104
U N I T 1
Cell and Tissue Function
R E V I EW E X E R C I S E S
1.
The Human Genome Project has revealed that
humans have only approximately 21,000 genes.
Only about 2% of the genome encodes instructions
for protein synthesis, whereas 50% consist of
repeat sequences that do not code proteins.
A.
Use this information to explain how this small
number of protein-encoding genes is able to
produce the vast array of proteins needed
for organ and structural development in the
embryo, as well as those needed for normal
function of the body in postnatal life.
2.
A child about to undergo surgery is typed for
possible blood transfusions. His parents are told
that he is type O positive. Both his mother and
father are type A positive.
A.
How would you go about explaining this
variation in blood type to the parents?
3.
The posttranslational folding of proteins is essential
to their proper functioning and degradation.
A.
Hypothesize on how age-related changes in the
folding of proteins in the central nervous system
could contribute to the development of the
neurofibrillary tangles that are characteristic of
Alzheimer disease.
4.
More than 100,000 people die of adverse drug
reactions each year; another 2.2 million experience
serious reactions; whereas others fail to respond at
all to the therapeutic actions of drugs.
A.
Explain how the use of information about
single-nucleotide polymorphisms
might be
used to map individual variations in drug
responses.
and reproduced many times over. As a result,
proteins that formerly were available only in
small amounts (e.g., human insulin) can now be
made in large quantities once their respective
genes have been isolated. Deoxyribonucleic acid
fingerprinting, which relies on recombinant DNA
technologies and those of genetic mapping, is
often used in forensic investigations.
■■
A newer strategy for management of genetic
disorders focuses on gene silencing by using
ribonucleic acid interference (RNAi) technology
to stop genes from making unwanted disease
proteins.
SUMMARY CONCEPTS
(continued)
5.
Human insulin, prepared by recombinant DNA
technology, is now available for the treatment of
diabetes mellitus.
A.
Explain the techniques used for the production
of a human hormone using this technology.
6.
Cystic fibrosis is a disorder of the cell membrane
chloride channel that causes the exocrine glands
of the body to produce abnormally thick mucus
resulting in the development of chronic obstructive
lung disease, pancreatitis, and infertility in men.
A.
Explain how a single mutant gene can produce
such devastating effects.
B.
The disease is transmitted as a single-gene
recessive trait. Describe the inheritance of the
disorder using Figure 5-11.
7.
Adult polycystic kidney disease is transmitted as an
autosomal dominant trait.
A.
Explain the parent-to-child transmission of this
disorder.
B.
Although the disease is transmitted as an
autosomal dominant trait, some people who
inherit the gene may develop symptoms early
in life, others may develop them later in life,
and still others may never develop significant
symptoms of the disease. Explain.
B I B L I O G R A P H Y
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