Introduction

• Glycolysis only occurs in the cell cytoplasm.

• It is an enzyme catalysed reaction.

• It literally means ‘carbohydrate splitting’.

• It is a part of both aerobic and anaerobic respiration.

• Due to this, it is sometimes referred to as the ‘Common Pathway’.

• Glycolysis will occur whether the organism respires aerobically or anaerobically.

• This means that there is no involvement of oxygen.

• Glycolysis occurs outside of the mitochondria, making it different to the other stages of respiration.

• Glycolysis turns glucose into pyruvate through the ‘splitting’ of the glucose.

Graph

Stages

• Glucose (a six carbon molecule) turns into glucose phosphate. This is done through the phosphorylation of glucose, which results in glucose becoming more reactive. The phosphate is a result of the ATP being hydrolysed into ADP. Glycolysis requires 2 ATP molecules that turn into 2 ADP molecules and 2 phosphate ions.

• The ATP provides energy for the glucose phosphate (a six carbon molecule) to split into two three carbon molecules known as triose phosphates.

• The triose phosphates get oxidised. This is due to the removal of hydrogen from each of the triose phosphate molecules.

• The triose phosphates then turn into pyruvate. This is caused by the removal of hydrogen and the substrate level phosphorylation. An extra phosphate ion attaches itself to each of the triose phosphates. By the end two pyruvate, two reduced NAD and four ATP molecules are produced. As only two ATP molecules are required in Glycolysis but four are produced, it means that there is a net gain of ATP.