MOD 1 UNIT 2: THE CELL (PART 3/CLINICAL CORRELATIONS)

Question 1

is a hereditary condition caused by abnormal carrier proteins that are
unable to remove cystine from the urine, resulting in the formation of kidney stones.

Answer 1

cystinuria

Question 2

TRUE OR FALSE

Autoimmune diseases may lead to the production of antibodies that specifically bind
to and activate certain plasma membrane receptors. An example is Graves disease
(hyperthyroidism).

Answer 2

TRUE

Question 3

is an exotoxin produced by the bacterium Vibrio cholerae that alters Gs
protein so that it is unable to hydrolyze its GTP molecule. As a result, cAMP levels increase in
the surface-absorptive cells of the intestine, leading to excessive loss of electrolytes and
water and severe diarrhea.

Answer 3

cholera toxin

Question 4

the product of the bacterium that causes whooping cough, inserts ADP-
ribose into the subunits of trimeric G proteins, causing the accumulation of the inactive form of G proteins resulting in irritation of the mucosa of the bronchial passages.

Answer 4

Pertussis toxin

Question 5

may lead to mental retardation, diminished growth and sexual development, and decreased responses to certain hormones.

Answer 5

Defective Gs proteins

Question 6

results from a defective spectrin that has a decreased ability to bind to band 4.1 protein. The disease is characterized by fragile, misshapen red blood cells, or spherocytes; destruction of these spherocytes in the spleen leads to anemia.

Answer 6

Hereditary spherocytosis

Question 7

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

During high-speed car accidents and often in shaken baby syndrome, the sudden
accelerating and decelerating forces applied to the brain cause shearing damage to
axons, especially at the interface between white matter and gray matter.

The stretching of
the axons result in diffuse axonal injury, a widespread lesion whose consequence is the
onset of a persistent coma from
which only 10% of the affected individuals regain consciousness.

Answer 7

“C”

Question 8

are the result of mutations of certain regulatory genes, called proto-
oncogenes, which normally stimulate or inhibit cell proliferation and development.

Answer 8

Oncogenes

Question 9

TRUE OR FALSE

Transformed cells have lost their ability to respond to regulatory signals controlling the
cell cycle, and by this, they may undergo cell division indefinitely, thus becoming
cancerous.

Answer 9

TRUE

Question 10

Sometimes the members of a pair fail to separate, resulting in one daughter cell
containing an extra chromosome (n 1 24), whereas the daughter cell at the opposite pole
is minus a chromosome (n 1 22). This development is known as

Answer 10

nondisjunction

Question 11

TRUE OR FALSE

Chromosomes 6, 8, 9, 13, 18, and 21 are those
chromosomes most frequently affected by nondisjunction.

Answer 11

FALSE

” 8, 9, 13, 18, and 21 “

Question 12

defined as an abnormal number of chromosomes, can be detected by
karyotyping.

Answer 12

Aneuploidy

Question 13

is characterized by mental retardation, short stature, stubby appendages, congenital heart malformations, and other defects.

Answer 13

Down syndrome (trisomy 21)

Question 14

is aneuploidy of the sex chromosomes, characterized by infertility, variable degrees of masculinization, and small testes.

Answer 14

Klinefelter syndrome (XXY)

Question 15

is monosomy of the sex chromosomes, characterized by short stature, sterility, and various other abnormalities.

Answer 15

Turner syndrome (XO)

Question 16

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

At the presynaptic nerve terminal, one of the t-SNARES is SNAP-25, a fusion protein.

Botox (botulinum neurotoxin A) cleaves SNAP-25 and prevents the synaptic vesicles from anchoring and releasing their neurotransmitter, thus preventing neuromuscular transmission and contraction. This leads to a flaccid paralysis of the postsynaptic muscle.

Answer 16

“C”

Question 17

is a genetic disease in which normal peroxisomes are absent. Infants
with this syndrome have profound neurological disorders and liver and kidney problems
and usually die within a few months. Electron micrographs of biopsies from these patients
reveal empty peroxisomes, lacking enzymes. Although peroxisomal enzymes may be
synthesized, they become dislocated in the cytosol.

Answer 17

Zellweger syndrome

Question 18

is caused by the inability of peroxisomes to metabolize fatty acids. Therefore, lipids accumulate in the nervous system and adrenal glands, impairing their function.

Answer 18

Adrenoleukodystrophy

Question 19

is often based on immunocytochemical identification of the intermediate filaments in the tumor cells because the type of intermediate filament present identifies the tissue from which the metastatic cancer cells originated.

Answer 19

tumor diagnosis

Question 20

is associated with a decreased ability of
cells to take in cholesterol, which normally is ingested by receptormediated
endocytosis of LDLs.

Answer 20

Familial hypercholesterolemia

Question 21

This disease is caused by an inherited genetic defect that results in an inability to
synthesize LDL receptors or in the synthesis of defective receptors unable to bind either to
LDLs or to clathrin-coated pits.

Answer 21

Familial hypercholesterolemia

Question 22

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

Anemia is characterized by an elevated level of cholesterol in the bloodstream.

This facilitates early development of atherosclerosis, which may be fatal.

Answer 22

“B”

first statement, “Familial hypercholesterolemia”

Question 23

TRUE OR FALSE

Lysosomal storage diseases are hereditary disorders caused by a deficiency in specific lysosomal acid hydrolases.

Answer 23

TRUE

Question 24

is characterized by glycolipids (namely, GM2 gangliosides) accumulating in the lysosomes of neurons as a result of a deficiency of the enzyme
hexosaminidase A. The disease is most common in children of central European Jewish
descent. The large buildup of gangliosides in neurons of the brain results in marked
degenerative changes in the central nervous system, and death usually occurs before the
age of 4 years.

Answer 24

Tay-Sachs disease

Question 25

This rare inherited disease is caused by a deficiency in any 1 of 10 lysosomal enzymes involved in the sequential degradation of GAGs. Clinical features of Hurler syndrome include skeletal deformities, enlarged organs, progressive mental deterioration, deafness, and death before the age of 10 years.

Answer 25

Hurler syndrome

Question 26

are caused by a hereditary defect in an enzyme involved in either the synthesis or the degradation of glycogen. As a result, glycogen accumulates most often in the liver, skeletal muscle, and the heart, but the major organ involvement depends on the particular enzymatic defect.

Answer 26

Glycogen storage diseases