mechanism of sex determination

autosomes are all except

one of the homologous pairs of CHs

genosomes are the

X CH and the Y CH

homogametic is an individual that

forms gametes which all have the same type of sex CH

heterogametic is an individual forming

two kinds of gametes

XX-XY type- in mammals, certain insects including drosophila and in certain angiospermic plants

• the female posseses two X CHs (homo) and the male possesses one X CH and one Y CH (hetero)

ZW-ZZ type- in certain insects including abraxas and vertebrates such as fish, reptiles and birds

• the female sex has one Z CH and one W CH (hetero)

• the male sex has two Z CH (homo)

XX-X type- it is a special type of sex determination, typical for insects- bees wasps including habrobracon and termites

• the female sex id diploid XX (homo), while male sex is haploid X (homo)

• the Y CH does not occur at all in this type

• the males develop from unfertilized eggs- parthenogenesis