Ch. 21

How are DNADNA microarrays used? Select all that apply.

DNA microarrays can be used to identify pathogens. DNA microarrays are used to compare patterns of gene expression in tissues under different conditions. DNA microarrays are used to compare gene expression patterns in normal and diseased tissues.

Once the genome of a novel organism has been sequenced, how do you know the sequence is correct? Which of the following methods could be used to ensure that sequencing data is correct? Select all that apply.

Sequence the genome multiple times and compare the reads from each sequence. Sequence the complementary DNA strands at the same time and use base pairing to check the sequence.

Which approach was used for the Human Genome Project?

whole-genome sequencing (WGS)

What are DNA microarrays?

Most microarrays, or gene chips, consist of a glass slide that is coated with single-stranded DNADNA molecules. A single microarray can have 20,000 different spots of DNA, each containing a unique sequence.

What is the consensus sequence from Part B that has coverage included on at least 3 of the 5 DNA fragments (3x coverage)?

GGCCATC

Your research group has identified five SNPs in the insulin coding region. One of these SNPs was found in a patient with sporadic juvenile diabetes (patient 2), while others were found in four patients (1, 3, 4, and 5) who do not have diabetes. All of the individuals are heterozygous for a rare SNP variant and wild-type insulin. As a preliminary characterization of these SNPs, you perform an SDS PAGE/Western blot analysis of protein samples from each patient. Because SDS denatures proteins and breaks disulfide bonds, you prepare three blots and probe them separately with antibodies specific to the A chain, B chain, and C peptide. For each blot, you use a sample from a homozygous wild-type individual as a control. You obtain the following results: What can you conclude from these results? Select the true statement(s) from the list below.

In patients 1, 4, and 5, the fragment bound by the anti-A chain antibody is the same length as wild-type. In patient 2, a wild-type amount of protein is detected with the anti-B chain antibody. In patient 3, both anti-A chain and anti-B chain antibodies detect less protein than in wild-type.

Now that you have determined that the sequence in Part B is part of the human insulin gene, you can use BLAST to search the human-specific (Human genomic + transcript) database. This database lists genomic sequences separately from annotated mRNA transcripts. A new page displays your search results. Again, the Descriptions section of the page lists similar sequences, or hits, with the best statistical match to your query sequence at the top of the list. Note that in this case, transcripts (mRNA) and genomic sequences are listed separately. You should see several results but only human (Homo sapiens) sequences. If not, see Hint 1 to determine what went wrong. Based on these BLAST results, what can you conclude about your query sequence? Select all that apply.

The query coverage data indicate that part of the query sequence is not present in any mRNA transcript for insulin. The sequence is part of four distinct insulin mRNA transcripts.