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

How is NADPH produced in (a) Photosynthetic AND (b) Non-photosynthetic cells? How and where are ketone bodies (a) synthesised AND (b) utilised?

Extracts from this document...


´╗┐How is NADPH produced in (a) Photosynthetic AND (b) Non-photosynthetic cells? Give examples of how NADPH may be used in each case. NADPH is produced in photosynthetic cells by the light-dependent reactions of photosynthesis in order to be used for reduction of carbon atoms in the light-independent stage, or the Calvin Cycle. NADPH is produced in the light reactions which convert light energy into chemical energy. Photons absorbed by photosystem II in the thylakoid membrane, and the energy is used to break down water and release two electrons which are excited and begin to move along an electron transport chain in the membrane. As they move along, they release energy and pass through cytochrome bf, which is used to generate a proton-motive force and generate ATP until the electrons reach photosystem I. Photosystem I absorbs photons with wavelength 700nm and uses the energy to excite the electrons again, so that they can move further along the transport chain and eventually combine with NADP+ and H+ to give NADPH. ...read more.


The reaction pathway continues towards the 3-carbon sugars of glycolysis, but with no more generation of NADPH. This process is not only needed in non-photosynthetic cells, but also occurs in photosynthetic cells and even often in the chloroplasts of these cells where photosynthesis also occurs, or other plastids within plant cells. Furthermore, the transmembrane movement of malate and certain amino acids can also generate NADPH. How and where are ketone bodies (a) synthesised AND (b) utilised? Ketone bodies are primarily produced in the mitochondria of liver cells. They are synthesised in order to be transported for transport of acetyl-CoA so that all of these acetyl units can be oxidised ? for example, during starvation, gluconeogenesis depletes the supply of oxaloacetate which means that it cannot be used to combine with acetyl-CoA. Therefore, acetyl-CoA resulting from fatty acid breakdown must be oxidised in another way, in this case by conversion to ketone bodies. The ketone bodies are acetone, D-3-hydroxybutyrate and acetoacetate, and these are three water-soluble molecules which can pass through the blood-brain barrier (which acetyl-CoA cannot) ...read more.


This is generally not true in the brain, however, and so ketone bodies are only required in the brain in great concentrations when the body is glucose-deficient i.e. during times of starvation, but also as the primary source of energy in the renal cortex. It is in these cells that ketone bodies are converted to acetyl-CoA so that this can enter the TCA cycle. This conversion occurs when acetoacetate receives a CoA group from succinyl-CoA via catalysis by CoA transferase to give acetoacyl-CoA. This is then cleaved by thiolase to yield two molecules of acetyl-CoA, as this is the molecule needed for entry into the TCA cycle in order to generate NADH and FADH for use in oxidative phosphorylation to generate ATP. When the demand for acetyl-CoA becomes high in these cells, ketone bodies are transported to them instead of acetyl-CoA because the CoA transferase enzyme is not present in liver mitochondria so this must occur in the energy-requiring cell. Therefore, the ketone bodies act as a water-soluble, transportable form of acetyl units. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Microbiology section.

Found what you're looking for?

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

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 University Degree Microbiology essays

  1. Qualification and quantification of microorganisms in soil role of microorganisms in the nitrogen cycle.

    Soil Dark orange +++++ 9- Control Yellow pale + 10- Control Yellow pale + Table 7: Colour intensity and colouration after incubation when adding Nesslers reagent. Both soil tubes (7 and 8) display the darkest colouration, thus, according to the scale providing, the more production of ammonia occurred in those tubes.

  2. Nucleic acid hybridization

    PEG has a slightly better acceleration of hybridisation rates than dextran sulphate when single-stranded probes are used. Formamide 1. To lower the Tm of the duplexes and enable hybridisation at lower temperatures. 2. At lower incubation temperatures, the losses of target from the filter during hybridisation are reduced and the stability of RNA probe is increased.

  1. Microbes in Soil - Helping a Carbon Source or Sink?

    Hence can we store the carbon in soil and reduce the number of CO2 in the atmosphere? Elevated atmospheric CO2 can have indirect effects on soil microbial communities via altered plant inputs (litter, exudates, and rhizodeposition). Carney et al [6] reported that soils from elevated CO2 area demonstrated higher rate of microbial respiration.

  2. Investigation into the effect of Temperature on the action of the Enzyme Lipase.

    In other words at higher temperatures bonds are broken which mean that the lipase enzyme key can no longer fit in the milk substrate lock (diagram of lock and key hypothesis is show below as diagram A). This process is called denaturing.

  1. The role of ATP and NAD / FAD in Respiration.

    The hydrogen removed from pyruvate is transferred to NAD. Fatty acids from fat metabolism may also be used to produce acetyl coenzyme A. Fatty acids are broken down in the mitochondrion in a cycle of reactions in which each turn of the cycle shortens the fatty acid chain by a two carbon acetyl unit.

  2. The Energy Levels of Molecules

    For a mole of gas the total energy is called the Internal Energy of the System (U / KJ mol-1). This is the sum of each of the individual values of ETotal for each of the 6.0223 ? 1023 molecules in the system..

  1. Essay Writing On The Formation Of A.T.P

    The glycerate-3-phosphate loses a hydrogen atom, which is transferred on the NAD molecules to turn the molecule into reduced NAD (NAD H+). This last stage also produces 2 ATP molecules on each glycerate-3-phosphate molecule by converting the earlier productions of ADP + Pi back into ATP.

  2. Compare and Contrast Eukaryotic and Prokaryotic Cells

    Diagram A very good diagram illustrating these similarities and differences [l]is below ? the top two cells (animal and plant cells) are eukaryotic, whereas the lower bacteria cell is a prokaryote[m]. cell: typical cells This comes from Encyclopaedia Britannica from their website: http://www.britannica.com/EBchecked/topic/422009/nucleus Sources Lecture notes ? ?the living cell?,

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