E. Termination of translation is independent of guanosine triphosphate hydrolysis.
F. The Shine-Dalgarno sequence facilitates the binding of the large ribosomal subunit to eukaryotic messenger RNA (mRNA).
Q2. The Centers for Disease Control and Prevention recommends a two-tier testing procedure for Lyme disease that involves a screening enzyme-linked immunosorbent assay (ELISA) followed by a confirmatory western blot analysis on any sample with a positive or equivocal ELISA result. Which of the following statements about these testing procedures is correct?
A. Both techniques are used to detect specific mRNA.
B. Both techniques involve the use of antibodies.
C. ELISA requires the use of electrophoresis.
D. Western blots require use of the polymerase chain reaction. Q3. Why are eukaryotic cells unaffected by antibiotics in the tetracycline class?
Case 3: Blood on the Toothbrush
Patient Presentation: LT is an 84-year-old man whose gums have been bleeding for several months.
Focused History: LT is a widower and lives alone in a suburban community on the East Coast. He no longer drives. His two children live on the West Coast and come east infrequently. Since the death of his wife 11 months ago, he has been isolated and finds it hard to get out of the house. His appetite has changed, and he is content with cereal, coffee, and packaged snacks. Chewing is difficult.
Pertinent Findings: The physical examination was remarkable for the presence of swollen dark-colored gums (see image at right). Several of LT’s teeth were loose, including one that anchors his dental bridge. Several black and blue marks (ecchymoses) were noted on the legs, and an unhealed sore was present on the right wrist. Inspection of his scalp revealed tiny red spots (petechiae) around some of the hair follicles. Blood was drawn for testing.
Results of tests on LT’s blood:
The test for blood in his stool (occult blood test) was negative.
Results of follow-up tests (obtained several days after the appointment) included the following:
H = High; L = Low.
Diagnosis: LT has vitamin C deficiency with a microcytic, hypochromic anemia secondary to the deficiency.
Treatment: LT was prescribed vitamin C (as oral ascorbic acid) and iron (as oral ferrous sulfate) supplements. He will also be referred to social services.
Prognosis: The prognosis for recovery is excellent.
Case-Related Questions: Choose the ONE best answer.
Q1. Which of the following statements about vitamin C is correct? Vitamin C is:
A. a competitor of iron absorption in the intestine.
B. a fat-soluble vitamin with a 3-month supply typically stored in adipose tissue.
C. a coenzyme in several enzymic reactions such as the hydroxylation of proline.
D. required for the cross-linking of collagen.
Q2. In contrast to the microcytic anemia characteristic of iron deficiency (common in older adults), a macrocytic anemia is seen with deficiencies of vitamin B12 and/or folic acid. These vitamin deficiencies are also common in older adults. Which of the following statements concerning these vitamins is correct?
A. An inability to absorb B12 results in pernicious anemia.
B. Both vitamins cause changes in gene expression.
C. Folic acid plays a key role in energy metabolism in most cells.
D. Treatment with methotrexate can result in toxic levels of the coenzyme form of folic acid.
E. Vitamin B12 is the coenzyme for enzymes catalyzing amino acid deaminations, decarboxylations, and transaminations. Q3. How do hemolytic anemias differ from nutritional anemias?
Case 4: Rapid Heart Rate, Headache, and Sweating