All Important Things About Carbohydrate Metabolism - NEET PG Biochemistry
Feb 13, 2023
Carbohydrate metabolism is an important topic for the NEET PG exam because it is a fundamental aspect of human physiology and biochemistry. It plays a crucial role in the pathophysiology of various diseases such as diabetes, obesity, and metabolic syndrome. A deep understanding of the mechanisms involved in carbohydrate metabolism is essential for the diagnosis, treatment, and management of these conditions.
Additionally, the NEET PG exam is a comprehensive test that covers all aspects of medical science, and carbohydrate metabolism is a fundamental topic that is tested in biochemistry and endocrinology. Hence, a strong understanding of the topic is crucial for success in the NEET PG exam.
In this blog post, we’ll be covering important details pertaining to this topics. Read on.
Energy status of cell. If energy is present, TCA will not occur & vice-versa.
Availability of oxaloacetate. Thus, oxaloacetate is also regarded as carrier of TCA cycle or 1st Substrate of TCA cycle. Also, it plays a catalytic role in TCA cycle.
Only occurs in aerobic state
Not occurs in anaerobic state due to feedback regulation by NADH & FADH2 which are unable to enter ETC as O2 is absent.
Only 1 SLP occurs in TCA done by enzyme succinate thiokinase which mostly produces ATP but in liver & kidney during fasting/starvation state, it produces GTP as during this state, gluconeogenesis occurs & it requires GTP.
Acetyl CoA is not an intermediate of TCA cycle
2 CO2 which are removed in TCA comes from Oxaloacetate. If oxaloacetate not given, then mark acetyl CoA
Inhibitors of TCA
Malate (4C): Intermediate of TCA Cycle
Malonate (3C): Inhibitor of TCA Cycle
Malonate / Malonyl CoA is an inhibitor of
TCA Cycle (Enz inhibited is Succinate Dehydrogenase)
ETC (component inhibited is Complex II)
Beta Oxidation of Fatty Acids (Enz inhibited is CPT-1)
5 coenzymes are required for link reaction & TCA: Lipoic acid, B1, B2, B3,B5.
Lethargy (low energy) is mostly diagnosed due to low levels of these vitamins and multivitamins supplementations are recommended as a remedy
G6PD deficiency→↓NADPH production in RBC →↓reduced glutathione →↑H2O2 → cause cell
membrane lysis and hemolysis
Aldose reductase generally present in all cells
Sorbitol dehydrogenase present only in liver and testis (as fructose is main energy source for sperms)
Clinical significance of polyol pathway:
In patient with uncontrolled diabetes, excess blood glucose enters insulin-insensitive tissues such as peripheral nerves, renal glomeruli, lens and retina and leads to the formation of excess sorbitol by aldose reductase. But sorbitol dehydrogenase is absent in most of these cells and sorbitol cannot be converted to fructose. Hence, sorbitol accumulation occurs.
Sorbitol is hygroscopic and will absorb water causing cell swelling ultimately leading to complications such as retinopathy, neuropathy, nephropathy and also snow-flake cataract in diabetic patients.
Q. All are features of gluconeogenesis except?(JIPMER Dec 2019)
Gluconeogenesis is synthesis of glucose from non-carbohydrate source
Mainly takes place in liver
Seen in fasting state
Step are simple reversal of glycolysis
Q. Glucose is stored in Glycogen form, why? (AIIMS June 2020)
Can be reduced from multiple branches lends
Can be stored ale multiple Sites
Can provide glucose an muchas needed and when needed for 1 week
Q. Complex IV in Election Transport chain is inhibited by? (FMGE Dec 2020)
Q. Enzymes used in gluconeogenesis are? (INICET Nov 2020)
Q. Enzyme present in both glycolysis and gluconeogenesis? (AIIMS June 2020)
Q. Cytochrome C oxidase is inhibited by all EXCEPT?(INICET July 2021)
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