Chapter 9 Genetics

Why… When 2 giraffes mate, do you only get another giraffe? …. Why don’t you get a porcupine instead?

How come we look like Our parents and brothers and sisters?

Heredity= passing traits to offspring Traits= eye-color, hair-color, height, skin color, personality, diseases, etc. Offspring= what’s born, puppies, babies, kittens Genotype: what your DNA code says Phenotype: what shows on the outside

Alleles We use letters to represent traits when we study genetics. ½ chromosomes come from dad and ½ come from mom ….so 2 letters for every trait Ex: eye color= letter b B= brown b= blue

Dominant/ Recessive So the different combinations of those letters are… BB: genotype (carries 2 brown), phenotype (shows brown) Bb: genotype (carries both), phenotype (shows brown) bb: genotype (carries only blue), phenotype (shows blue)

So brown eyes were dominant … Figure 1: Forty shades of color.

Incomplete Dominance White + red= ______________ Curly + straight= ________________ CC Cc cc

Co- dominance CC Cc cc What do you think this means….

Co- dominance RR- brown Rr- white with brown spots rr- white Both traits are expressed at the same time