PKU as genetic disease
Phenylketonuria is a genetic disease due to a recessive allele. Mutation in autosomal gene (located in one of the 22 pairs of chromosomes rather than the 23 pair), coding for enzyme turning phenylalaine into tyrosine.
Leads to accumulation of phenylalaine and deficiency of tyrosine: impaired brain development, intellectual disability.
Phenotypic plasticity
Ability to convert a phenotype as an adaption to the environment around.
Ability of an organism to alter gene expression as a response to environment. (morphological, physiological, behavioural changes). morphological - form and strucutre. Physiological - what processes are involved.
Ex plant activating growth hormone to thincken leaves when much light is available.
Incomplete dominance
Neither allele is dominant over the other. Alleles mixed in the phenotype. The phenotype.
Typical ratio 1:2:1
Mark with Capital letter for the genotype and lower subheading for the phenotype.
Ex colour in flower Mirabilis Jalapa. Four o’clock flower.
Codominance
Both alleles are expressed in the phenotype, neither masks the other.
ABO groups.
I^A, I^B are dominant over i.
Coding for different glycoproteins in the red blood cell membrane.
Genotype A and B both glycoproteins expressed in phenotype. Antibodies are created to donor blood if antigen A or antigen B is not recognised as self. Type O does not have any addition to the glycoprotein and will always be recognised.
