Tag Archives: Glycolysis

Publish Paper 1 Review – Regional Aerobic Glycolysis.

S. Neil Vaishnavi, M. E. R. 2010. Regional aerobic glycolysis in the human brain. Accessed 8th April 2014. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2955101/

In this paper an experiment using 33 right-handed neurologically normal young adults at rest was used to calculate the regional distribution of aerobic glycolysis using positron emission tomography. Aerobic glycolysis can be defined as the state where glucose metabolism exceeds that used for oxidative phosphorylation despite sufficient oxygen to metabolize glucose to carbon dioxide and water. It was stated that aerobic glycolysis normally increases with increase cellular activity. This experiment was used to further help understand the role of glycolysis in the human brain at rest. Also to determine whether there is variations in glycolysis in the brain and how this in turns affect overall brain energy utilization.
Aerobic glycolysis is traditionally assessed in terms of the molar ratio of oxygen consumption to glucose utilization and a number less than 6 is indicative anerobic glycolysis is present. From the results gathered it was seen that the regions of the brain with high aerobic glycolysis included prefrontal cortex, lateral parietal cortex, posterior cingulate/precuneus, lateral temporal gyrus, gyrus rectus, and caudate nuclei. Whereas low aerobic glycolysis was found in the inferior temporal gyrus and throughout the cerebellum. Thus from the results it can be seen that the levels of aerobic glycolysis are not strictly related to the levels of brain energy metabolism but factors for ongoing aerobic glycolysis in the brain may be: 1) Energy – because the brain needs to suport membrane bound processes which needs ATP it would need to perform aerobic glycolysis to get the required energy. 2) Biosynthesis and 3) redox states.
Therefore from this research it can be seen that not only brain activity affects the level of aerobic glycolysis but there may be many other contributing factors. Thus research in this area should continue as it may help in the prevention/ curing of brain functioning related diseases.

This article is very appealing and everyone interested in biochemistry should take a look at it!!!! 🙂

GLYCOLYSIS

This week is all about glycolysis…… It is a bit difficult to grasp at first but with a little time and alot of drawing you would get it!!!!!!!

All tissues use the glycolytic pathway for the breakdown of glucose to provide energy. This energy is in the form of ATP.

Glucose to pyruvate takes place in two stages these are:

The first five reactions of glycolysis correspond to an energy investment stage

The other five reactions of glycolysis constituted energy generating stage

Below shows a diagrammatic explanation of the steps in glycolysis it is simple yet effective.

13_01Glycolysis-Steps_1-5

13_01Glycolysis-Steps_6-10

The Fate of Pyruvate

Diagram showing the fate of pyruvate under different conditions:

pyruvate

Aerobic conditions

FATE NUMBER 1:

This is where pyruvate is converted to acetyl CoA. The enzyme pyruvate dehydrogenase (PDH) uses Thiamine prophosphate (TTP) to catalyse the  reaction. It is irrevisible.

NOTE: The most ATP is generated in this fate.

Anaerobic conditions

These two fates can sometimes  be referred to as fermentation.

This process helps regenerate NAD+.

FATE NUMBER 2

Pyruvate is converted to lactate by the enzyme lactate dehydrogenase (LDH).

FATE NUMBER 3

Pyruvate decarboxylase uses TPP to convert pyruvate to acetaldehyde

THEN

Using alcohol dehydrogenase acetaldehyde is convert to ethanol

NADH is converted to NAD+

NOTE: No ATP is generated.

 

 Feeder Pathways for Glycolysis

In glycolysis most carbohydrates except glucose are  transformed into one of the glycolytic intermediates:

1.     The storage polysaccharides glycogen and  starchh

2.   The disaccharides maltose, lactose, trehalose and sucrose

3.    The monosaccharides  fructose, mannose and galactose

Metabolism of Fructose

takes place via two  routes

1. Adipose tissue muscle and kidney

Fructose                    to  (enzyme used is Hexokinase )                                      Fructose 6 phosphate

It can then undergo glycolysis

2.  In the Liver

The enzyme used is glucokinase this does not phoshorylate the frustose. Here fructose is metabolised.

POINTS TO NOTE:

  • Glycolysis takes place in the cytosol of  cells.
  • There are two phases  in glycolysis  these are: The Energy investment phase & Energy generation phase
  • Glycolysis produces 2 pryuvate  molecules.
  • ATP is initially  needed.
  • ATP is  generated.
  • The fate of the pryuvate form differs depending on the conditions.
  •  There is a disease called Galactosemia which  is a genetic disease caused by the inability of the body  to convert galactose to glucose.

REFERENCES

https://www.google.tt/search?q=fates+of+pyruvate&espv=210&es_sm=93&tbm=isch&imgil=x7vITESRmLrS3M%253A%253Bhttps%253A%252F%252Fencrypted-tbn0.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcQBnmmjP4QoGkFv9-hWtcF2lSsuSCaPIqiIG8owpGMHuzxDeq582g%253B640%253B372%253Bol0s-ZnMxbjT0

https://www.google.tt/search?q=glycolysis&espv=210&es_sm=93&source=lnms&tbm=isch&sa=X&ei=ybUfU6TFF8udkQe6-4HQAQ&ved=0CAkQ_AUoAQ&biw=1092&bih=507#facrc=_&imgdii=_&imgrc=Ef2-LosnGEc9sM%253A%3BkmJmFJLj3xG4hM%3Bhttp%253A%252F%252Fwww.accessexcellence.org%252FRC%252FVL%252FGG%252Fecb%252Fecb_images%252F13_01Glycolysis-Steps_6-10.jpg%3Bhttp%253A%252F%252Fwww.accessexcellence.org%252FAB%252FGG