You perform Sanger sequencing on a small fragment of the human genome and obtain the following small sequence read: 5' AGGCTTAAGCTTAATCGGGCTAT 3'. In order to determine if this sequence might be within the coding region of a gene, you examine it for open reading frames. How many open reading frames exist that go all the way through this DNA fragment? (Recall that the stop codons are 5' TAA, 5' TAG, and 5' TGA.)

Explanation:

Dna sequence : 5' AGGCTTAAGCTTAATCGGGCTAT3'

mRna is complementary to the DNA strand ( template strand)

mRNA synthesis occur in 5'-3' direction.

mRNA sequence :

5' UCCGAAUUCGAAUUAGCCCGAUA3'

READING FRAMES :

5' UC CGA AUU CGA AUU AGC CCG AUA 3'

5' U CCG AAU UCG AAU UAG CCC GAU A 3' ( contain one stop codon).

5' UCC GAA UUC GAA UUA GCC CGA UA 3'

Total there are 2 reading frame.

Open reading frame are those which does not contain stop codon that is why they are called open.