• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Cellular Respiration and the Role of Mitochondria

Extracts from this document...


Cellular Respiration and the Role of Mitochondria Cellular respiration is the process of oxidising food molecules, such as glucose, to carbon dioxide and water and releasing the covalent bond energy in the form of ATP for use by all the energy-consuming activities of the cell. Mitochondria are membrane-enclosed organelles distributed through the cytosol of most eukaryotic cells. They are where cellular aerobic respiration occurs; indeed cells without mitochondria cannot respire aerobically. Cellular respiration consists of two broad phases, initially, glycolysis (the breakdown of glucose to pyruvic acid) Occurs, this is followed by the oxidation of pyruvic acid to carbon dioxide and water. In eukaryotes, glycolysis occurs in the cytosol (The fluid in which cell organelles are suspended). The remaining processes take place in the mitochondria. The first stage, glycolysis is the anaerobic catabolism of glucose, it occurs in almost all cells. ...read more.


The electrons of NADH and FADH2 are transferred to the respiratory chain. The final step regenerates a molecule of oxaloacetic acid and the cycle is ready to turn again. The four complexes of integral membrane proteins that make up the respiratory chain accomplish the stepwise transfer of electrons from NADH (and FADH2) to oxygen atoms to form (with the aid of protons) water molecules (H2O). The energy released is harnessing by the pumping of protons (H+) from the matrix to the intermembrane space. Protons are then pumped at 3 (of the four) complexes, NADH dehydrogenase, cytochrome c reductase and cytochrome c oxidase. An average of 3 protons is pumped out at each complex as each pair of electrons passes through it. Thus some 9 protons are pumped for each pair of electrons contributed to the respiratory chain by NADH; (6 for each pair contributed by FADH2). ...read more.


The process is called chemiosmosis and is an example of facilitated diffusion. The energy stored in the proton gradient is used for a number of other mitochondrial functions such as the active transport of a variety of essential molecules and ions through the mitochondrial membranes. NADH is also used as reducing agent for many cellular reactions. So the actual yield of ATP as mitochondria respire varies with conditions. It is generally regarded as seldom reaching 30 Mitochondria are vital to the proper function of almost all cells (the only exceptions being a few species of yeast's) because of the role they play in cellular respiration, they do however, unusually have their own DNA in the form of plasmids within the inner membrane. It is believed that mitochondria are the evolutionary descendants of a prokaryote that established an endosymbiotic relationship with the ancestors of eukaryotic cells early in the history of life on earth. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

4 star(s)

A good descriptive summary but further explanation and diagrams are really needed to make the information accessible.

Marked by teacher Adam Roberts 29/05/2013

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Enzyme activities

    In the presence of a protease,casein will be digested to give a clear zone in milk-agar plate. The degree of clearness can be used as an indication of protease activity. The clear zone of the pineapple is very clear and it have the longest diameter(15mm), it show that pineapple have the greatest protease activity.

  2. The Effect of Concentration on Pectinase Using Apple

    0.1 0.10 210 0.1 0.2 0.1 0.13 240 0.2 0.2 0.1 0.17 270 0.2 0.2 0.2 0.20 300 0.2 0.2 0.2 0.20 Total Volume 2.5 2.5 2.6 2.53 This is a graph to show the above results more easily. The average volumes for every 30 seconds have been plotted for each concentration, up to and including 300 seconds.

  1. The investigation to find the effect of glucose concentration on fermentation of yeast.

    However if we keep increasing the substrate concentration keeping the enzyme concentration constant, there comes a point where every enzymes active site is working constantly, if more substrate is added the enzyme simply cannot work faster substrate molecule are effectively 'queuing up' for an active site to became vacant the

  2. Introduction to Cellular Respiration in Yeast.

    � thermometer PROCEDURE: 1. A hot bath was set up by filling a 1000mL beaker with 300mL of water and placing it on the hot plate. 2. The basin filled with sufficient water. A graduated cylinder was filled with water and flipped upside-down while partially submerged (so that no water escaped from the graduated cylinder).

  1. Does ethanol causes greater inhibition of pig liver catalase than of yeast catalase

    This was clearly true for both types of catalase. What the processed data shows though is that there wasn't a massive gap between the effects of the ethanol on the yeast and the pigs liver catalase. In the processed data you can see that the pigs liver gets inhibited a

  2. The effects of smoking on the respiratory system.

    The walls of the pharynx are composed of skeletal muscle and again are lined with a mucus membrane. Persistent smokers can scorch the delicate tissues that line the back of the pharynx causing painful blisters. Cells lining this area are damaged and eventually die.


    then the equilibrium of the systems changes: ? = ?p + ?s A measure of the tendency of a system or cell to give up water to another system. Water flows from a higher to a lower water potential, so any system with a positive will pass water into a system with a zero or negative .

  2. An experiment to find of the isotonic point of root vegetables cells in contents ...

    it should have the lowest isotonic point as the point where the net movement of water is equal will occur quicker hence at this point there will be no change in mass and length. I predict that in terms of ranking the root vegetable with the highest isotonic point will be: 1.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work