Tutor profile: Stacy Lisa T.
Which of the following increases with increasing atomic number within a family on the periodic table? A. electronegativity B. electron affinity C. atomic radius D. ionization energy
Correct Answer = C. A family or group is the name of any vertical column on the periodic table. Of the choices given only the atomic radius increases going down a column. Although electron affinity is a possible choice depending upon the definition used, atomic radius is an unambiguous choice.
A 78-year old man is diagnosed with scuvry, which is caused by a defect in the collagen protein. His defective collagen results from.... A. genetic defect from unstable collagen triple helices B. inability to hydroxylate proline and lysine residues C. Inability to cross-link lysine residues D. a mutation that replaces a glycine residue for a larger acidic amino acid E. Vitamin C medicated destruction of tropocollagen molecules
Correct Answer= B, Scurvy is not a genetic disease, but an acquired deficiency of Vitamin C. Vitamin C is vital in the hydroxylation process of lysine and proline residues on the collagen proteins. Some proteins require additional structural modification to carry out the functions. Without proper Vitamin C nutrition, the hydroxylation process will not occur causing the creation of a defective collagen protein.
A glycoprotein on the surface of a cell is the ligand of a particular adhesion molecule. Therefore, that adhesion molecule most likely belongs to which family? A. Cadherins B. Collagens C. Immunoglobulin superfamily D. Intergrins E. Selectins
Correct Answer = E. Selectins are adhesion molecules that bind to carbohydrates-containing ligands which is asked for in the question above. Cadherins bind to other cadherins and not to carbohydrates. Immunoglobulin members often have intergrins as ligands. Intergrins mediate cell to extracellular matrix interactions (fibrous proteins), not cell to carbohydrate interactions. And Collagen are fibrous proteins of the extracellular matrix and not a part of the adhesion molecule category.
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