Read the Edvotek procedure. The following diagram illustrates the potential
hemoglobin genotype of two individuals who are heterozygous for the
sickle cell gene. In order for a child to have the disease they must
inherit a hemoglobin S gene from each parent. This is why it is recommended
that individuals at risk for sickle cell disease be tested prior to
having children. If the parents are heterozygous there is a 25% chance
that the child will be homozygous for S and inherit the disease.
Distance Learning Students
The gel below demonstrates the expected results and contains the following:
Lane 1:
Control sample for Sickle cell patient
No restriction enzyme site is available in either of the two copies
of the gene. No restriction enzyme digestion of either gene. The pattern
will be one band on electrophoresis.
Lane 2:
Control sample for heterozygous Sickle cell trait
One of the pair of genes (the normal gene) contains the restriction
enzyme site. This gene is cut by the restriction to produce two smaller
pieces of DNA. The second copy of the gene has a mutation within the
palindrome. This change does not allow the enzyme to cut the mutated
gene into two smaller pieces. The pattern will yield three DNA bands
on electrophoresis.
Lane 3:
Control sample for Normal homozygous patient
Both normal genes contain the restriction enzyme palindrome and both
genes are digested to give the two smaller DNA bands.
Lane 4:
Mother DNA sample analysis
The mother is heterozygous for the sickle trait. One of the pair of
genes (the normal gene) contains the restriction enzyme site. This gene
is cut by the restriction to produce two smaller pieces of DNA. The
second gene has a mutation within the palindrome. This change does not
allow the enzyme to cut the mutated gene into two smaller pieces. The
pattern will yield three DNA bands on electrophoresis.
Lane 5:
Child DNA sample analysis
The child is homozygous for the sickle trait and suffers from sickle
cell anemia. Both genes have the mutation in the restriction enzyme
palindrome. Neither will be cut by the restriction enzyme and the pattern
will be a single DNA band on electrophoresis.
Lane 6:
Father DNA sample analysis
The father is heterozygous for the sickle trait. One of the pair of
genes (the normal gene) contains the restriction enzyme site. This gene
is cut by the restriction to produce two smaller pieces of DNA. The
second gene has a mutation within the palindrome. This change does not
allow the enzyme to cut the mutated gene into two smaller
Expected results
The picture below are the results of the class and are from RIGHT to
LEFT
