6.1.2 Patterns of Inheritance- Dihybrid Crosses and co-dominance using TM

23 pairs of chromosomes (1 from each parent) at different loci of chromosomes which find genes which code for proteins that are characteristics and can be homozygous or hetrozygous for that gene as each allele has one from each parent

Expressing the dominant one over the recessive

Genotype- Two alleles for the characteristic

Phenotype- Physical feature of the genotype

Dihybrid is the inheritance of two characteristic from two different gene son different chromosomes

Round is dominant over recessive wrinkled

Yellow is dominant over recessive green

F1 generation is a pure breeding (Homozygous) RRYY rryy

All offspring are hetrozygous (Round and yellow)

F2 generation all gametes for F2 are RY Ry rY ry

Ratio: 9:3:3:1

This is due to random segregation when the line up randomly in meiosis, random fertilization, crossing over

Co-dominance is when you have two alleles that are equally dominant so they both express

E.g Flowers

R- is dominant

W- is also dominant

If its RW isn’t now pink as its a mixer of both dominant alleles

In a 1:2:1 ratio