respiration

• Glycolysis is the first stage in both aerobic and anaerobic respiration. This means that glycolysis…

  does not require oxygen
• where does glycolysis take place in?

  cytoplasm
• what does glycolysis produce molecules with?

  3 carbon atoms
• During glycolysis, glucose is converted into two identical molecules containing three carbon atoms. what are the three-carbon molecules are called?

  Pyruvate
• Describe the first stage of glycolysis

  an enzyme adds 2 phosphate groups to glucose. This process is known as phosphorylation and produces a new molecule called glucose phosphate. These phosphate groups are available due to the breakdown of two molecules of ATP.

  
• In the second step of glycolysis, glucose phosphate breaks down into two molecules of…

  triose phosphate.
• The conversion of a single triose phosphate molecule to pyruvate produces…

  2 ATP molecules.
• For a single glucose molecule undergoing glycolysis, there is an overall yield of 2 ATP molecules.
• what substance is reduced and oxidised during glycolysis?

  triose phosphate - oxidised

  NAD - reduced
• Describe how oxidation-reduction is involved in glycolysis.

  Triose phosphate loses hydrogen in the third step of glycolysis, so triose phosphate is oxidised.This hydrogen is transferred to a molecule called NAD, forming NADH or reduced NAD.
• Alongside pyruvate and ATP, what else is produced during glycolysis?

  NADH (reduced NAD)
• Describe the process of glycolysis. Ensure that all products formed are mentioned.

  1. glucose enters the cell’s cytoplasm. Upon entry, an enzyme adds two phosphate groups to glucose in a process known as phosphorylation. These phosphate groups are available due to the breakdown of 2 ATP molecules. This produces glucose phosphate.
  2. hexose phosphate breaks down into two molecules of triose phosphate.
  3. triose phosphate is converted into pyruvate. In this step, 2 molecules of NADH and 4 molecules of ATP are formed.The overall yield of ATP within glycolysis is 2 ATP.
• At the end of glycolysis how many molecules of pyruvate are we left with?

  2
• After glycolysis, pyruvate is…

  actively transported into the mitochondrial matrix.
• what is the 2nd stage of aerobic respiration called?

  the link reaction
• pyruvate -> acetate -> Acetyl-CoA
• what type of molecule is NAD?

  Coenzyme
• describe the link reaction

  takes place in the matrix of the mitochondria. In the first step of the link reaction, pyruvate is converted to a molecule called 

  acetate as a carbon is lost in the form of carbon dioxide. A hydrogen atom is also lost from pyruvate, which is transferred to a molecule of NAD to produce NADH. In the second step of the link reaction, a molecule called CoA (coenzyme A) is added, which forms a new molecule called acetyl-CoA.

  
• Two carbon atoms are lost during the Krebs cycle. What are lost in the form of?

  CO2
• what is the 3rd stage of aerobic respiration?

  Krebs cycle
• In the Krebs cycle, acetyl-CoA reacts with a molecule containing how many carbon atoms?

  4 forming a 6 carbon molecule
• the reaction of the 4 carbon molecule with acetyl-CoA is catalysed by an enzyme.

  To function properly, this enzyme needs a coenzyme = coenzyme A.

  CoA ensures that the Krebs cycle takes place
• How is ATP made?

  By substrate-level phosphorylation during both glycolysis and the Krebs cycle.
• Name all the products of the Krebs cycle.

  reduced FAD, ATP, CO2 and NADH
• In the Krebs cycle, what does acetyl CoA react with?

  a 4 carbon molecule to produce a 6 carbon molecule.
• Describe fully the Krebs cycle, including details about all the molecules that are produced.

  Acetyl CoA produced in the link reaction enters the Krebs cycle, where it reacts with a molecule containing 4 carbons to produce a new molecule containing 6 carbons. Coenzyme A is removed in this reaction. Then, in a series of oxidation and reduction reactions, the 6-carbon molecule is converted back into the 4-carbon molecule. Carbon dioxide is produced as two carbon atoms are lost. In addition, for every acetyl CoA molecule that enters the Krebs cycle, 1 ATP molecule is produced as an ADP molecule reacts with a phosphate group. Also, intermediate molecules in the Krebs cycle lose hydrogen atoms, which reduces NAD and FAD to produce NADH and FADH2​ respectively.
• To be used in respiration, triglycerides are broken down into…

  glycerol and 3 fatty acids.
• Which stage of aerobic respiration is pyruvate used in?

  the link reaction
• In aerobic respiration, the majority of amino acids containing three carbons are converted to…

  pyruvate - the link reaction
• In aerobic respiration, the majority of amino acids containing four or five carbon atoms are converted into molecules which are used in…

  the Krebs cycle
• respiration

  glycolysis, link reaction and Krebs cycle

  
• Which stage(s) of aerobic respiration take place in the mitochondria?

  Krebs cycle and link reaction
• In which stage(s) of aerobic respiration is NADH produced?

  all 3
• To catalyse the production of ATP, ATP synthase needs energy. Where is the energy supplied by ?

  diffusion of protons down a proton gradient.
• To produce ATP in the final stage of aerobic respiration, an enzyme called ATP synthase is used.To catalyse the production of ATP by this enzyme, energy is supplied through the diffusion of protons down a proton gradient. As a result, these particles move from the intermembrane space to the matrix.The movement of ions across a partially permeable membrane, from an area of a high concentration to an area of low concentration = chemiosmosis.
• how is the proton gradient maintained?

  proteins move the protons by the process of active transport
• Where would we expect to find a higher concentration of protons?

  intermembrane space
• How do these protons move through the proteins?

  by active transport
• what do electrons at the end of the transfer chain react with to form?

  protons and oxygen to form water
• what is oxygen known as?

  final electron acceptor