Download Chapter 21 The human genome appears to have only about as

Chapter 21
1. The human genome appears to have only about as many genes as the simple nematode worm,
C. elegans. Which of the following best explains how the more complex humans can have
relatively few genes?
a. Human genes have unusually long introns involved in the regulation of gene expression.
b. More than one polypeptide can be produced from a gene by alternative splicing.
c. The human genome has a high proportion of noncoding DNA.
d. The human genome has a large number of SNPs (single nucleotide polymorphisms),
which increases genetic variability.
2. The human globin genes are located on two different chromosomes and include variants that
are expressed at different times in the life cycle as well as a number of nonfunctional
pseudogenes. Which of the following would best describe this gene family?
a. All the functional genes in the family have the same transcription control elements.
b. This gene family would be equivalent to the operons of prokaryotes.
c. Mutations in the hemoglobin gene led to its translocation to two different
chromosomes.
d. Identical or similar genes have evolved by gene duplication.
3. In 2005, Icelandic scientists reported finding a large chromosomal inversion present in 20% of
northern Europeans, and they noted that Icelandic women with this inversion had significantly
more children than women without it. What would you expect to happen to the frequency of
this inversion in the Icelandic population in future generations?