cellular respiration

• glycolysis is the first stage of respiration both aerobic and anaerobic.
• glycolysis occurs in the cytoplasm of the cell
• glycolysis involves the splitting of 6-carbon sugar (glucose) into two 3-carbon molecules, pyruvate.
• the four stages of aerobic respiration are glycolysis, link reaction, Krebs cycle and oxidative phosphorylation
• the double membrane of the mitochondria located around the organelle.
• the membrane controls the movement of materials in and out of the organelle.

  the inner part of the membrane is folded to form extensions as Cristae.
• cristae provides a large surface area for the attachment of enzymes and other proteins involved in respiration.
• the matrix makes up the remaining part of the mitochondria.

  it contains proteins, lipids, ribosomes, and DNA

  respiratory enzymes are usually found in the matrix of the mitochondria
• the four stages of glycolysis are:

  • phosphorylation of glucose to glucose phosphate
  • splitting of the phosphorylated glucose
  • oxidative of the triose phosphate
  • production of ATP
• in phosphorylation of glucose to glucose phosphate:

  • glucose is made more reactive by the addition of two phosphate molecules.
  • the phosphate molecules are produced from the hydrolysis of 2 ATP to ADP
• in the splitting of the phosphorylated glucose, each glucose molecule will split into 3-carbon molecules known as trios phosphate.
• in the oxidation of the triose phosphate, hydrogen is removed from each of the triose phosphate molecules and transferred to hydrogen carriers known as NAD.

  • NAD is reduced to NADH
• each triose phosphate will be converted to 3-carbon molecules, pyruvate

  2 ATP is generated from pyruvate
• glycolysis will produce two ATP molecules, two pyruvate and two NADH
• link reaction happens in the matrix
• in the link reaction, the pyruvate will be oxidized to acetate. it will lose one carbondioxide and two hydrogens.
• in link reaction, hydrogen will be accepted by NAD to form NADH to produce ATP
• the acetate in the link reaction will combine with coenzyme to form acetylcoenzyme A
• pyruvate ---> NAD + COA --> acetyle COA + NADH + CO2
• the kreb cycle take place in the matrix
• the 2-acetylecoenzyme will combine with 4-carbon molecule to produce 6-carbon molecule.
• the 6-carbon molecule loses CO2 and hydrogen to form 4 carbon molecule and a single molecule of ATP is produced from substrate level of phosphorylation
• the 4 carbon molecule can combine with a new molecule of acetylecoenzymeA to start the cycle again.
• the importance of Kreb cycle is that it produces hydrogen atoms carried by NAD and provides energy for oxidative phosphorylation

  it also produces 4 carbon molecules that combine with acetylecoenzymeA
• examples of coenzymes are NAD, FAD< and NADP in photosynthesis
• oxidative phosphorylation takes place in the inner mitochondrial membrane
• the products of oxidative phosphorylation are the production of many ATP and production of water from oxygen.
• in anaerobic respiration, there is no oxygen, which means:

  • no final acceptor of electrons from the electron transport chain
  • electron transport chain stops functioning
  • no more ATP is produced from oxidative phosphorylation
  • NADH and FADH are not oxidised by electron carrier
  • no oxidised NAD and FAD are available for deyhdration in kreb cycle
  • The Kreb cycle stops
• coenzyme are not enzymes but they help them to carry out their function but will not be used in the reaction itself