An individual heterozygous for sickle-cell disease produces both normal and abnormal polypeptides. This is an
example of ____.
a. epistasis
b. incomplete dominance
c. polygenic inheritance
d. multiple alleles
e. pleiotropy
ANSWER: b
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Amino acid variability is especially apparent in several ________ in the V domains of different immunoglobulins
A) heavy chains B) complementarity-determining regions (CDR) C) peptide motifs D) epitopes
Unlike white blood cells, red blood cells lose their ________ and ________ as they mature
A) nucleus; organelles B) nucleus; ATP C) organelles; plasma membrane D) nucleolus; cytoplasm E) flexibility; shape
The natural role of restriction enzymes in bacteria is to
A) make conjugation more efficient. B) allow transposons to move to another place in the chromosome. C) protect the cell from invading phages. D) allow cells to accept foreign DNA. E) provide the cell with new phenotypes, such as antibiotic resistance.
Please match the virulence factor of Streptococcus pyogenes to its description.
Hyaluronidase A) Surface antigen that serves as the basis for alphabetical grouping; protects bacterium from lysozyme B) Toxin that causes beta-hemolysis on blood agar and injures cells of the host C) Enzyme that plays a role in invasion by leading to the digestion of fibrin clots D) Projecting surface antigen that facilitates adherence and resists phagocytosis E) Chemical surface layer that prevents an immune response by the host F) Enzyme that promotes invasion into tissues by breaking down the binding substance in connective tissues