Inheritance

Gene

  • Sequence of neuclotide, control the production of a polypeptide
  • Unit of inheritance

Allele

  • Alternative form of a Gene

T - tall allele t - dwarf allele Same Gene - Height of plant

B - blue iris b - black iris Same Gene - Colour of iris

Terms

Dominant

  • Always express
  • Capital letter B, T

Recessive

  • Only express when homologous recessive, bb, tt

Codominant

  • Blood type

Homozygous

  • Same allele

Hetrozygous

  • Different allele

Phenotype

  • Outward apparent
  • Tall, blue iris

Genotype

  • Genetic made up
  • Tt, TT, Bb

Genetic Diagram

Hetrozygous x Hetrozygous

  • Tt Tt Tt tt
  • 3:1

Hetrozygous x Homozygous

  • Tt tt Tt tt
  • 1:1

Doesn't follow ratio?

  • Small number of progeny

Sex

Male

  • XY

Female

  • XX

1/2 probability, not affected by 1st child 2nd child

Mutation

Causes

  • Radiation
    • X-ray
    • Gamma ray
  • Chemical
    • Tar
    • Mustard gas

Gene

  • Albine
  • Sickle Cell Anemia

Chromosome

  • Down syndrome
  • One more chromosome

Variation

Continuous

  • Gene + environment
  • Mass, height, skin colour, IQ
  • Range/mean, intermediate

Discontinuous

  • Gene
  • Blood type, Colour of Iris
  • Discrete

Natural Selection

  • Random Mutation lead to Genetic Variation
  • Competition (food / fire resistance / drought resistance)
  • Differential survival
    • Selective advantage / Selection pressure
  • Survival & Reproduce
  • Pass down the favorable gene to the next generation
  • Lead to Natural Selection
  • Billion years for the accumulation of different characteristics/features

Artificial Selection

Human decides, Commercial values

  • 2 Parents
    • Drought resistant wheat x High yield wheat
  • Select the hybrid that have the characteristics
  • Discard the unwanted
  • Repeat process for many generations (time consuming)

Backlinks

Biology