Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid?
A) succinate
B) malate
C) citrate
D) ?-ketoglutarate
E) isocitrate
Ans: D) ?-ketoglutarate
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Normal white blood cells (called B cells) and cancerous B cells that cause leukemia both carry a unique surface protein called CD-19
a. True b. False Indicate whether the statement is true or false
The brain almost exclusively uses blood glucose as its main energy source. This glucose comes from:
What will be an ideal response?
About what portion of all couples are affected by infertility?
A. Fewer than 1 percent B. About 3 percent C. About 8 percent D. About 13 percent E. Over 20 percent
Why is it important to compare DNA sequences in the construction of an evolutionary tree?
a. Similarities in physical appearance cannot be used to construct and evolutionary tree. b. Convergent evolution can cause distantly related organisms to appear closely related. DNA sequence analysis can show that they are actually distantly related. c. DNA sequence comparison is not required; homologous features alone are sufficient in evolutionary tree construction. d. RNA sequences are actually more important in constructing an evolutionary tree since they are the precursors to DNA. e. None of the above