MBLG2972 Lecture Notes - Lecture 5: Testis Determining Factor, Dosage Compensation, X-Inactivation
5 Jul 2018
School
Department
Course
Professor
MBLG2072
Genetics and Genomics
Monica Zanuttini !
460381099
Lecture 5 Sex linkage and sex determination
Sex linked inheritance: !
Sex-linked inheritance refers to the hereditary transmission of genes on the sex
chromosomes. !
Human X and Y chromosomes: !
X is larger (165 Mb) while Y is smaller (58 Mb). !
Pseudoautosomal regions allow them to join in meiosis. !
!
Sex linked genes: !
Thomas Hunt Morgan discovered white eye mutant
of Drosophila, thus sex-linkage. !
Red eye female x White eye male !
F1 = all red eye.!
F2 = 3/4 Red eye and 1/4 white eye males (no
white eyed females). !
Female red eye (carriers) x White eye male!
F1 = 25% female WT, 25% female M, 25% male WT, 25% male M. !
(females can genetically and phenotypically have white eyes) !
Reciprocal crosses: !
Summary: !
Inheritance of X-linked traits produces
different outcomes in reciprocal crosses !
Males are hemizygous!
Females are homozygous or heterozygous !
Males inherit X chromosomes from their
mothers and transmit X chromosomes to
their daughters. !
Nondisjunction: Failure in chromosome separation during meiosis.
Document Summary
Sex-linked inheritance refers to the hereditary transmission of genes on the sex chromosomes. X is larger (165 mb) while y is smaller (58 mb). Pseudoautosomal regions allow them to join in meiosis. Thomas hunt morgan discovered white eye mutant of drosophila, thus sex-linkage. F2 = 3/4 red eye and 1/4 white eye males (no white eyed females). Female red eye (carriers) x white eye male. F1 = 25% female wt, 25% female m, 25% male wt, 25% male m. (females can genetically and phenotypically have white eyes) Inheritance of x-linked traits produces di erent outcomes in reciprocal crosses. Males inherit x chromosomes from their mothers and transmit x chromosomes to their daughters. Drosophila the x chromosome number determines sex. Humans and other mammals - the y chromosome determines sex. Sex determination in drosophila more accurately is determined by the ratio of sex chromosomes to autosomes.
