Explore how a single DNA substitution changes the beta-haemoglobin sequence and causes sickle-cell effects on red cells and oxygen transport in IB Biology HL D1.2.11.
Explain the cause of sickle cell anemia and how this disease affects humans.
a. caused by a single nucleotide/base substitution mutation/GAG to GTG
b. «mutation of» a gene of β-globin/a subunit of hemoglobin
c. mRNA copies the mutation of DNA and substitutes an amino acid in hemoglobin «subunit»
d. glutamic acid is substituted by valine
e. sickle cell anemia involves distorted hemoglobin protein/HbS
f. «distorted HbS causes» distortion/sickling/shape change of red blood cells
g. «distorted/sickled red blood cells» block capillaries/blood flow
h. HbS/sickled red blood cells cannot carry enough oxygen «for the body»/leads to fatigue
i. low oxygen concentration seriously affects structure of HbS
j. homozygous «HbS/HbS» state causes severe anemia/death at low oxygen concentrations
k. heterozygous state has less anemia/minor effects/less effect of structure of hemoglobin OR heterozygous state only affected at high altitude/extreme exercise/low levels of oxygen
I. «heterozygous state» provides protection against malaria parasite/selective advantage in malaria areas