Class 6 - Sex chromosomes and their effects Readings: Ch. 3...

Info iconThis preview shows pages 1–17. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Sex chromosomes and their effects Readings: Ch. 3 pp. 54-58; Ch 7 pp 164-165 2 Chromosomal basis of sex determination The inheritance of particular chromosomes determines sex in many species How was this discovered? 2 3 Cytogenetics Cytogenetics = study of chromsomes using microscopy Observed that in may species (i.e. human) males have different constitution of chromosomes that females In human, called X and Y, male has XY ALWAYS and female has XX always 3 4 Pictorial representation of chromosomes = karyotype 5 Definitions Heterogametic sex has two different sex chromosomes (XY) Homogametic sex has one or two of one of the sex chromosomes Non-sex chromosomes are Autosomes Human gametes have 22 autosomes and 1 sex chromosome 5 6 Morgan First Genetics Nobel prize for this! Discovered white-eyed fly (normally red) Did some test crosses 6 7 Did the following cross What is likely genotype of F1 female? A. w + w + B. w + w C. ww D. This is a new mutation 7 7 Did the following cross What is likely genotype of F1 female? A. w + w + B. w + w C. ww D. This is a new mutation 7 8 Intercrossing F1 flies you e What is the predicted ratio red-eyed flies to white- eyed? A. 3:1 B. 1:1 C. 1:3 D. cannot predict 8 8 Intercrossing F1 flies you e What is the predicted ratio red-eyed flies to white- eyed? A. 3:1 B. 1:1 C. 1:3 D. cannot predict 8 9 Sorta got that result but.... All female flies had red eyes while males were 1:1 Can you explain this? 9 9 Sorta got that result but.... All female flies had red eyes while males were 1:1 Can you explain this? 9 10 So what do you predict for the following cross? A. 3:1 male/3:1 female B. 1:1 male/3:1 female C. 3:1 male/1:1 female D. 1:1 male/1:1 female 10 ? 10 So what do you predict for the following cross? A. 3:1 male/3:1 female B. 1:1 male/3:1 female C. 3:1 male/1:1 female D. 1:1 male/1:1 female 10 ? 11 X-linked traits give simplified inheritance patterns 12 What is the nature of the sex chromosomes in humans?...
View Full Document

Page1 / 38

Class 6 - Sex chromosomes and their effects Readings: Ch. 3...

This preview shows document pages 1 - 17. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online