Mastering Biology: Chapter 21

What is the percent identity between the β and ε globin sequences?

76%

Notice that the cells in the lower left half of the table are blank. Why?

They represent duplicates of the comparisons in the upper right half of the table.

Which type of chromosomal rearrangement accounts for the creation of the gene that encodes the BCR-ABL chimeric protein?

translocation

In how many positions are there nucleotide differences between your query sequence and the sequence of accession AY259214.1?

10

What percent identity is implied by the dashes?

100% identity

On which chromosome is the BCR gene normally located?

22

Which of the following percent identities is a good cut-off value separating within-family pairings from between-family pairings?

50%

Which segment of the normal ABL protein aligns with the query sequence?

80,246

Which statement best describes the results shown in the Descriptions section?

A hit derived from Fusarium redolens is the best match to the query sequence.

In which section of the search results can you find nucleotide-by-nucleotide comparisons between your query sequence and similar database sequences?

Alignments

How do the E values change as you go from the top of the list of hits to the bottom?

E values get larger

Select the correct statement about genome size and density.

Eukaryotic genomes are larger than prokaryotic genomes.

How does the alignment of the FN397219.1 sequence to your query sequence compare to the alignment of the AY259214.1 sequence you examined in Part F?

In the FN397219.1 alignment, there are the same number of nucleotide differences but more gaps.

How has gene duplication played a critical role in evolution?

It produces redundant copies of existing genes, which are then free to mutate and adopt new functions.

Based on the information given in the three different sections, which of the following statement(s) correctly describe(s) the hit that is most similar to the query sequence? Select all that apply.

Its accession number is CAM33009.1. It is a chimeric protein. It is identical to the query sequence in length and amino acid sequence.

Which of the findings of the Human Genome Project were contrary to initial expectations?

Ninety-three percent of multi-exon human genes have alternatively spliced forms. The human genome contains fewer than 21,000 genes.

Several of the different globin genes are expressed in humans, but at different times in development. What is the most plausible mechanism for this?

Signal molecules forming specific transcription factors result in differential gene expression.

Did you find any sequences in the human genome that were statistically similar to your query sequence?

Similar sequences were found only with the blastn (lower similarity) search.

What is the most likely explanation?

The common ancestor of humans and chimps had 48 chromosomes and at some point a fusion event occurred and provided some selective advantage.

If a known gene functions as a tumor suppressor, predict which of the following pieces of evidence would be most useful in diagnosis of a cancer due to a mutation in this tumor-suppressor gene.

The mRNAs for the targeted tumor suppressor sequence are not being produced.

Which of the following conclusions has led to the comparison between the number of human genes and those of other animal species?

The number of proteins expressed by the human genome is far greater than the number of its genes.

Why is it more difficult to identify eukaryotic genes than prokaryotic genes using genomic techniques?

There are introns in eukaryotic genes.

Other than the genus and species information, what characteristics do most of the top hit sequences share?

They contain a ribosomal RNA (rRNA) sequence. They contain a sequence of an internal transcribed spacer (ITS).

By what mechanism might transposons contribute to gene duplication?

Transposons may promote unequal crossing over during meiosis.

Does the order of pairs in the table above describe the same relative "closeness" of globin family members as shown in the model?

Yes. Pairs of globins at the top of the table are drawn with the closest connections in the model.

A recent study compared the Homo sapiens genome with that of Neanderthals. The results of the study indicated that there was a mixing of the two genomes at some period in evolutionary history. Which of the following potential discoveries of additional data might be consistent with this hypothesis?

a few modern H. sapiens with some Neanderthal sequences

Examine the descriptions for the group of hits that align with the N-terminal end of the query sequence. Which of the following terms are found among these descriptions?

breakpoint cluster region protein unnamed protein product BCR variant protein

Biologists now routinely test for homology between genes in different species. If genes are determined to be homologous, how are they related to each other?

by descent from a common ancestor

BLAST is a computational tool used by genome biologists to

compare a given DNA or protein sequence to all other DNA or protein sequences in a database

Two eukaryotic proteins have one domain in common but are otherwise very different. Which of the following processes is most likely to have contributed to this similarity?

exon shuffling

Which kingdom does Fusarium redolens belong to?

fungi

After finding a new medicinal plant, a pharmaceutical company decides to determine if the plant has genes similar to those of other known medicinal plants. What would annotation of the genome of this plant allow the company to determine?

identify genes and determine their functions

During which of the following processes does exon shuffling occur?

meiotic recombination

A current view of how the human and chimpanzee can share most of their nucleotide sequences yet exhibit significant phenotypic differences is that many of the most important sequence differences alter

regulatory sequences

Identify the three main categories of hits in terms of similarity to the query sequence.

sequences that are similar to the first 75 amino acids of the query sequence sequences that are similar to the last 170 amino acids of the query sequence sequences that are similar to the entire length of the query sequence

Fragments of DNA have been extracted from the remnants of extinct woolly mammoths, amplified, and sequenced. How can these fragments of DNA now be used?

to better understand the evolutionary relationships among members of related taxa

What type of noncoding DNA comprises the largest portion of multicellular eukaryotic genomes?

transposons

Based on that premise, identify which two globin genes are the most recently duplicated. What is the percent amino acid identity between them?

α1 and α2 , with 100% amino acid identity

Which two globin genes are most divergent from each other? What is the percent amino acid identity between them?

β and ζ, with 38% amino acid identity