NEET MDS Shorts
41719
BiochemistryVitamin C deficiency is due to defect of Lysyl hydroxylase
83015
Biochemistry
Vitamin D is crucial for the maintenance of bone health as it aids in the
absorption of calcium from the digestive tract and facilitates the incorporation
of calcium into bones. A deficiency in vitamin D can lead to osteoporosis, a
condition characterized by weak and porous bones that are more susceptible to
fractures, which is common in the elderly. While vitamin A (Answer 1) is
important for vision and skin health, and niacin (Answer 2) and thiamine (Answer
3) have roles in energy metabolism and nerve function, respectively, vitamin D's
primary role in calcium homeostasis makes it most relevant to bone loss in older
individuals.
36542
Biochemistry
Uric acid is a purine derivative, increased by purine salvage reactions that convert purines, purine ribonucleosides, and purine deoxyribonucleoside to mononucleotides (incorrect answer 4). A defect in hypoxanthine-guanine phosphoribosyl transferase, one of the enzymes of purine salvage, is responsible for purine overproduction and subsequent hyperuricemia observed in Lesch-Nyhan syndrome.
Such salvage reactions require much less energy than de novo synthesis (incorrect answers 1, 2). The liver is the major site of purine nucleotide biosynthesis and provides excess purines for other tissues that cannot synthesize purines.
29486
BiochemistryVLDL is a lipoprotein particle synthesized in the liver and secreted into the bloodstream to transport endogenously synthesized triglycerides and cholesterol to peripheral tissues. The triglycerides in VLDL are derived from fatty acids synthesized in the liver, and the cholesterol is derived from both dietary sources and de novo synthesis in the liver. They are not usually linked covalently to apoproteins (Answer 1), nor do they primarily consist of phosphatidylcholine (Answer 2). While the types of lipids found in the diet (Answer 4) can influence the liver's synthesis of VLDL, the statement does not accurately describe the direct composition of VLDL.
93915
Biochemistry
The enzyme phosphatidate phosphatase converts phosphatidic acid to diacylglycerol during synthesis of triacylglycerides. The function of adipose tissue is the storage of fatty acids as triacylglycerols in times of plenty and the release of fatty acids during times of fasting or starvation. Fatty acids taken in by adipocytes are stored by esterification to glycerol-3-phosphate. Glycerol-3-phosphate is derived almost entirely from the glycolytic intermediate dihydroxyacetone phosphate through the action of glycerol-3-phosphate dehydrogenase. Glycolytic enzymes are active in adipocytes during triglyceride synthesis, but those of glycogen degradation (low levels in adipocytes) and gluconeogenesis (ie, glucose-6-phosphatase) are not. Glycerol kinase is not present to any great extent in adipocytes, so that glycerol freed during lipolysis is not used to reesterify the fatty acids being released. The enzyme triacylglyceride lipase is turned on by phosphorylation by a cyclic AMP-dependent protein kinase following epinephrine stimulation.
42310
BiochemistryRate limiting step of Kreb's cycle is catalysed by isocitrate dehydrogenase
45163
Biochemistry
Glycolysis is a metabolic process that occurs in the cytoplasm of the cell.
The process is central to the conversion of glucose into energy in the form of
adenosine triphosphate (ATP) and is a fundamental part of cellular respiration.
1. Cytoplasm: Glycolysis takes place in the cytoplasm of the cell. The cytoplasm
is the fluid-filled space between the cell membrane and the nucleus (and other
organelles in eukaryotes) where various metabolic reactions occur. This process
involves a series of enzymatic reactions that break down one molecule of glucose
into two molecules of pyruvate, yielding two net molecules of ATP and two
molecules of NADH (a reduced form of nicotinamide adenine dinucleotide) along
with some other byproducts.
2. Mitochondrion: Although glycolysis does not occur in the mitochondrion, the
mitochondrion plays a crucial role in the subsequent stages of glucose
metabolism. After glycolysis, the pyruvate molecules produced in the cytoplasm
can be transported into the mitochondria, where they are further processed in
the citric acid cycle (also known as the Krebs cycle or TCA cycle) and the
electron transport chain to produce more ATP.
57919
BiochemistryThe formation of oxyhemoglobin is influenced by 1. pH 2. CO2 concentration 3. Temperature
93900
BiochemistryAcetylcholinesterase receptor opens an ion channel, undergoes irreversible conformational changes when exposed to carbamates , it is inactivated in myasthenia gravis
21978
Biochemistry
Enzymes are biological catalysts that increase the rate of chemical reactions
by lowering the activation energy required for the reaction to occur.