Biolnteractive
Why Do Some People with the Sickle Cell Genotype Not have Symptoms?
PART 4: Transcribing and Translating
Below are parts of the DNA sequence for the HBB gene. There are two tables: one for the typical gene and one for the gene with the mutation that can lead to sickle cell disease. The sequences are broken into groups of three nucleotides each, called codons
For each table, you will transcribe the DNA into RNA. Then, you will translate the RNA into amino acids using the "Genetic Code Chart," which will be provided by your instructor.
13. Below the DNA sequence in Table 2, record the appropriate mRNA and amino acid sequences.
Table 2. Part of the typical HBB gene sequence.
Codon Number
1
2
3
4
5
6
7
DNA
MRNA
GUG
Amino acid
CAC
GTG
CBC.
GAC
CUG
TGA
GGA
CTT
CTC
val
His
Leu
ACU
Thr
Pro
GAA
GAG
GIU
Glu
14. Below the DNA fragment in Table 3, record the appropriate mRNA and amino acid sequences.
Table 3. Part of the HBB gene sequence with the mutation that can lead to sickle cell disease.
Codon Number
1
2
3
4
5
6
7
DNA
CAC
GTG
GAC
TGA
GGA
CAT
CTC
mRNA
GUG
CAC
CUG
ACU
CCU
GUA
GAG
Amino acid
Val
Pro His
Leu
Tur
Pro
Vai
15. Based on your results above:
a. Describe any differences between the "typical" and "sickle cell HBB gene sequences. Include the numbers of any affected codons.
Changed Only 1, CTT changed to CAT (codon 6).
b. is the mutation that occurred an addition, deletion, substitution, or inversion?
Substitution
c. How did the mutation impact the resulting amino acid sequence?
It changed it frown Glu to Val.