Page 70 - Genetics_From_Genes_to_Genomes_6th_FULL_Part3
P. 70
364 Chapter 10 Genome Annotation
significant is the match. For this exercise, look only at b. Are the mildly thalassemic individuals with Lepore
the first entry in the list, with the lowest E value. hemoglobin homozygotes or heterozygotes for the
a. What is the human gene that best matches the unusual allele?
query sequence? c. Why might these mildly thalassemic people pro-
Now migrate down on the same page to the list of duce less Lepore hemoglobin than normal adult
Alignments. Look only at the first entry, which cor- hemoglobin?
responds to the first entry under the Descriptions. 27. The α1 and α2 genes in humans are identical in their
b. Is the match exact or is it imperfect? coding regions. With this fact and your answer to Prob-
Go back to the nucleotide blast page. Using the same lem 26 in mind, describe a mechanism that might fre-
query sequence (from Fig. 9.7f), now choose “mouse quently produce a deletion of one of these two genes.
genomic + transcript” as the database to search. 28. The following figure shows an electrophoretic analy-
c. Is this gene conserved in the mouse? If so, how sis of the hemoglobin proteins present in normal
well conserved? adults, newborns, and fetuses. Each band represents a
complete hemoglobin protein with all of its subunits.
25. Use the UCSC Genome Browser (http://genome The intensity of the band indicates the relative
.ucsc.edu/cgi-bin/hgGateway) to identify the two amount of that protein in the sample.
major genes illustrated in the figure accompanying
Problem 10.14.
X
Section 10.4
26. Certain individuals with mild forms of
β-thalassemia produce, in addition to normal adult Y
hemoglobin with two α chains and two β chains,
lower levels of an unusual, so-called Lepore
hemoglobin with two α chains and two chains in Z
each of which the N-terminal half comes from a
normal δ chain and the C-terminal half comes Adult Newborn Fetus
from a normal β chain. Certain other individuals a. What is the subunit structure of the hemoglobin
who are asymptomatic produce a different, unusual molecules marked X, Y, and Z?
anti-Lepore hemoglobin that contains two α chains
and two chains in which the N-terminal half comes b. Name one abnormal condition that should
from a normal β chain and the C-terminal half increase the percentage of hemoglobin in a
comes from a normal δ chain. newborn that is HbZ.
a. Describe an event that could give rise to both c. Name one abnormal condition that should increase
Lepore and anti-Lepore hemoglobins. the percentage of hemoglobin in an adult that is HbY.
