BIOLOGY 2C03 Lecture Notes - Lecture 11: Transferase, Pyrimidine, Adenine

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graycrab987

23 Apr 2016

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The number of x chromosomes and their relation to the number of haploid sets of autosomal chromosomes are critical in determining sex. Flies with sex chromsomes xy, xyy and xo are all males. Ration of x chromsomes:# haploid sets of autosomes: 1x:2a in males, 2x:2a in females. Proteins controls the expression of the sex-lethal gnes (sxl) in xx flies. Placentals: tow kinds of sex chromosomes, but sex depends on the presence of absence of y. A single gene on the y chromosome: sry( sex-determining region of y), initates a series of events that lead to male sex phenotype in the embryo. Syr produces the transcirtion factor protein testes determining factor (tdf) causing a cascade that leads to development of male internal and external organs. Mammalian embreyos have twin clusters of tissues known as undifferentiated gonads which will develop into testes or oavaries.

Related Questions

How do we know that Drosophila utilizes a different sex-determination mechanism than mammals, even though it has the same sex-chromosome compositions in males and females?

Check all that apply

XXY flies being female (given the normal set of autosomes) implies that that the critical factor in sex determination is the ratio of X chromosomes to the number of haploid sets of autosomes.

XO flies being male (given the normal set of autosomes) implies that that the critical factor in sex determination is the ratio of X chromosomes to the number of haploid sets of autosomes.

XO flies being female (given the normal set of autosomes) implies that that the critical factor in sex determination is the ratio of X chromosomes to the number of haploid sets of autosomes.

XXY flies being male (given the normal set of autosomes) implies that that the critical factor in sex determination is the ratio of X chromosomes to the number of haploid sets of autosomes.

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11) CIRCLE ALL CORRECT ANSWERS: Human males are hemizygous for

a) Sxl gene b) pseudoautosomal region of the Y c)SRY d) gene for testis determining factor e) Xist gene

12) The X inactivation center codes for

a) gonadal ridges to form ovaries b) gonadal ridges to form testes c) RNA d) testosterone e) protein enhancing transcription of sex linked genes

13) CIRCLE ALL CORRECT ANSWERS: The pseudoautosomal region is found on

a) autosomes in males b) autosomes in females c) X chromosome d) Y chromosome e) both the X and Y chromosome f) could occur in fruit flies

14) Comparing two monozygotic XX twins to two monozygotic XY twins

a) XX are more identical b) XY are more identical c) monozygotic twins do not occur

EXPLAIN YOUR ANSWER:

15) CIRCLE ALL CORRECT ANSWERS: Butterflies and Habrobracon differ in

a) which sex is homogametic b) which sex is monoploid c) one has sex chromosomes and the other does not d) one produces some gametes by mitosis, the other does not

BIOLOGY 2C03 Lecture Notes - Lecture 11: Transferase, Pyrimidine, Adenine

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