Glycolysis Overview and Function

Glycolysis Overview

• Glycolysis is a metabolic pathway that creates ATP without oxygen.
• It occurs in the cytoplasm of the cell.
• Glycolysis can occur in the presence or absence of oxygen.
• It's essential for anaerobic organisms.
• It's vital for cells experiencing low oxygen, like red blood cells and muscle cells during intense exercise.
• Glycolysis derives from combining two Greek words: glyks (sweet) and lysis (breakdown/splitting).
• It's also known as the Embden-Meyerhof-parnas (EMP) pathway.

Function of Glycolysis

• Glycolysis precedes lactic acid fermentation.
• Pyruvate made in glycolysis serves as the prerequisite for lactate in lactic acid fermentation.
• Lactic acid fermentation is the primary ATP source in animal tissues with limited mitochondria.
• In red blood cells, lactic acid fermentation is the sole ATP source due to lack of mitochondria.
• The lens of the eye relies on anaerobic glycolysis as it lacks mitochondria.

Two Phases of Glycolysis

• Phase 1: Preparation Phase

  • Two phosphates are added to glucose.
  • Hexokinase phosphorylates glucose to glucose-6-phosphate (G6P).
  • Glucose is enzymatically phosphorylated by ATP to fructose-1,6-bisphosphate.
  • Fructose-1,6-bisphosphate is split into two molecules of three-carbon glyceraldehyde-3-phosphate/ dihydroxyacetone phosphate.

• Phase 2: Payoff Phase

  • Glycolysis has a cost of 2 ATP molecules while producing 2 small 3-carbon sugar molecules.
  • Includes glyceraldehyde-3-phosphate (G3P).
  • This energy input creates various chemical pathways.

Significance and Historical Perspective

• Glycolysis is crucial for cellular survival.
• It provides a rapid and efficient means of generating ATP, even in the absence of oxygen.
• Eduard Buchner discovered cell-free fermentation in the 1890s.
• Otto Meyerhof linked various glycolysis pieces and recreated the pathway in muscle tissue in the 1920s.
• Gustav Embden outlined a step-by-step glycolytic pathway in the 1930s.
• Arthur Harden and William Young identified the regulatory effects of ATP and discovered fructose-1,6-bisphosphate as a glycolysis intermediate in the early 1900s.

Glycolysis in a Simple Term

• Video to explain glycolysis in the form of an animated short story to help learn the process easier.

Quiz Time

• Question 1: What is the main purpose of glycolysis?

  • To produce ATP.

• Question 2: Which molecule is the final product of glycolysis?

  • Pyruvate

• Question 3: In which part of the cell does glycolysis occur?

  • Cytoplasm

• Question 4: How many ATP molecules are produced in the energy generation phase of glycolysis?

  • 2

• Question 5: Which of the following intermediates is produced during the breakdown of glucose in glycolysis?

  • Glyceraldehyde-3-phosphate (G3P)

• Question 6: Which enzyme catalyzes the first step of glycolysis?

  • Hexokinase

• Question 7: Which molecule is used to convert glucose into glucose-6-phosphate in glycolysis?

  • ATP

• Question 8: What is the net ATP yield of glycolysis?

  • 2

• Question 9: Which step of glycolysis is irreversible and highly regulated?

  • The conversion of fructose-6-phosphate to fructose-1,6-bisphosphate

• Question 10: Which coenzyme is required for the oxidation of G3P in glycolysis?

  • NAD+