Examples of amino acid in the following topics:
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Proteins: Sources, Uses in the Body, and Dietary Requirements
- Most microorganisms and plants can biosynthesize all 20 standard amino acids , while animals (including humans) must obtain some of the amino acids from the diet.
- The amino acids that an organism cannot synthesize on its own are referred to as essential amino acids.
- Key enzymes that synthesize certain amino acids are not present in animals.
- In animals, amino acids are obtained through the consumption of foods containing protein .
- Amino acids are also an important dietary source of nitrogen.
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Types of Neurotransmitters by Function
- The major types of neurotransmitters include: acetylcholine, biogenic amines and amino acids.
- Dopamine and NE are synthesized from amino acid tyrosine.
- Histamine is synthesized from amino acid ___.
- Glutamate and gamma - aminobutyric acid (GABA) are amino acid based neurotransmitters.
- Neuropeptides such as Substance P and Endorphins are strings of amino acids that are important in the mediation of pain signals.
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Phenylketonuria (PKU)
- PAH enzyme is necessary for the metabolism of the amino acid phenylalanine (Phe) to the amino acid tyrosine.
- Phenylalanine is a large, neutral amino acid (LNAA).
- LNAAs compete for transport across the blood–brain barrier (BBB) via the large neutral amino acid transporter (LNAAT).
- However, as these amino acids are necessary for protein and neurotransmitter synthesis, Phe buildup hinders the development of the brain, causing mental retardation.
- The mainstream treatment for classic PKU patients is a strict PHE-restricted diet supplemented by a medical formula containing amino acids and other nutrients.
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Absorption of Monosaccharides, Amino Acids, Dipeptides, Tripeptides, Lipids, Electrolytes, Vitamins, and Water
- Glucose, amino acids, fats, and vitamins are absorbed in the small intestine via the action of hormones and electrolytes.
- Proteins are degraded into small peptides and amino acids before absorption.
- Carboxypeptidase, which is a pancreatic brush border enzyme, splits one amino acid at a time.
- Aminopeptidase and dipeptidase free the end amino acid products.
- Lipids (fats) are degraded into fatty acids and glycerol.
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Chemistry of Hormones
- Peptide hormones consist of chains of amino acids (example vasopressin) or longer chains of amino acids (example insulin) .
- Lipid- and phospholipid-derived hormones are produced from lipids such as linoleic acid and arachidonic acid.
- Monoamine hormones are derived from aromatic amino acids like phenylalanine, tyrosine and tryptophan.
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Mechanisms of Chemical Digestion
- ., polysaccharides, proteins, fats, nucleic acids) to smaller ones (i.e., monosaccharides, amino acids, fatty acids, nucleotides) .
- The endopeptidases cleave the polypeptide at the interior peptide bonds, while the exopeptidases cleave the terminal amino acid.
- Exopeptidases are further subclassified into aminopeptidases - which cleave off the terminal amino acid at the amine end of the chain, and carboxypeptidases which cleave off the terminal amino acid at the carboxyl end of the chain.
- Stomach pepsin cleaves interior bonds of the amino acids, and is particularly important for its ability to digest collagen.
- Fats are digested by lipases which hydrolyze the glycerol-fatty acid bonds.
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Absorptive State
- This main product of fat digestion is first broken down to fatty acids and glycerol through hydrolysis using lipoprotein lipase.
- The liver deaminates amino acids to keto acids to be used in the Kreb's cycle in order to generate energy in the form of ATP.
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Digestive Processes of the Small Intestine
- Proteins are degraded into small peptides and amino acids before absorption.
- Carboxypeptidase, a pancreatic brush border enzyme, splits one amino acid at a time.
- Aminopeptidase and dipeptidase free the end amino acid products.
- Lipids (fats) are degraded into fatty acids and glycerol.
- Pancreatic lipase breaks down triglycerides into free fatty acids and monoglycerides.
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Gastric Phase
- The gastric phase is a period in which swallowed food and semidigested protein (peptides and amino acids) activate gastric activity.
- All three of these stimulate parietal cells to secrete hydrochloric acid and intrinsic factor.
- As dietary protein is digested, it breaks down into smaller peptides and amino acids, which directly stimulate the G cells to secrete even more gastrin: a positive feedback loop that accelerates protein digestion.
- Small peptides also buffer stomach acid so the pH does not fall excessively low.
- Below pH of two, stomach acid inhibits the parietal cells and G cells: a negative feedback loop that winds down the gastric phase as the need for pepsin and HCl declines.
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Carbohydrates: Sources, Uses in the Body, and Dietary Requirements
- Humans can synthesize some glucose (in a set of processes known as "gluconeogenesis") from specific amino acids or from the glycerol backbone in triglycerides and, in some cases, from fatty acids.
- In the case of protein, this is somewhat misleading as only some amino acids are able to undergo conversion into useful energy forms.