Practice Performance Task: Thalassemia
Similar to sickle cell anemia, thalassemia (thal-uh-see-mee-uh) is an inherited
autosomal recessive blood disorder that affects the body's ability to produce functional
hemoglobin. Hemoglobin is a protein in red blood cells that is responsible for carrying
oxygen throughout the body. Thalassemia results from a mutation in the HBB gene,
which codes for a subunit of hemoglobin called beta-globin (ß-globin). The mutation
causes changes to the structure of ß-globin that decrease hemoglobin's ability to
carry oxygen. Low levels of oxygen in the bloodstream can lead to a variety of health
problems.
1. Two partial DNA sequences are provided below-one from a typical HBB gene
and one from a thalassemia HBB gene. An amino acid chart is also provided at the
top of the next page. Use this information to do the following:
(a) Transcribe each partial DNA sequence into mRNA.
(b) Use the amino acid chart to translate each mRNA sequence into the
appropriate amino acid sequence. (You may use abbreviations.)
Typical HBB Gene
Partial DNA sequence ACCTGGGTC
mRNA sequence
Amino acid sequence
Thalassemia HBB Gene
Partial DNA sequence
ACCTGGATC
mRNA sequence
Amino acid sequence