Untitled Quiz

Cellular Respiration

• Cellular respiration is the process by which cells break down glucose to release energy in the form of ATP.
• There are three main stages: glycolysis, the Krebs cycle, and oxidative phosphorylation.

Glycolysis

• Glycolysis occurs in the cytoplasm of the cell.
• During glycolysis, a six-carbon glucose molecule is broken down into two three-carbon pyruvate molecules.
• This process results in a net production of two ATP molecules per glucose molecule.
• Glycolysis does not require oxygen, so it can occur in both aerobic and anaerobic conditions.
• The enzyme hexokinase catalyzes the phosphorylation of glucose to glucose-6-phosphate in the first step of glycolysis.
• When NAD+ accepts hydrogen ions and electrons, it becomes NADH.
• The enzyme phosphoglucose isomerase converts glucose-6-phosphate into fructose-6-phosphate.
• When ATP levels are high, glycolysis is inhibited through feedback inhibition. This is a type of allosteric regulation that prevents the cell from producing excess ATP and conserves resources.
• The first half of glycolysis requires an investment of two ATP molecules to activate the glucose molecule and prepare it for cleavage. This is a key point to remember because it emphasizes that glycolysis itself involves energy investment before energy can be produced.
• The final products of glycolysis are two pyruvate molecules, two ATP molecules, and two NADH molecules.