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Unformatted text preview: (Drosophila melanogaster).
- Observed unusual patterns of inheritance - reciprocal
crosses did not give same results.
Example: Eye color in fruit flies
red-eyed female x white eyed male F1: all red-eyed
white-eyed female x red-eyed male F1: all females red-eyes
all males white eyes Sex Chromosomes
- In mammals and some other groups:
females: 2 X chromosomes (XX)
males: 1 X & 1 Y chromosome (XY).
- X larger, carries more genes.
Pair not homologous.
- Non-sex chromosomes =
autosomes. Sex Chromosomes And Gamete Formation
- Pair at meiosis I, segregate into different gametes.
- All female’s eggs carry one X
1/2 sperm carry an X, and 1/2 carry a Y. Inheritance Of X-Linked Genes
- Genes carried only on X, not on Y “X-Linked”
* Females: 2 copies of gene (one from each parent)
Males: 1 copy (from mother).
- Use Punnet squares: female gametes - Xa
male gametes - Y no allele
So, can we ex...
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This note was uploaded on 02/24/2014 for the course BIOL 180 taught by Professor Freeman during the Winter '07 term at University of Washington.
- Winter '07