Gluconeogenesis shares some, but not all, enzymes with the glycolytic pathway. It would appear to be more efficient if both pathways used all of the same enzymes since the pathways are essentially the reverses of each other. Why don't both pathways use all of the same enzymes?
A) The reactions where enzymes differ occur in different parts of the cell for glycolysis versus gluconeogenesis.
B) Enzymes can catalyze a reaction only in one direction, so naturally the two pathways have some enzymes that differ.
C) In tissues where gluconeogenesis occurs, the glycolytic enzymes are present at extremely low concentrations.
D) Three of the reaction steps in gluconeogenesis would have prohibitively large, positive free energies if they used glycolytic enzymes for their catalysis.

1. this system transports blood through the body and heart. 2. this system relates to the process by which an organism gets rid of its waste. 3.this system is responsible for movement of bones and fluids throughout the body. 4. this system receives and transmits information and responses. it depends upon electrical impulses created by the movement of charged particles. 5. this system relates to the process by which an organism replicates. sexually reproduction usually involves male cells (sperm) meeting female cells (eggs) to produce a fertilized egg or zygote. 6. this system gets oxygen to the cells of the body and rids the body of waste gases. some organisms use their skin. this is also a cell-level process. 7. this system relates to the structure and support of an organism. it is made of salts and proteins and found in vertebrate animals. 8. this is the system of organs which circulate blood around the body of most animals. 9. this system controls the glands that secrete hormones. 10. this organ system to protect the body from damage. itembank : system circulatory digestive system endocrine system excretory integumentary system muscular system nervous system reproductive system respiratory system skeletal system cardiovascular system