* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Document
Sexual dimorphism wikipedia , lookup
Pathogenomics wikipedia , lookup
Genomic library wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Hybrid (biology) wikipedia , lookup
Essential gene wikipedia , lookup
Genome evolution wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Gene expression profiling wikipedia , lookup
Ridge (biology) wikipedia , lookup
Gene expression programming wikipedia , lookup
Dominance (genetics) wikipedia , lookup
Biology and consumer behaviour wikipedia , lookup
Minimal genome wikipedia , lookup
Skewed X-inactivation wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
Designer baby wikipedia , lookup
Microevolution wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Genome (book) wikipedia , lookup
Y chromosome wikipedia , lookup
Neocentromere wikipedia , lookup
Epigenetics of human development wikipedia , lookup
7.1 Chromosomes and Phenotype • The chromosome theory of inheritance follows Mendel’s laws of segregation and independent assortment. • We give much credit to Thomas Hunt Morgan and his work with fruit flies- Drosophilia melanogaster in the early 20th century – Wild vs mutant types – Sex linked genes (on X chromosome) – Linkage between genes (possibly due to crossing over/recombination) 7.1 Chromosomes and Phenotype Males and females can differ in sex-linked traits. • Genes on sex chromosomes are called sex-linked genes. – Y chromosome genes in mammals are responsible for male characteristics. About 78 genes (code for about 25 proteins) – X chromosome genes in mammals affect many traits. 7.1 Chromosomes and Phenotype – Fathers pass sexlinked alleles to all daughters, but no sons. – Mothers can pass sex-linked alleles to daughter and sons. – More males than females have sexlinked recessive disorders 7.1 Chromosomes and Phenotype • Sex-linked recessive disorders: – Color blindness – Duchenne muscular dystrophy – Hemophilia 7.1 Chromosomes and Phenotype X Inactivation – One X chromosome in each cell in females becomes almost completely inactivated during embryonic development. (males=females) – X in each cell of a female condenses to make a Barr body (later reactivated to make eggs) 7.1 Chromosomes and Phenotype • X-inactivation is not the same as genomic imprinting. • Genomic imprinting occurs during formation of gametes and results in the “silencing” of one allele of a certain gene. • This means that certain traits will depend on which parent passed down silent alleles. • Geneticists have identified about 2000-3000 of these traits in mammals.