Patterns of Inheritance

1
Patterns of Inheritance
2
Simple Mendelian

• Controlled by dominant and recessive paired
  alleles

3
Complex Patterns of Inheritance

• Incomplete dominance
• The phenotype of the heterozygote is intermediate
  between those of the two homozygotes
• Ex. Red snapdragon X white snapdragon pink
  snapdragon

4

• Codominance (BW)
• Phenotypes of both homozygotes are produced in
  heterozygote and alleles are expressed
• BW both black and white will show

5

• Multiple alleles
• Traits are controlled by more than one allele
• Rabbit fur, human blood type

cch (chincilla)
Dominant C (gray)
Recessive c (white)
ch (Himalaya)
6

• Ex. Blood type

7

• Sex determination
• 22 pairs of autosomes
• 1 pair of sex chromosomes

8

• Sex-linked inheritance
• Traits controlled by sex chromosomes
• Ex. hemophilia, color blindness

9

• Polygenic inheritance
• Traits are controlled by different genes
• Ex. human height, skin color

10
Environmental Influences of gene expression

• Internal age, sex (male or female)
• External temperature, nutrition, light,
  chemicals, and infectious agents

11
Determining genotypes

• Testcross
• A cross between an individual of unknown genotype
  with an individual of know genotype
• Usually the known test organism is homozygous
  recessive (rr) for the trait in question
• Carrier a heterozygous individual (Rr)
• Pedigree
• A graphic representation of an individuals
  family tree

12
(No Transcript)