Name:__________________________________ Per._____ Date___________________
Mutated Hemoglobin Protein Synthesis Quiz (16 pts)
Background:
The condition known as Sickle Cell Anemia is believed to be the result of a mutation. People afflicted with
the disease have red blood cells that may be shaped like sickles, or crescents, under certain conditions.
Sickled red blood cells cannot carry the normal supply of oxygen. The odd shape of sickled cells also cause
them to clog tiny blood vessels in the body.
Hemoglobin is important in the normal transport of oxygen throughout the body in healthy individuals.
Sickle Cell Anemia is caused by an unusual form of hemoglobin, the molecule that carries oxygen in the
blood. Researchers have found that this unusual hemoglobin differs by only one amino acid from normal
hemoglobin. Instead of glutamic acid, the abnormal hemoglobin has valine in one of its polypeptide chains.
Scientists assume this is because one base triplet in the DNA molecule was changed, or mutated. Changes in
a single segment of a DNA or an RNA molecule are called point mutations.
Problem:
On the next page, there is a DNA sequence which codes for a small section of the protein hemoglobin. The
substitution of one amino acid in the long hemoglobin chain is believed to be responsible for this usually
fatal condition. Your mission is to determine which hemoglobin on the next page, #1 or #2 is mutated,
where on the chain this mistake has occurred and suggest the cause of the mutation. For Hemoglobin #1
and #2 on the next page, fill-in the table by converting the DNA to mRNA, to tRNA, and finally to amino
acids in order to find where the mistake has occurred. Use the mRNA decoding chart below to determine
the amino acids. You will then need to write under Hemoglobin #1 and #2 at the top whether that
hemoglobin is normal or mutated and then answer the follow-up questions under the table.
BE CAREFUL TO ONLY
USE mRNA TO FIGURE
OUT AMINO ACIDS
WHEN USING THIS
CHART
Hemoglobin #1____________________(+1 pt)
Hemoglobin #_____________________(+1 pt)
Write Normal or Mutated Above
Write Normal or Mutated Above
BE CAREFUL TO ONLY USE mRNA WITH DECODING CHART ON PREVIOUS PAGE
DNA
T
A
C
C
A
A
G
T
G
G
A
T
T
G
A
G
G
T
C
A
T
C
T
T
T
T
C
A
T
T
mRNA (+1)
tRNA (+1)
Amino Acid (+2)
DNA
T
A
C
C
A
A
G
T
G
G
A
T
T
G
A
G
G
T
C
T
T
C
T
C
T
T
T
A
T
C
mRNA (+1)
tRNA (+1)
Amino Acid (+2)
1) Which is the one amino acid in error above that is the cause of sickle cell anemia? (+2 pts)
_________________________
2) If we had the ability to fix the DNA above that is the source of the error that causes this wrong amino
acid, what is the nitrogen base letter that is in error and what should it be changed to? (+2 pts)
__________________________
3) Comparing Hemoglobin #1 to #2 above, you will find two of the same amino acids found in both that
are produced from DNA triplets that differ by one base letter. Which are the two amino acids? (+2 p)
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