Relapsing fever is characterized by recurring episodes of fever and septicemia separated by symptom-free intervals. What causes this pattern?
What will be an ideal response?
Relapsing fever is caused by Borrelia recurrentis and other Borrelia species. This bacterium continually changes its antigenic surface components throughout its life cycle in its human host. Because the body's defense is to create antibodies directed against these surface molecules, some bacteria with surface antigens different from the antigens being targeted by the immune response manage to evade the immune system. These surviving spirochetes go on to multiply and cause a relapse of the fever. This cycle continues, with a few changed spirochetes evading the system each time and causing the next round of the disease.
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Which of the following is not true of the enzyme-substrate interaction?
A) Many enzymes are extremely specific regarding a substrate. B) Many enzymes cannot recognize a stereoisomer of their substrate. C) Some enzymes accept any of a whole group of substrates. D) Carboxypeptidase recognizes any of the amino acids from the carboxyl end of a polypeptide. E) Cells are often able to carry out metabolic activity with only a handful of enzymes.
Choose the letter that best describes the function of this receptor type: Meissner's corpuscle
A. tonic receptors located near the surface of the skin B. pressure sensitive receptors deep in the subcutaneous layer C. receptors on the face and fingertips sensitive to light touch
Some liverworts reproduce asexually by forming tiny balls of tissue called:a
setae. b. fronds. c. gemmae. d. prothalli. e. archegonia.
You are given the chemical code of one-half of a DNA double helix: CATGATTACCTAGAATCCTGTAAT. Which of the following sequences represents the codons and anticodons that would be used in creating a protein if the other half of the DNA strand is the coding strand?
A. mRNA codons: CATGATTACCTAGAATCCTGTAAT tRNA anticodons: CATGATTACCTAGAATCCTGTAAT B. mRNA codons: CAUGAUUACCUAGAAUCCUGUAAU tRNA anticodons: GUACUAAUGGAUCUUAGGACAUUA C. mRNA codons: CATGATTACCTAGAATCCTGTAAT tRNA anticodons: CAUGAUUACCUAGAAUCCUGUAAU D. mRNA codons: GUACUAAUGGAUCUUAGGACAUUA tRNA anticodons: CAUGAUUACCUAGAAUCCUGUAAU