Рũßłїѕђёď åŗțїćłё #2

 Mattar et al. 2012. ‘Lactose intolerance: diagnosis, genetic and clinical factors.’ Accessed March 28, 2013. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3401057/

Lactose intolerance: diagnosis, genetic and clinical factors:

Lactose is a carbohydrate found in milk. This disaccharide is made up of glucose and galactose subunits. Seventy five percent of the world’s population loses their ability to breakdown the disaccharide into monosaccharide units that are easily digested. Lactase is the enzyme that breaks down lactose products. In infants breakdown is at its max from birth till 2 years. An aging person can fall into a group of lactase non-persistence (hypolactasia) or lactase-persistence activities. Reduction in lactose renders persons lactose intolerant that develop symptoms in identifying the presence of this diagnosis. 

            Individuals with hypolactasia and lactase persistence have identical coding sequences which were confirmed in a study where DNA was collected from subjects in various parts of the world. The LCT-13910CT and LCT-13910TT genotypes were associated with the lactase-persistence phenotype. This indicates that it dominates the person where they is a lactose digester. If the genotype was LCT- 13910CC and LCT-13910T is absent the person suffers from lactose mal digestion.

            The first method for detection of lactose mal digestion was direct biochemical assay of lactase activity from a jejunal sample. This was performed using a glucose oxidase reagent which detects glucose molecules present in the lactose. This method has been replaced by endoscopic duodenal biopsy. The lactose breath test is also a method for determining the presence of lactose in the body. It is based on fermentation of undigested lactose by intestinal flora producing hydrogen, carbon dioxide and methane which is absorbed and eliminated via the lungs. The result of these gases is bloating, abdominal pain, and diarrhea. Undigested lactose acidifies the colon and increases diarrhea while some may experience constipation.

            A false-negative result can occur if antibiotics have been recently consumed within one month of testing or if the pH is too acidic to inhibit bacterial activity or if there has been bacterial growth. The genetic test provides a more direct result where hypolactasia or lactase persistence genotype is found. This was formed due to the discovery of lactase-persistence alleles. This method was deemed better than the breath test since there is no cut off level or dependence on the amount of lactose or influenced by the duration of the test and age of the individual.

            Individuals suffering with this problem need to maintain their intake of calcium due to their restricted milk diet. A deficient in calcium result in bone diseases. A key to management of lactose intolerance is a recommended of no more than 20g of lactose without significant symptoms. A person’s diet changes where they would have to consume it with other foods and prevent lactose tablets. Supplements of calcium and vitamin D are produced which may be expensive to the consumer.  Yoghurt containing live cultures providing endogenous beta galactosidase is an alternative source of calories and calcium and is well tolerated by many lactose-intolerant patients. Lactose hydrolyzed milk is another safe source for patients.

            This article cleared up the effects of an individual suffering from the absence of the enzyme called lactase which breaks down lactose found in dairy products such as milk. It enhances the symptoms of a patient suffering from lactose intolerance and deals with the different mechanisms of detecting lactose in the body and suggests which method is better due to the information gathered.

            Hope you learned something as well…

45

Fermentation is an anaerobic process in which energy is released from glucose in the absence of oxygen. It occurs in yeast cells, erythrocytes, bacteria and in the muscle cells of animals.

pyruvate

FERMENTATION IN YEAST

a1

In yeast cells glucose is metabolized through cellular respiration as in other cells. However, when oxygen is lacking glucose is still metabolized to pyruvic acid (pyruvate) via glycolysis. The pyruvate is first converted to acetaldehyde by the enzyme pyruvate decarboxylase and then to ethyl alcohol by the enzymic process of alcohol dehydrogenase. There is no net gain or loss just regeneration of NAD+. This process is essential because it removes electrons and hydrogen ions from NADH during glycolysis. The effect is to free the NAD so it can participate in future reactions of glycolysis.
Yeast is used in bread and alcohol production. Alcohol fermentation is the process that yields beer, wine, and other spirits. The carbon dioxide given off during fermentation supplements the carbon dioxide given off during the Krebs cycle and causes bread to rise.

yeastbuds       bread     images (2)

FERMENTATION IN MUSCLE CELLS

lactferm

When muscles contract too frequently (as in strenuous exercise) they rapidly use up their oxygen supply. As a result, the electron transport system and Krebs cycle slows down as well as ATP production. However, muscle cells have the ability to produce a small amount of ATP through glycolysis in the absence of oxygen. The muscle cells convert glucose to pyruvate. Then the enzyme lactate dehydrogenase in the muscle cells converts the pyruvic acid to lactic acid. This reaction regenerates NAD+. Eventually the lactic acid buildup causes intense fatigue and the muscle cell stops contracting.
randy-orton-246        300px-Illu_muscle_structure

References:

http://www.cliffsnotes.com/study_guide/Fermentation.topicArticleId-8741,articleId-8606.html

http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookglyc.html

red-cell,.

What is Hemolytic Anemia?

It is a condition in which red blood cells are destroyed and removed from the bloodstream before their normal lifespan is over. Hemolytic anemia occurs when the bone marrow is unable to replace the red blood cells that are being destroyed. Hemolytic anemia is a type of anemia. The term “anemia” usually refers to a condition in which the blood has a lower than normal number of red blood cells.

You may not have symptoms if the anemia is mild. If the problem develops slowly, the first symptoms may be:

  • Feeling grumpy
  • Feeling weak or tired more often than usual, or with exercise
  • Headaches
  • Problems concentrating or thinking

If the anemia gets worse, symptoms may include:

  • Blue color to the whites of the eyes
  • Brittle nails
  • Light-headedness when you stand up
  • Pale skin color
  • Shortness of breath

  • Sore tongue

Glucose-6-phosphate dehydrogenase (G6PD or G6PDH) is an enzyme in the pentose phosphate pathway – a metabolic pathway that supplies reducing energy to cells such as erythrocytes by maintaining the level of the   co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH). The NADPH in turn maintains the level of glutathione in these cells that helps protect the red blood cells against oxidative damage. Of greater quantitative importance  G6PD reduces nicotinamide adenine dinucleotide phosphate (NADP) to NADPH while oxidizing glucose-6-phosphate. This NAD needs to present for erythrocyes to survive by making its energy and completing glycolysis. 


References:

http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/pentose.htm

http://www.pathologystudent.com/?p=1106

http://www.nlm.nih.gov/medlineplus/ency/article/000571.htm

http://www.nhlbi.nih.gov/health/health-topics/topics/ha/

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001597/

Ńέω Țσpїς ―› ●Ģłγςσļγšїš●

Steps in GLYCOLYSIS:

glycolysis_gif

From this week the new topic to be investigated by this blogger is…can you guess? Yes it is Glycolysis. First let me start with a definition of glycolysis: it is a metabolic pathway which takes place in every single cell in its cytosol. It does not have any specific organelle to take place in but uses the cell’s cytosol for its purpose.

There are ten reactions which takes place in this pathway involving the use of 3 irreversible and 7 reversible reactions. It is divided into two stages:

Preparatory Phase

STEP 1. glucose is converted to glucose 6-phosphate by the enzyme hexokinase which is an irreversible reaction. One molecule of ATP is used for this conversion.

[Irreversible reaction is where delta G – activation energy has a high negative value therefore if it was to go in the opposite direction it would require a high positive activation energy]

STEP 2. glucose 6-phosphate is converted to fructose 6-phosphate with the use of the enzyme phosphohexose immerase which is a reversible reaction.

[Reversible reaction is where the delta G is close to zero and it can go in both directions]

STEP 3. fructose 6-phosphate is converted to fructose 1,6 bisphosphate by the aid of the enzyme phosphofructokinase-1 (PFK-1). Another molecule of ATP is used for this conversion.

[Did you know? PFK-1 is the most regulated enzyme in glycolysis]

STEP 4. fructose 1,6 bisphosphate is then converted to glyceraldehyde 3-phosphate (G3P) and dihydroxy acetone phosphate (DHAP) by the enzymic reactions of aldolase.

[DHAP does not enter the second phase of glycolysis]

STEP 5. the enzyme triose phosphate isomerase comes into play to convert DHAP to a molecule of G3P.

[G3P and DHAP are isomers of each other]

Payoff Phase

STEP 6. glyceraldehyde 3-phosphate (2 molecules) is converted to 1,3 -bisphosphoglycerate (1,3- BPG) (2 molecules) by glyceraldehyde 3- phosphate dehydrogenase. Both and oxidation and phosphorylation reaction occurs at this step.

[Oxidation= 2NAD+ → 2NADH]

[Phosphorylation= 2Pi inorganic phosphates are added to carbon 3 on 1,3 BPG]

STEP 7. 1,3 -bisphosphoglycerate (2) is converted to 3-phosphoglycerate (2) by phosphoglycerate kinase. Two molecules of ATP is generated from this conversion and is broken even since ATP used in the first phase is compensated at this point.

[Substrate level phosphorylation- generation of ATP in glycolysis]

STEP 8. 3-phosphoglycerate (2) is converted to 2-phosphoglycerate (2) by phosphoglycerate mutase. The phosphate group is moved from carbon 3 to carbon 2.

STEP 9. 2-phosphoglycerate (2) is converted to phosphoenolpyruvate (2) by the enzymic reaction of enolase. It is a dehydrtion reaction since 2 molecules of water is lost.

STEP 10. phosphoenolpyruvate (2) is converted to pyruvate by pyruvate kinase. Two molecules of ATP is formed.

For every glucose molecule entering glycolysis 2ATP and 2NAP+ is used and 4 ATP  and 4 NADH generated.

NET GAIN:- 2 ATP and 2 NADH

References:

http://windsor.edu/Assi_model.htm