Glycolysis is the first step in cellular respiration, and it is anaerobic. It occurs in the cytoplasm, so it not only happens in eukaryotic cells, but also in prokaryotic cells. This process when simplified, breaks one glucose molecule down into two pyruvate molecules, which is an exergonic process. The reactants for glycolysis are glucose, 2 NAD+, 2 ATP, 4 ADP, and 4 P(i). The products are 2 pyruvates, 2 NADH, 2 ADP and 4 ATP. The glucose molecule is oxidized to create the two pyruvate molecules. The two ATP molecules are considered investments, since there are four ATP molecules produced. There is a net increase of 2 ATP molecules, which are produced using substrate level phosphorylation. Substrate level phosphorylation uses a kinase enzyme to transfer a phosphate group from a substrate to an ADP molecule to make ATP.
The first step is using hexokinase to attach a phosphate group to the glucose, making the molecule a glucose 6-phosphate using one ATP molecule. This glucose 6-phosphate molecule is then changed to an isomer, which means the chemical formula is the same but the location and structure is changed, using a phosphoglucose isomerase to make a fructose 6-phosphate. The fructose 6-phosphate is synthesized using phosphofructokinase-1 and an ATP molecule to attach another phosphate group to make it fructose 1,6-bisphosphate. This is then separated into dihydroxyacetone phosphate to then become two glyceraldehyde 3-phosphate, or directly into two glyceraldehyde 3-phosphate. The glyceraldehyde 3-phosphate dehydrogenase uses 2 NAD+ and reduces it to 2 NADH molecules to take away hydrogen and add a phosphate instead to make two molecules of 1,3-bisphosphoglycerate. Phosphoglycerate kinase uses 2 ADP and attaches a phosphate that is taken from the two molecules of 1,3-bisphosphoglycerate to form two molecules of 3-phosphoglycerate. The phosphoglyceromutase synthesizes the two molecules of 3-phosphoglycerate into two molecules of 2-phosphoglycerate which is an isomer. Enolase takes 2H2O molecules and forms two molecules of phosphoenolpyruvate which has a 2,3 double carbon bond. Pyruvate kinase uses 2 ADP molecules to synthesize 2 molecules of pyruvate from the two molecules of phosphoenolpyruvate.
Krebs Cycle (Citric Acid Cycle)
In which molecules is most of the energy from the citric acid cycle’s redox reactions conserved? Where will these molecules go to next?
The molecules that conserve the most energy from the citric acid cycle are the NADH molecules. They are formed when the NAD+ molecules are reduced. These molecules are transported using the electron transport chain and become hydrogen donors. These hydrogens are saved to make ATP after being transported to the intermembrane of the mitochondria and through oxidative phosphorylation create ATP molecules from preexisting ADP molecules. The NADH molecule is able to produce 3 individual ATP molecules during oxidative phosphorylation.
What are the TOTAL products of the Krebs cycle?(ONE ROUND)
From one round of the Krebs cycle, 3 molecules of NADH and 1 molecule of FADH2 are generated along with 2 CO2 molecules and 1 ATP or GTP molecule. The molecule left over to repeat the process is 1 oxaloacetate.
How many NADH and FADH2 molecules are produced per one molecule of glucose in the Krebs cycle?
Per one molecule of glucose, the Krebs cycle is repeated twice. This means that 6 molecules of NADH and 2 molecules of FADH2 are generated along with 4 CO2 molecules and 2 ATP or GTP molecules. 2 oxaloacetate are left over to repeat the process.