NEET MDS Shorts
203624
BiochemistryFollowing digestion, the products of digestion enter the bloodstream.
These include glucose, amino acids, triacylglycerides packaged into chylomicrons from the intestine, and very low density lipoproteins from the liver.
The hormone of anabolism, insulin, is also elevated because of the signaling of the glucose and amino acids in the blood, which allows release of insulin from the β-cells of the pancreas. Insulin aids the movement of glucose and amino acids into cells. In contrast, all the hormones and energy sources associated with catabolism are decreased in the blood during this time. Long-chain fatty acids and glycerol released by lipolysis from adipocytes are not elevated. Glucagon and epinephrine are not released. The only time glucose levels rise significantly above approximately 80 mM is following a well-balanced meal when glucose is obtained from the diet. The concentration of glucose reaches a peak 30 to 45 minutes after a meal and returns to normal within 2 hours after eating. This response of blood glucose after eating (mimicked by giving 50 g of oral glucose) is the basis for the glucose tolerance test. In the event of insulin deficiency (diabetes mellitus), the peak glucose concentration is abnormally high and its return to normal is delayed.
247090
BiochemistryVitamin 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.
404923
BiochemistryThe rate limiting step in glycolysis is catalyzed by Phosphofructokinase
362578
BiochemistryEpinephrine, also known as adrenaline, is a hormone and neurotransmitter that
is synthesized in the body from the amino acid tyrosine. Tyrosine is a
non-essential amino acid, which means that it can be synthesized in the body
from phenylalanine, another essential amino acid. The synthesis of epinephrine
occurs in two main steps:
1. Hydroxylation of tyrosine: Tyrosine is converted into dihydroxyphenylalanine
(DOPA) by the enzyme tyrosine hydroxylase. This is the rate-limiting step in the
synthesis of epinephrine.
2. Decarboxylation and further hydroxylation: DOPA is then decarboxylated to
form dopamine, which is further hydroxylated to produce norepinephrine.
Norepinephrine is the immediate precursor of epinephrine.
3. Formation of epinephrine: Norepinephrine is methylated by the enzyme
phenylethanolamine N-methyltransferase (PNMT) and converted into epinephrine.
The other amino acids listed are not directly involved in the synthesis of
epinephrine:
1. Valine and Leucine are branched-chain amino acids that are primarily involved
in the metabolism of muscles and energy production.
2. Cysteine is a sulfur-containing amino acid that is important for the
synthesis of proteins with disulfide bridges and is a precursor for other
molecules like glutathione and taurine, but not directly involved in the
synthesis of epinephrine.
583515
BiochemistryGlutamate-pyruvate trans-aminase is predominantly present In Liver
625069
Biochemistryâ-oxidation of fatty acid occursin Mitochondria
349170
BiochemistryThe correct sulfur-containing amino acid among the options provided is:
1. Cystine
Explanation:
Amino acids are the building blocks of proteins, and they are characterized by
the presence of an amino group (-NH2) and a carboxyl group (-COOH). Some amino
acids also contain a side chain that is unique to each amino acid and determines
its chemical properties. Sulfur is an important element in the structure and
function of certain amino acids.
Cystine is a sulfur-containing amino acid, which is formed by the oxidation of
two cysteine molecules. Cysteine is the amino acid that contains a sulfur atom
in its side chain as a thiol group (-SH). When two cysteine residues are
adjacent in a polypeptide chain and the thiol groups react with each other, they
form a disulfide bond (-S-S-), resulting in the formation of cystine. This
disulfide bond is crucial for the tertiary structure of proteins, contributing
to their stability and function, particularly in the context of protein folding
and maintaining the integrity of protein domains.
The other options listed are not sulfur-containing amino acids:
2. Proline is an imino acid, meaning it contains an -NH group instead of an -NH2
group. Its side chain is a cyclic secondary amine and does not contain sulfur.
3. Arginine is a basic amino acid with a guanidino group in its side chain,
which is composed of nitrogen, carbon, and hydrogen atoms but no sulfur.
4. Isoleucine is a branched-chain amino acid, with a methyl group and an
isobutyl group on its side chain. It is a hydrophobic amino acid and does not
contain sulfur.
800260
BiochemistryThe immunoglobulin secreted in Bile is IgA