Genes on the X Chromosome: *Sex chromosomes *Autosomes Example: In Drosophila and all mammals sex chromosomes designated as X and Y XX=female XY=male *1909 Thomas Hunt Morgan II III IV XX XY or
Genes on the X Chromosome:
Feb 11, 2016
II. III. XY. IV. or. XX. Genes on the X Chromosome:. *1909 Thomas Hunt Morgan. *Sex chromosomes *Autosomes. Example: In Drosophila and all mammals sex chromosomes designated as X and Y XX=female XY=male. Genes on the X Chromosome con’t:. *X-linkage. X-linkage in Drosophila : - PowerPoint PPT Presentation
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Genes on the X Chromosome:
*Sex chromosomes*Autosomes
Example: In Drosophila and all mammalssex chromosomes designated as X and YXX=femaleXY=male
*1909 Thomas Hunt Morgan
II III IV
XX
XY
or
*X-linkage
X-linkage in Drosophila: white mutation (eyes)
Genes on the X Chromosome con’t:
Sex-limited Inheritance:*Sex-limited trait
*holandric genes: genes on the Y chromosome
*autosomal genesExample: milk production in mammals; L=lots, l=little
*Sex-influenced trait
Sex-influenced Inheritance:
Examples:*cleft palate in humans*horns in sheep *pattern baldness in
humans
Summary:Sex-linked on X or Y sex-chromosomeSex-limited all or none expression by sexSex-influenced genotype + sex determines phenotype
Phenotypic Expression:
*Penetrance
*Expressivity
Gene expression often governed by genotype and environment
If 9/10 of individuals carrying an allele express the trait, the trait is said to be 90% penetrant
*Onset of genetic expression
*Temperature
Related Documents
