Once an organism's genome sequence has been determined, how do scientists generally start identifying all the genes within the genome?

• A. Hybridize the DNA with probes specific for known genes from other organisms.
• B. Use DNA microarrays to examine the expression of huge numbers of sequences from the genome under different conditions.
• C. Individually mutate all of the nucleotides within the genome, and determine which mutations cause a detectable phenotype.
• D. None of the listed responses is correct.
• E. Analyze the sequence using software that scans the sequence for telltale sequence elements such as promoters, transcription start and stop sites, and so on.

Answer: (E)

Verified step by step guidance

1. Start by understanding that once a genome is sequenced, the raw data consists of a long string of nucleotides (A, T, C, G). This sequence needs to be analyzed to identify genes.
2. Recognize that genes have specific features such as promoters, transcription start sites, and stop codons. These features can be identified using bioinformatics tools.
3. Use software that scans the genome sequence for these telltale sequence elements. This software uses algorithms to predict where genes are likely to be located based on known patterns.
4. The software will look for open reading frames (ORFs), which are sequences of DNA that could potentially code for proteins. ORFs are identified by looking for start codons (like ATG) and stop codons (like TAA, TAG, TGA) in the sequence.
5. Finally, the software may also compare the genome sequence to databases of known genes from other organisms to find similarities, which can help in identifying genes that have been conserved through evolution.