Linkage and Recombination

Linakge

linear order of genes in a chromosome

Chiasmata

cross-like structure where two non-sister chromosomes of the homologous pairs crossover and exchange parts

Homologous chromosomes

from the two parents, similar but not the same

Sister chromosomes

identical copies of chromosomes from the same parent

Recombination happens between

homologous chromosomes

Sex-linked traits

genes at sex chromosome

Sex-limited traits

genes at autosomes, limited to that sex

ex. egg production, barred coloring only in roosters

Sex-influenced traits

genes at autosomes, an allele dominant in gender but recessive in another gender

ex. early pattern baldness in men bc testosterone causes it

Pullet

primary feathers longer than coverts

Cockerel

primaries smaller than on wing of pullet and same size as coverts

Dwarf: sex linked traits

recessive allele, dw in Z chromosome, a mutation in growth hormone receptor

causes lack of growth hormone effects even though production is normal

• females will always have it bc they are ZW