![]() In the second step of glycolysis, an isomerase converts glucose-6-phosphate into one of its isomers, fructose-6-phosphate (this isomer has a phosphate attached at the location of the sixth carbon of the ring). ![]() This reaction prevents the phosphorylated glucose molecule from continuing to interact with the GLUT proteins, and it can no longer leave the cell because the negatively charged phosphate will not allow it to cross the hydrophobic interior of the plasma membrane. Hexokinase phosphorylates glucose using ATP as the source of the phosphate, producing glucose-6-phosphate, a more reactive form of glucose. The first step in glycolysis (Figure 7.8) is catalyzed by hexokinase, an enzyme with broad specificity that catalyzes the phosphorylation of six-carbon sugars. The second part of glycolysis extracts energy from the molecules and stores it in the form of ATP and NADH-remember: this is the reduced form of NAD.įirst Half of Glycolysis (Energy-Requiring Steps) The first part of the glycolysis pathway traps the glucose molecule in the cell and uses energy to modify it so that the six-carbon sugar molecule can be split evenly into the two three-carbon molecules. Glycolysis consists of two distinct phases. Glycolysis begins with the six-carbon ring-shaped structure of a single glucose molecule and ends with two molecules of a three-carbon sugar called pyruvate. These transporters assist in the facilitated diffusion of glucose. The other mechanism uses a group of integral proteins called GLUT proteins, also known as glucose transporter proteins. One method is through secondary active transport in which the transport takes place against the glucose concentration gradient. Glucose enters heterotrophic cells in two ways. Glycolysis takes place in the cytoplasm of both prokaryotic and eukaryotic cells. The process does not use oxygen directly and therefore is termed anaerobic. In fact, nearly all living organisms carry out glycolysis as part of their metabolism. Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism. Compare the output of glycolysis in terms of ATP molecules and NADH molecules producedĪs you have read, nearly all of the energy used by living cells comes to them in the bonds of the sugar glucose.Describe the overall result in terms of molecules produced during the chemical breakdown of glucose by glycolysis.\)īy the end of this section, you will be able to do the following:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |