Please enable JavaScript.
Coggle requires JavaScript to display documents.
16.7 Genes, proteins and phenotype - Coggle Diagram
16.7 Genes, proteins and phenotype
Albinism
-
-
-
-
Tyrosinase converts the amino acid tyrosine to DOPA and then dopaquinone, which is converted to melanin
If tyrosinase is absent or inactive, tyrosine is not converted into DOPA and then dopaquinone, so no melanin is formed
Sickle cell anaemia
-
-
Single base substitution resulting in faulty codominant allele for beta-globin gene (part of haemoglobin molecule)
When not combined with oxygen, the haemoglobin is much less soluble and sticks together inside the RBC
RBCs form long internal fibres, distorting their shape into a sickle shape which gets stuck in capillaries
Sickle-shaped cells also lose the ability to transport oxygen, causing anaemia (lack of oxygen in cells)
Haemophilia
-
F8 found on non-homologous region of X chromosome, so is sex-linked
-
People with haemophilia bleed excessively from even small injuries, as their blood does not clot
-
Huntington's disease
-
-
-
If number of CAG triplet repeats (or 'stutters') is over 40, then the person develops Huntington's
Symptoms only develop after around 30 years of age, so people may have children without knowing they have Huntington's and then pass on the disease
Plant dwarfism
Gene/alleles: Le (dominant), le (recessive)
-
Gibberellin stimulates cell elongation and division, so plants homozygous with le which cannot produce gibberellin remain short