ALBINISM…..AN ERROR OF “ METABOLISM”

1. ALBINISM…..AN ERROR OF “METABOLISM”

2. Metabolism Definition : • Metabolism is the sum of chemical reactions, that occur within the body /an organism, in order to maintain life. • One of the functions - to obtain energy for the cell. Many chemical reactions are associated with energy changes.

3. Intermediary Metabolism - An Overview Energy and Bioenergetics Metabolism Molecular approaches to study metabolism

4. Energy is required for a whole range of biochemical processes that occur within an organism to maintain life • Muscle contraction • Active transport • Biosynthesis of molecules • Maintenance of body temperature

5. Energy Definition : Energy is the capacity to do work. • Forms of energy • Mechanical Energy • Heat Energy • Electrical Energy • Chemical Energy

6. TYPES OF CHEMICAL REACTIONS • Exergonic: Energy releasing processes, ones that "generate" energy, are termed exergonic reactions. Here, ∆G(free energy change) is a negative number, i.e., there is a net loss of energy, and the reaction goes spontaneously. • Ex: • ATP ADP+Pi+7.3KCal ∆G= -7.3KCal • 2.Endergonic: energy must be added to the system to make the reaction take place. Here, ∆G is a positive number, there is a net gain of energy, and the reaction does not go spontaneously. • Ex: A+B+5KCal AB ∆G= +5KCal

7. Coupled reaction • Chemical reaction with a common intermediate in which energy is transferred from one side of the reaction to the other. Ex: A+B+ATP AB+ ADP + Pi ∆G = -2 (Pi is common on both sides) • Living systems couple reactions in several ways, but the most common method of coupling reactions is to carry out both reactions on the same enzyme.

8. Spontaneous reaction / non enzymatic reaction A reaction that takes place on its own without an external force and another reaction needed to drive it. ∆G = Negative.

9. Bioenergetics a branch of science that deals with how a living organism converts food, sunlight, etc., into useful energy. Living organisms act as “transducers”.

10. Biologic systems use chemical energy to power living processes. • How Organisms convert Food(Fuel) To Energy is basic for the understanding of normal nutrition and metabolism • Starvation and malnutrition are associated with energy imbalance Depleted energy reserves Disease Death Biomedical importance

11. Thyroid hormones control the rate of energy release (metabolic rate), and disease results when they malfunction. • Excess storage of surplus energy • obesity, predisposes to many diseases • cardiovascular disease ; Diabetes mellitus II • lowers life expectancy.

12. An adult human being -1920–2900 kcal energy / day. • depends on physical activity.

13. Total energy requirement - Diet - proximate principles of food.

14. Energy source Energy yield / gm Carbohydrate Fat Protein 4 Cal 9 Cal 4 Cal Diet 1 calorie (symbol: cal) is equal to energy needed to increase the temperature of 1 gram of water by 1 °C. This is about 4.2 joules 1 Kilo calorie = 1 Cal (symbol: C; Cal) = 1,000 calories

15. Oxygen

16. Chemical energy in metabolic fuels Glucose Fatty acids Amino acids (Fuel molecules) Energy is present as C–H bonds referred to as reducing equivalents Transferred as H atom with its electron (1 reducing equivalent  transfer of 1 hydrogen atom transfer of 1 electron).

17. ATP • heat Oxidation CO2 + H2O Metabolic Fuel Energy substrate level phosphorylation (minor source) Reducing equivalents NADH; FADH2 ATP Oxidative phosphorylation (major source) ETC

18. METABOLISM • Definition Metabolism is the sum of chemical reactions in the body or in an organism in order to maintain life. • Main Function • Obtain energy for the cell.

19. BIOMEDICAL IMPORTANCE Normal metabolism + adaptation to physiological variations • Essential for an understanding of abnormalities underlying disease Starvation Excercise Pregnancy Lactation

20. BIOMEDICAL IMPORTANCE …… Derangements of metabolism maybe due to (i) Nutritional deficiency and excess (ii) Inborn errors of metabolism Genetic defects in - enzymes, - membrane transport proteins (iii) Abnormal control mechanisms (iv) the actions of drugs / toxins.

21. Metabolic reaction: A metabolic reaction is one of the • chemical process • that occur in a living organism • in order to maintain life. • Usually catalyzed by a biocatalyst - enzyme.

22. Metabolic pathway A = Starting material E = End Product B, C, D = Intermediates A series of such chemical reactions make a ‘metabolic pathway’

23. Metabolic pathway maybe • Linear • Branched • Circular Each step involves • transformation of one substance into another • gradually, either breaking down a substance • or building a new chemical substance.

24. Metabolism consists of two processes Metabolism (2 processes) Catabolism Anabolism Energy Energy

25. Catabolism A degradativeprocess which breaks down a complex macromolecule to a smaller molecule with the release of energy. Catabolism Energy • Reactions of Catabolism - catabolic pathway. • Eg: Breakdown of glucose to pyruvate / lactic acid

26. Anabolism A process which forms the complex molecule from small molecules with the expenditure of energy. -constructs components of cells such as carbohydrates, lipids, proteins and nucleic acids. • Reactions of anabolism - anabolic pathway. • Eg: Synthesis of glycogen from glucose; • Fatty acids + glycerol to Triglycerides

27. Amphibolic pathway • A pathway which has dual function, both catabolic and anabolic. Ex: TCA Cycle.

28. Stages Of Energy Metabolism(catabolism)

29. proteins fats carbohydrates 1st stage- digestion and absorption food Simple sugars(mainly glucose), fatty acids ,amino acids ABSORBED AND ENTER 2ND STAGE

30. 2ND STAGE: Products of 1st stage are further broken down to smaller and smaller molecules, and ultimately form a 2 carbon compound called ACETYL CoA Simple sugars(mainly glucose), fatty acids ,amino acids ACETYL CoA (2C compound)

31. 3rd stage: -Involves further complete oxidation of Acetyl CoA By TCA CYCLE and electron transport chain(ETC) to CO2+H2O with the release of energy. ATP TCA CYCLE CO2 ETC NADH, FADH2

32. Intermediary Metabolism All metabolic reactions, catabolic and anabolic, occurring inside the cell is collectively called as intermediary metabolism The speed of metabolism - metabolic rate

33. Types of metabolic reactions : • Functional group transfer • Electron transfer • Rearrangement • Cleavage • Condensation • Elimination Reactions

34. Four characteristics of metabolic pathways 1. Metabolic pathways are unidirectional Reasons : • Ingestion of food • Excretion of products • Irreversible reactions • Coupled reactions

35. Reverse pathway is different Metabolic pathways are highly exergonic which gives the pathway direction.

36. 2. Every metabolic pathway has a committed step (one of the inital steps) • committed step is Irreversible, highly exergonicreaction • Intermediate it produces continues down the pathway. • Eg. : Phospho fructose kinase is the COMMITTED step of glycolysis.

37. 3. All metabolic pathways are regulated. Substrate / starting material End Product S A B C D E F P E1 E2 E3 E4 E5 E6 E7 • Rate determining step • Controls the metabolic flux of metabolites through the pathway • Often is the first committed step of the pathway.

38. 4. Metabolic pathways in eukaryotes occur is specific cellular locations. Compartmentalization of Metabolic Pathways At two levels (i) Cell (ii) organ level • Cell level : Compartmentalization of metabolic pathways in cellular organelles. • Mitochondrion - Citric acid cycle, oxidative phosphorylation, amino acid catabolism. • Cytosol– Glycolysis, pentose phosphate pathway, fatty acid biosynthesis, gluconeogenesis.

39. Organ level compartmentalization • Seen in mullti-cellular organisms. • Liver is the only organ for metabolism (essentially a metabolic organ). Eg : the liver synthesises glucose from non-carbohydrate precursors to maintain the level of glucose in the blood stream. Adipose tissue is specialized for the storage of TAG

40. Regulation of metabolism: There are multiple levels of metabolic regulation. • Extrinsic control • Intrinsic control • Extrinsic control

41. Neuroendocrine regulation Neuronal signals Release hormone into blood Endocrine signals Act on target organs

42. (i) Neuroendocrine regulation : 1. response to signals from nerve cells (neuronal signals). 2. signals from endocrine glands hormones (endocrine signals) and growth factors . 3. detected by specific receptorson the cell surface – target organs. 4. Signals - transmitted inside the cell by second messenger systemsthat often involves the phosphorylation of proteins.

43. (ii) Concentration of substrate : substrate availability is dependent on I . Ingestion of food. II. Transmembrane concentration ratio of the molecules to be transported. Eg: Lipolysis (adipose tissue) Increased plasma fatty acids Increased uptake by liver , muscle Increased beta oxidation

44. Hormone III. The availbility of membrane transport molecules. • Cells of islets of Langerhans - Hormone Insulin Blood Glucose  Glucose Transporters Glucose Hormone –receptor complex Outer surface receptor Cell membrane inner surface Cytoplasm

45. Hormone • Eg : In Diabetes mellitus, Blood Glucose Increased Hormone Insulin Glucose Transporters Glucose Outer surface receptor Cell membrane inner surface Cytoplasm Decreased glucose transporters on the membrane. Decreased transport of glucose .

46. (iii) Concentration of products : • Eg : decrease in the amount of product by excretion can increase the flux through the pathway to compensate. • Intrinsic control • Enzyme regulation by regulating • (i) the concentration of the enzyme and • (ii) the catalytic activity of the enzyme. (Refer : Enzyme regulation).

47. Experimental Approaches to the Study of Metabolism • Understand metabolic pathways – precursor product relationship. • Sequence of reactions • Mechanism of reaction • Control or regulatory mechanism. Need : To understand the biochemical basis of health and disease.

48. Different approaches to study metabolism • Study of metabolic blocks • By studying organisms with metabolic defects – inborn errors / inherited metabolic disorders of metabolism. • 2. By use of radioisotopes

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