Distinguish between Glycolysis and TCA Cycle

Difference between Glycolysis and TCA Cycle

All living organisms carry out a series of chemical reactions that we commonly call metabolism. Within the metabolism there are reactions that have the function of synthesizing a very important molecule for the cell, called Adenosine Tri-Phosphate (ATP). This molecule known as ATP is responsible for storing energy in its bonds, that is, when this molecule is broken and its bonds are broken, we have the release of energy for cellular use.

As we Know Respiration is a Metabolic process that involved in series of chemical reactions that are oxidation and reduction and electron transfer reactionsp. Respiration are of two types aerobic and anaerobic respiration. At the end of both respiration organisms produce energy in the form of ATP for their metabolic Activities. During aerobic respiration oxygen molecules act as the final receptors for electrons and are reduced to produce water. This creates an electrochemical gradient that drives ATP synthesis. 

Read : Difference Between Actin and Myosin 

Aerobic respiration consists of three main phases, where carbon molecules rearrange through a series of enzyme-catalyzed reactions to produce ATP. The first phase, common in aerobes and anaerobes, is the glycolytic Pathway in which sugar act as substrate. Mainly glucose is catabolized and forms two molecules of pyruvic acid. This conversion produces two molecules of ATP and two molecules of NADH. 

The second phase is the tricarboxylic acid (TCA) cycle, which is the central reaction where intermediaries from all metabolic pathways come together to contribute to the process energy production by producing NADH, FADH2, and two CO2 molecules. Through oxidation-reduction reactions. The TCA cycle is occurs only in aerobes. In both processes, phosphorylation takes place at the substrate level to produce energy. The key difference between glycolysis and the TCA cycle is that glycolysis occurs in the cytoplasm, while the TCA cycle occurs in inside the mitochondria.

Distinguish between Glycolysis and TCA Cycle


Distinguish between Glycolysis and TCA Cycle

Glycolysis Kreb Cycle
Glycolysis is a metabolic process in which glucose (C6H12O16) is converted into Pyruvic Acid (CH3COCOOH). TCA cycle is series of chemical reactions used by all organism to release store energy through the oxidation of Acetyl CoA derived from Carbohydrates, fats  and Proteins
Glycolysis is also known as EMP pathway. Kreb cycle is also known as TCA cycle (Tri carboxylic acid cycle) or Citric Acid cycle.
Glycolysis is discovered by Embden, Meyerhof and Parnas in 1940. Citric Acid cycle is discovered  by Hans Kreb's
Glycolysis occurs in Cytoplasm Kreb cycle occurs in Matrix of Mitochondria
Glycolysis is the first step of aerobic respiration which produce two molecules pyruvate (3 carbon containing compound) after partial breakdown of glucose. Kreb cycle is the second step of aerobic respiration in which pyruvic acid is completely oxidised into organic substances and forms Co2
Glycolysis occurs in All living organisms TCA cycle occurs only in Aerobic Organisms that requires Oxygen for there growth and development.
Oxygen is not required in the process of glycolysis. Oxygen is Must for Kreb cycle
No Co2 Evolved Co2 evolved
Glycolysis takes place  in Aerobic and anaerobic respiration Tri carboxylic acid cycle takes place in Aerobic respiration.
Glycolysis occurs in linear sequence. It occurs in cyclic manner.
In glycolysis glucose act as substrate. In Creb Cycle Acetyl CoA Act as Substrate.
It produces Pyruvic acid, NADH and ATP. It produces oxalic acid, FADH2, NADH2, ATP and CO2.
Total Four ATP molecules are produced in glycolysis by One glucose molecules. One ATP or GTP molecules are produced by substrates level Phosphorylation in each turn of TCA cycle.


What is Glycolysis
  1. The glycolysis is most common metabolic process which is essential for life and performed by different cell types. 
  2. Glycolysis is a highly important metabolic pathway for the functioning of the cellular machinery. Because of this, glucose is the source of energy for cellular metabolism. 
  3. Glycolysis is the first of three steps in an extensive ATP production line. It occurs in both eukaryotic and prokaryotic Organisms and basically involves in breakdown of the glucose at the end of glycolysis it gives two molecules of pyruvic acid, four molecules of ATP and hydrogens that are carried by molecules called transporters (NAD and FAD).
  4. The glycolysis step occurs both in aerobic processes (which use oxygen), called aerobic respiration and in anaerobic processes (which do not use oxygen), called fermentation. One of the main difference between two types of glycolysis is the fate of the hydrogen carried by NAD+.
  5. The other steps after glycolysis are the Krebs Cycle (or Citric Acid Cycle), which takes place within the mitochondria in the mitochondrial matrix. Finally, the last step can be called the Respiratory Chain or Oxidative Respiration and it also occurs inside the mitochondria, but in membrane folds called mitochondrial crests.

What is TCA cycle  : 
  1. The citric acid cycle or Krebs cycle is a cyclic, amphibolic metabolic pathway that consists of eight enzyme-catalyzed individual steps . 
  2. It occurs in both eukaryotes and prokaryotes and is used to generate energy and provide intermediate products for the synthesis of important biomolecules such as amino acids.
  3.  The location of the citric acid cycle is the mitochondrion in eukaryotes  ( animals , plants , fungi) and the cytoplasm in prokaryotes . It takes place after glycolysis and then flows into the respiratory chain.
  4. Pyruvate or acetyl-CoA molecules can be obtained not only from carbohydrates (glucose), but also from the breakdown of amino acids (proteins) or fatty acids (fatty acid oxidation).
  5. The citric acid cycle also has other important functions: It represents the final route for the breakdown of amino acids that are not broken down into acetyl-CoA or pyruvate.
  6. It supplies starting materials for the synthesis of new amino acids such as oxaloacetate for aspartate.
  7. By branching off reaction products from the citric acid cycle, other metabolic pathways can be fed: citrate for fatty acid synthesis , oxaloacetate for gluconeogenesis or succinyl-CoA for the formation of δ-aminolevulinic acid as a starting material for heme synthesis.