Summary of Inheritance Patterns
Type of
inheritance
(Mendel’s)
Dominant
recessive
Sex linked
Co-dominance
Incomplete
dominance
Multiple
alleles
Description
Example(s)
Gene is on one of the autosomes
1. Plant height
(chromosome 1 to 22 in humans), 2 different 2. Pea colour for peas
alleles, in the heterozygous genotype 1 allele
dominates the other
Gene is on one of the 2 sex chromosomes
1. Haemophilia
(usually the x)
(blood disorder)
- Only females can be heterozygous
2. Colour blindness
Heterozygous genotype shows a third
1. Coat patches i.e.
phenotype
black + white
cows
1. AB Blood group
Heterozygous genotype shows a third
1. Flower colour i.e.
genotype  blending
snap dragons
3 or more alleles to inherit (but every
1. ABO blood group
organism only inherits 2)
Phenotypes
1. Pea plants Tall or
Short
2. Pea colour Green or
Yellow
Females can be carriers
(not males with only 1 X
chromosome)
2. Black, white,
black/white
patches
Genotypes/Alleles
1. TT=tall, Tt=tall, tt=short
2. GG=green, Gg=green, gg=yellow
1. XH XH = No Haemophilia, XH Xh = No
Haemophilia, Xh Xh = Haemophili, XH Y = No
Haemophilia, Xh Y = Haemophilia
1. BB = Black, WW = White, BW = Black/white
2. Red, pink, white
1. RR = Red, WW = White, RW = Pink
2. AB, A, B, O blood
types
1. IA IB, IA IA or IA I, IB IB or IB I, ii