Study Guides (248,269)
Canada (121,449)
Biology (174)
BI226 (18)

Chapter 5 Notes.docx

2 Pages
Unlock Document

Robert Boulianne

Chapter 5 – Sex Determination and Sex Chromosomes • Heteromorphic Chromosomes – Eg. X and Y • Unisexual, dioecious and gonochoric – Contain only male OR female reproductive organs • Bisexual, monoecious and hermaphroditic – Contain both male AND female reproductive organs • Intersex – Individuals of intermediate sexual differentiation…usually sterile Modes of Sex Determination • Protenor mode (XX & XO) • Lygaeus mode (XX & XY) or (ZZ & ZW) • In both cases one sex produces two types of gametes (heterogametic sex) while the other produces only one type of gamete (homogametic sex). Klinefelter Syndrome 47,XXY • Testes underdeveloped and fail to produce sperm • Tall, long arms & legs, large hands & feet • Slight decrease in intelligence (below normal range) • Result of nondisjunction event in parent Turner Syndrome 45,XO • Female external genitalia and internal ducts • 1 in 10,000 female births • Ovaries not fully developed • Short stature, skin flaps on back of neck and underdeveloped breasts. Shield-like chest. • Intelligence is normal • Result of nondisjunction event in parent. 47,XXX Syndrome • Occurs in about 1 of every 1,200 female births. • Observe variable expression: – Some XXX individuals are phenotypically normal, while others show underdeveloped secondary sex characteristics and mental retardation can occur. • Also see 48,XXXX and 49,XXXXX individuals…more pronounced symptoms 47,XYY Condition • Phenotypically male, usually over 6 feet tall, sometimes associated with lower intelligence and behavioral problems. The Y Chromosome • Originally thought not to have genes or homology to other chromosomes. – Pseudoautosomal regions (PARs) share homology with X chromosome • Allow pairing during meiosis – The rest of the chromosome is called the male-specific region of the Y (MSY) • Some genes in common with X, and some novel genes • There is at least one very important gene that determin
More Less

Related notes for BI226

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.