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Fructose is a ketohexose monosaccharide found in honey, fruits, and other sources. It is also added to some foods and drinks as a sweetener. Much of the fructose taken in through digestion is taken up and processed by the liver, where it is phosphorylated and cleaved.
Which of the following statements accurately describe(s) how fructose metabolism in the liver differs from glucose metabolism? Select all that apply
1. In fructose metabolism, the phosphofructokinase reaction is bypassed, and glycolysis can proceed regardless of need.
2. The presence of fructose inhibits the entrance of glucose into glycolysis.
3. The major control point in both glucose and fructose metabolism is the reaction catalyzed by phosphofructokinase.
4. The fructose 1-phosphate pathway can deplete intracellular phosphate/ATP.

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The phosphofructokinase (PFK) reaction is bypassed in the presence of fructose hence 1 is correct and 3 is not. Fructose metabolism results in more metabolites undergoing glycolysis from glyceraldehyde onwards but does not inhibit hexokinase from metabolising glucose to glucose 6 phosphate hence entry of glucose into glycolysis is not inhibited, 2 is false. Fructose 1 phosphate pathway utilises 2 ATP and regenerates 2 ATP in the glycolytic pathways and hence there is no net ATP loss thus 4 is incorrect as well.