937
CHAPTER TWENTY-FOUR
Genetics and Genomics
19
Distinguish between a sex-limited and a sex-inf
uenced
trait. (p. 928)
20
DeF
ne
genomic imprinting.
(p. 929)
24.6 Chromosome Disorders
21
State whether trisomy 21 Down syndrome is euploid,
aneuploid, or polyploid. (p. 929)
22
In nondisjunction ______________. (p. 929)
a. multiple sets o± chromosomes are inherited
b. gametes (sperm and eggs) receive only even-
numbered chromosomes or only odd-numbered
chromosomes
c. a chromosome pair ±ails to separate during meiosis,
and as a result a gamete has an extra or missing
chromosome
d. two eggs ±ertilize each other
23
Describe three types o± prenatal tests. (p. 931)
24.7 Gene Expression Explains Aspects of Anatomy and
Physiology
24
Explain how gene expression proF
ling can add to our
knowledge o± anatomy and physiology. (p. 933)
25
Explain how gene expression proF
ling di²
ers ±rom
studying mutations in a single gene. (p. 933)
26
List the steps in using gene expression proF
ling to
compare the proteins in a skin cell ±rom an oily part o± a
±ace to a cell ±rom a dry part o± the same ±ace. (p. 933)
27
Explain how gene expression proF
ling can improve the
cacy o± drugs to treat cancer. (p. 934)
24.3 Factors That A±
ect Expression of Single Genes
9
Explain the distinction between penetrance and
expressivity. (p. 924)
10
A single gene disorder that produces several symptoms is
______________. (p. 924)
11
A single syndrome that can have more than one genetic
cause exhibits ______________. (p. 924)
a. pleiotropy
b. incomplete penetrance
c. genetic heterogeneity
d. variable expressivity
24.4 Multifactorial Traits
12
DeF
ne
multifactorial trait.
(p. 924)
13
List three multi±actorial traits. (p. 924)
14
Explain why the ±requency distributions o± di²
erent
multi±actorial traits give very similar bell curves. (p. 926)
15
Give an example o± how the environment can inf
uence a
multi±actorial trait. (p. 926)
24.5 Matters of Sex
16
Explain how genes and chromosomes determine sex.
(p. 927)
17
Explain why Y-linked traits are passed only ±rom ±athers to
sons. (p. 928)
18
Explain why the inheritance pattern o± X-linked traits
di²
ers in males and ±emales. (p. 928)
OUTCOMES 4.7, 24.1, 24.2
1. Bob and Joan know from a blood test that they are each
heterozygous (carriers) for the autosomal recessive gene
that causes sickle cell disease. If their F
rst three children are
healthy, what is the probability that their fourth child will have
the disease?
OUTCOMES 6.2, 24.4
2. Why are medium-brown skin colors more common than very
white or very black skin?
OUTCOMES 6.3, 24.2, 24.3
3. A balding man undergoes a treatment that transfers some of
the hair from the sides of his head, where it is still plentiful, to
the top. Is he altering his phenotype or his genotype?
OUTCOMES 24.1, 24.2
4. A young couple is devastated when their second child is born
and has C±. Their older child is healthy, and no one else in the
family has C±. How is this possible?
INTEGRATIVE ASSESSMENTS/CRITICAL THINKING
OUTCOMES 24.1, 24.2, 24.3
5. C± is an autosomal recessive disorder that varies widely in
phenotype, from great difF
culty in breathing and digesting, to
frequent bouts of sinusitis, bronchitis, and/or pneumonia. In
the Maxwell family, the mother, Matilida, has a mild case—she
often suffers from respiratory infections. Her husband Jake
is a heterozygote, and testing reveals that he carries an allele
associated with severe disease. Of the four Maxwell children,
Katie and Jim have fairly severe disease, although Jim has to
be hospitalized more frequently than Katie. The other two
children, Emily and Rose, do not have C±.
a. Explain how Katie and Jim can have severe cases of C±
when one parent does not have the disease and the other
has a mild case.
b. Explain how Katie and Jim have different severities of the
illness.
c. What is the probability that Emily or Rose is a carrier, like
their father?
OUTCOMES 24.4, 24.7
6. A DNA microarray can predict which individuals who smoke
cigarettes are at increased risk of developing lung cancer.
Explain how making such a prediction entails genetics and
environmental infl
uences.
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