Genetics exam 2

homogametic

2 copies of the same sex chromosome, x in many

heterogametic

1 copy of each sex chromosome ( x and y in many)

sex determination genes

located on sex chromosomes and autosomes

sex determined traits

traits that dev. from sex determination genes such as gonads, external genitalia

sex influenced traits

traits controlled by autosomal genes but sex characteristics impact their expression, ex. male pattern baldness

sex limited traits

traits limited by sex, ex. milk production

sex linked traits

phenotypes that are controlled by genes on sex chromosomes, but not related to sex determination

X inactivation

mammals w more than 1 X chromosome inactivate the others in each cell - very condensed chromatin creates a Barr body that is not expressed

occurs randomly during embryonic development, makes tortoiseshell cats

sex sorting semen

since sperm is sex determining gamete in mammals, smaller size of y chromosomes enables sex-sorting

are sex chromosome or autosomal chromosome aneuploidies more common

sex

true breeding

subset of a species that displays the same phenotype over several generations

the law of equal segregation

the two copies of a gene segregate or separate from each other during the process that gives rise to gametes

allele pairs then randomly unite at fertilizations

dihybrid crosses

uses plants that bred true for 2 traits

law of independent assortment

2 different genes will randomly assort their alleles during formation of haploid cells, doesn’t apply in case of linkage