Transcript Sickle-cell anemia

Evolution through mutation?
Sickle-cell anemia
sickle-cell anemia is
caused by a single
amino acid mutation in
the hemoglobin gene;
evolutionists claim this
is an example of
evolution
Hemoglobin: protein in red
blood cells that carries oxygen
throughout the body
http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html
Children with “sickle
cell trait (HbAS) [have]
a slight survival
advantage to malaria
over those without the
mutation” (HbAA)
(CDC)
However, children with
sickle cell disease
(HbSS) have the lowest
chance of survival,
because sickle cell
anemia is often deadly.
What is Malaria?
•
http://www.malariasite.com/malaria/LifeCycle.htm
http://www.nytimes.com/2011/11/15/health/biochemistry-scientists-decode-the-protective-element-sickle-cell-anemia-offers-against-malaria.html
What is Sickle Cell Anemia?
- molecules of sickle-cell hemoglobin stick to one
another, forming rigid rods.
- sickled cells do not carry oxygen well and tend to
clog capillaries, leading to the blood supply being
cut of organs like the brain and heart.
- slight exertion can lead to heart attack or stroke.
http://www.nature.com/scitable/topicpage/genetic-mutation-441
Is Sickle-Cell really a good example for Evolutionists to use?
• Only one base (adenine to
thymine) changes in sickle
cell anemia; the beta globin
portion of hemoglobin alone
has 147 amino acids, coded
for by 147 codons, which
have 3 bases each. So its
about 1/141 base pairs.
• Sickle cell anemia is not
really a solution to malaria,
as those who get both
genes (25%) are more likely
to die, and those who get
one gene (50%) are only
slightly resistant to malaria.
Sickle Cell Inheritance
Look at the picture.
What type of trait is
sickle cell anemia?
Sickle cell anemia is a dominant-recessive
trait
Is sickle cell anemia
dominant or recessive?
Recessive. The child has to receive to sickle
Cell from both parents.
• How many codons are there in
hemoglobin?
Hemoglobin has 4 subunits, two called betaglobin, and the other two alpha-globin. Betaglobin is a single chain of 147 amino acids,
which means just the beta-globin portion of
hemoglobin has 147 codons.
What happens if there is mutation in another
codon of beta-hemoglobin?
– Some mutations have no effect: GluB26  Lys
– Some increase or reduce oxygen holding abilities: AspB99 
His & AsnB102  Thr
– More than 250 mutations in the beta-globin portion cause beta
thalassemia, which disrupts red blood cell development,
preventing these cells from carrying sufficient oxygen, leading to
poor growth, organ damage, etc…
– Methemoglobinemia, beta-globin type
• http://ghr.nlm.nih.gov/gene/HBB