L-lysine is an essential amino acid and must be supplied in the diet. By comparison, the stereoisomer D-lysine is not biologically active. Why can your body only utilize one form?
A. Since the L form and D form are enantiomers, they will bind together and inhibit utilization of the D form.
B. Since the L form and D form are chiral molecules, they will bind together and inhibit utilization of the D form.
C. Antibodies recognize the D form and destroy it before your body can use it for nutritional purposes.
D. Enzymes can only recognize a single, specific stereoisomer.
D
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Paramecium is a single-cell eukaryotic organism that can reproduce by mitotic cell division. Prior to the M phase of the cell cycle, which of the following must occur?
A. The cell must replicate its chromosomes. B. The cell must first be fertilized. C. The nucleus must divide. D. Chromatids must be separated. E. The nuclear envelope must disintegrate.
All of the following are critical factors for DNA replication on the leading strand EXCEPT?
A. primer B. DNA ligase C. DNA polymerase D. DNA primase E. deoxynucleoside triphosphates
How many quanta of light are needed to reduce one molecule of carbon dioxide to carbohydrate during photosynthesis?
A. 10-12 B. 2 C. 3 D. 4
In cats an X-linked pair of alleles, B and b, controls color of fur. The alleles are incompletely
dominant: B produces black, b produces yellow, and Bb produces tortoise-shell. (a) A yellow cat had a litter of two tortoiseshell kittens and one yellow. What is the sex of the yellow kitten? (b) A tortoiseshell cat brings home a litter of black, yellow, and tortoiseshell kittens. The color of which sex would tell you the color of the tomcat that produced them? (c) A yellow male is crossed with a tortoiseshell female. If the female has all male kittens in her litter of four, what color(s) would they be? (d) A tortoiseshell cat brings home her litter of black, yellow, and tortoiseshell kittens. By what method could you possibly decide whether the male parent was the black tomcat next door? What will be an ideal response?