cid:272) e(cid:374)(cid:448)iro(cid:374)(cid:373)e(cid:374)ts that deter(cid:373)i(cid:374)es the se(cid:454) of (cid:373)ost turtles a(cid:374)d all crocidiles: temperature at a certain period of development influences sex. Sometimes, males only or females only arise within a given range of temperature. Temperature can also override chromosomal sex determination. Some xx lizards become male at low temps) Sex determination in plans: some plants are dioecious, and develop only one type of flower (male or female)
