Glycolysis WALT Glycolysis takes part in the cytosol of the cell Glucose is oxidised to pyruvate by a series of reactions It produces a net of 2 ATP per molecule of glucose and 2 NADH

Glycolysis Glycolysis is a series of biochemical reactions by which a molecule of glucose is oxidised to two molecules of pyruvic acid. Glycolysis serves two principal functions: generation of high-energy molecules (ATP and NADH), and production of a variety of six- or three-carbon intermediate metabolites. Glycolysis is one of the most universal metabolic processes known, and occurs (with variations) in many types of cells in nearly all types of organisms.

NAD and FAD A couple of other molecules are important as electron-carrying molecules. Nicotinamide Adenine Dinucleotide (NAD) a coenzyme derived from the vitamin niacin, or B3. NAD can be reduced to NADH for redox reactions Flavin-Adenine Dinucleotide (FAD) another coenzyme, this one derived from riboflavin / B2 serves a similar function. FAD can be reduced to FADH 2 and carry hydrogens / electrons between reactions

Glycolysis in cytoplasm Glucose 2 ATP 2 NADH 2 Pyruvate 4 ATP Overview of Glycolysis 2 NADH 2 Pyruvate To mitochondria ATP For use in the cell for work

Sugars are not very reactive so to start the process 2ATP’s are used to add 2 phosphates to glucose in a series of three reactions generating Fructose 1,6 - bisphosphate

The phosphorylated sugar then breaks down into two 3 carbon molecules, one is glyceraldehyde phosphate the other is quickly converted into glyceraldehyde phosphate

1 st stage of glycolysis 2 ATP 2 ADP + 2 Pi

Glycolysis The two molecules of glyceraldehyde 3-phosphate will now go through each of the remaining steps in glycolysis producing two molecules of each product. As each of the two molecules of glyceraldehyde 3- phosphate are oxidized, the energy released is used to add an inorganic phosphate group to ADP to form two molecules of ATP per GALP ( 4 in total). During these oxidations a molecule of NAD+ is reduced to form NADH + H+ (2 in total)

2 ADP + 2 Pi 2ATP 2 ADP + 2 Pi 2ATP NADP 2 NADP NADP 2 NADP 2 nd Stage of Glycolysis

The Link Reaction Pyruvate easily enters the matrix of the mitochondria where it enters a circular pathway (Krebs cycle) which occurs within the matrix of the mitochondria. The first step is to convert pyruvate into a two- carbon fragment, then attach it to another coenzyme known as coenzyme A or CO-A. This is called the link reaction 2 molecules of NADH are also produced

The Link Reaction

Glycolysis Use all of the information today and the text book pages 11,12 and 13 to draw out the reactions of glycolysis with clear explanations of what is happening at each stage Hand in next lesson

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In Animals In the presence of oxygen pyruvate is transported into the mitochondria where it enters the next major metabolic pathway for the production of ATP energy. The citric acid cycle. Aerobic. If there is no oxygen present then the pyruvate is converted to a substance called lactate.