AMINO ACIDS

INTRODUCTION: Proteins occur in every living organism, are of many different types, and have many different biological functions. The keratin of skin and fingernails, the spider webs, and the estimated 50,000 or so enzymes that catalyze the biological reactions in our bodies are all proteins. Regardless of their function, all proteins have a fundamentally similar structure and are made up of many amino acids linked together in a long chain.

AMINO ACIDS AS BUILDING BLOCKS OF PROTEINS: Amino acids, as their name implies, are difunctional. They contain both a basic amino group and an acidic carboxyl group. Their value as building blocks to make proteins stems from the fact that amino acids can join together into long chains by forming amide bonds between the NH2 of one amino acid and the CO2H of another. For classification purposes, chains with fewer than 50 amino acids are often called peptides, while the term protein is generally used for larger chains.

AMINO ACIDS AND ACID-BASE BALANCE: Because amino acids contain both basic amino and acidic carboxyl groups, they undergo an intramolecular acid–base reaction and exist in aqueous solution primarily in the form of dipolar ions, called zwitterions. Amino acid zwitterions are internal salts and therefore have many of the physical properties associated with salts. They are relatively soluble in water but insoluble in hydrocarbons and are crystalline substances with relatively high melting points. In addition, amino acids are amphiprotic, meaning that they can react either as acids or as bases, depending on the circumstances. 

EXCHANGE OF IONS BETWEEN AMINO ACIDS: In aqueous acid solution, an amino acid zwitterion is a base that accepts a proton onto its CO2 group to yield a cation; in aqueous base solution, the zwitterion is an acid that loses a proton from its NH3 group to form an anion.

RELATED

1.  PROTEINS

2.  DIVERSITY OF BIOMOLECULES

3.  NUCLEIC ACIDS

4.  FATTY ACIDS

REFERENCES

POLYSACCHARIDES

 

INTRODUCTION: These are polymerized products of many monosaccharide units. They may be;

1) Homoglycans, which are composed of single kind of monosaccharides such as, starch, glycogen and cellulose.

2. Heteroglycans, which are composed of two or more different monosaccharides, hyaluronic acid, chondroitin sulphate.

STARCH: It is the reserve carbohydrate of plant kingdom. Common sources include; Potatoes, tapioca, cereals such as rice, wheat, and other food grains. Starch is composed of amylose and amylopectin. When starch is treated with boiling water, 10-20% is solubilized; this part is called amylose. Amylose is made up of glucose units with alpha-1,4 glycosidic linkages to form an unbranched long chain with a molecular weight 400,000 D or more.

The insoluble part absorbs water and forms paste like gel and this is called amylopectin. Amylopectin is also made up of glucose units, but is highly branched with molecular weight more than 1 million. The branching points are made by alpha-1,6 linkage.

HYDROLYSIS OF STARCH: Starch will form a blue colored complex with iodine; this color disappears on heating and reappears when cooled. This is a sensitive test for starch. Starch is non reducing because the free sugar groups are negligible in number. When starch is hydrolysed by mild acid, smaller and smaller fragments are produced. Thus hydrolysis for a short time produces amylodextrin which gives violet color with iodine and is non-reducing. Further hydrolysis produces erythrodextrin which gives red color with iodine and mild reduction of Benedict's solution. Later achrodextrins with no color with iodine, but reducing, and further on, maltose with no color with iodine, but powerfully reducing, are formed on continued hydrolysis.

ACTION OF AMYLASES ON STARCH: Salivary amylase and pancreatic amylase are alpha-amylases, which act at random on alpha 1,4-glycosidic bonds to split starch into smaller units also known as dextrins, and finally to alpha-maltose.

Beta-amylases are of plant origin including almond, germinating seeds, which split starch to form beta-maltose. They act on amylose to split maltose units consecutively. Thus the enzyme starts its action from one end. When beta-amylase acts on amylopectin, maltose units are liberated from the ends of the branches of amylopectin, until the action of enzyme is blocked at the 1,6-glycosidic linkage. The action of beta-amylase stops at branching points, leaving a large molecule, called limit dextrin or residual dextrin.

GLYCOGEN: It is the reserve carbohydrate in animals. It is stored in liver and muscle. About 5% of weight of liver is made up by glycogen. Excess carbohydrates are deposited as glycogen. Glycogen is composed of glucose units joined by alpha-1,4 links in the straight chains. It also has alpha-1,6 glycosidic linkages at the branching points. Molecular weight of glycogen is about 5 million. Innermost core of glycogen contains a primer protein, Glycogenin. Glycogen is more branched and more compact than amylopectin.

CELLULOSE: It is the supporting tissues of plants. Cellulose constitutes 99% of cotton, 50% of wood and is the most abundant organic material in nature. It is made up of glucose units combined with beta-1,4 linkages. It has a straight line structure, with no branching points. Molecular weight is in the order of 2 to 5 million. Beta-1,4 bridges are hydrolysed by the enzyme cellobiase. But this enzyme is absent in animal and human digestive system, and hence cellulose cannot be digested. Herbivorous animals have large caecum, which harbor bacteria. These bacteria can hydrolyse cellulose, and the glucose produced is utilized by the animal. White ants also known as termites also digest cellulose with the help of intestinal bacteria. Cellulose has a variety of commercial applications, as it is the starting material to produce fibres, celluloids, nitrocellulose and plastics.

INULIN: It is a long chain homoglycan composed of D-fructose units with repeating beta-1,2 linkages. It is the reserve carbohydrate present in various bulbs and tubers such as chicory, dahlia, dandelion, onion, garlic. It is clinically used to find renal clearance value and glomerular filtration rate.

DEXTRANS: These are highly branched homopolymers of glucose units with 1-6, 1-4 and 1-3 linkages. They are produced by microorganisms. They have molecular weight 1 million to 4 millions. Since they will not easily go out of vascular compartment, they are used for intravenous infusion as plasma volume expander for treatment of hypovolemic shock.

CHITIN: It is present in exoskeletons of crustacea and insects. It is composed of units of N-acetylglucosamine with beta-1,4 glycosidic linkages.

HETEROGLYCANS: These are polysaccharides containing more than one type of sugar residues. Examples are: Agar which is prepared from sea weeds. It contains galactose, glucose and other sugars. It is dissolved in water at 100° C, which upon cooling sets into a gel. Agar cannot be digested by bacteria and hence used widely as a supporting agent to culture bacterial colonies. Agar is used as a supporting medium for immuno-diffusion and immuno-electrophoresis.

Agarose is made up of galactose combined with 3,6-anhydrogalactose units; it is used as matrix for electrophoresis.

RELATED;

1. STARCH

2. GLYCOGEN

3. CELLULOSE

4. THE GLYCOSIDIC BOND

5. PLASMA VOLUME EXPANDERS

REFERENCES

DISACCHARIDES

 

INTRODUCTION: When two monosaccharides are combined together by glycosidic linkage, a disaccharide is formed. The important disaccharides are; 1) Sucrose 2) Maltose and isomaltose 3) Lactose.

SUCROSE: It is the sweetening agent known as cane sugar, present in sugarcane and various fruits. Sucrose contains glucose and fructose. Sucrose is not a reducing sugar; and it will not form osazone. This is because the linkage involves first carbon of glucose and second carbon of fructose, and free reducing groups are not available. When sucrose is hydrolysed, the products have reducing action. During laboratory investigations, a sugar solution which is originally non-reducing then becomes reducing after hydrolysis, and is identified as sucrose. This serves as the specific sucrose test.

LACTOSE: It is the sugar present in milk. It is a reducing disaccharide. On hydrolysis lactose yields glucose and galactose. Beta glycosidic linkage is present in lactose. The anomeric carbon atom of beta-galactose is attached to the 4th hydroxyl group of glucose through beta-1,4 glycosidic linkage. The lactose may be alpha or beta variety, depending on the configuration of 1st carbon of glucose moiety.

MALTOSE: Maltose contains two glucose residues. There is alpha-1,4 linkage, that is to say, the anomeric 1^st carbon atom of one glucose is combined with 4^th hydroxyl group of another glucose through alpha-glycosidic linkage. Maltose may be alpha or beta depending on the configuration at the free anomeric carbon atom. It is a reducing disaccharide. Isomaltose It is also a reducing sugar. It contains 2 glucose units combined in alpha -1, 6 linkage. Thus first carbon of one glucose residue is attached to the sixth carbon of another glucose through a glycosidic linkage. Partial hydrolysis of glycogen and starch produces isomaltose. The enzyme oligo1,6-glucosidase present in intestinal juice can hydrolyse isomaltose into glucose units.

RELATED;

1. THE GLYCOSIDIC BOND

2. LACTOSE INTOLERANCE

3. CARBOHYDRATES

REFERENCES

VITAMIN A

 

Therapeutic Class: Lipid-soluble vitamin

Pharmacologic Class: Retinoid

ACTIONS AND USES: Vitamin A is essential for general growth and development, particularly of the bones, teeth, and epithelial membranes. It is necessary for proper wound healing, is essential for the biosynthesis of steroids, and is one of the pigments required for night vision. Wound healing

Vitamin A is indicated in deficiency states and during periods of increased need such as pregnancy, lactation, or undernutrition. Night blindness and slow wound healing can be effectively treated with as little as 30,000 units of vitamin A given daily over a week. It is also prescribed for GI disorders, when absorption in the small intestine is diminished or absent. Topical forms are available for acne, psoriasis, and other skin disorders. Doses of vitamin A are sometimes measured in retinoid equivalents (RE). In severe deficiency states, up to 500,000 units may be given per day for 3 days, gradually tapering off to 10,000–20,000 units/day.

ADMINISTRATION ALERTS: Pregnancy category A, at low doses. Pregnancy category X, at doses above the RDA. [Read about drug use in relation to pregnancy]

ADVERSE EFFECTS: Adverse effects are not observed with normal doses of vitamin A. Acute ingestion, however, produces serious central nervous system (CNS) toxicity, including headache, irritability, drowsiness, delirium, and possible coma. Long-term ingestion of high amounts causes drying and scaling of the skin, alopecia, fatigue, anorexia, vomiting, and leukopenia.

CONTRAINDICATIONS: Vitamin A in excess of the RDA is contraindicated in pregnant patients, or those who may become pregnant. Fetal harm may result.

INTERACTIONS: Drug–Drug: People who are taking vitamin A should avoid taking mineral oil and cholestyramine, because both may decrease the absorption of vitamin A. Concurrent use with isoretinoin may result in additive toxicity.

LAB TESTS: Vitamin A may increase serum calcium, serum cholesterol, and blood urea nitrogen (BUN).

RELATED;

1.  VITAMIN C  

2.  BIOMOLECULES  

3.  ALBUM OF BIOCHEMISTRY

4.  BIOCHEMISTRY

REFERENCES

NITRIC OXIDE

INTRODUCTION: Nitric oxide is a gas with the molecular formula NO. You have probably heard of it as a component of air pollution and cigarette smoke, but it is synthesized by several human tissues, and this deceptively simple molecule has important functions. Nitric oxide is produced by the endothelium (lining) of blood vessels and promotes vasodilation of arterioles, permitting greater blood flow and oxygen delivery to tissues. It is involved in nerve impulse transmission in the brain, and may contribute to memory storage. Some immune system cells produce nitric oxide as a cytotoxic (cell-poisoning) agent to help destroy foreign cells such as bacteria.

CLINICAL APPLICATIONS: Nitric oxide is also being used therapeutically in clinical trials. It has been found useful in the treatment of pulmonary hypertension to relax abnormally constricted arteries in the lungs to permit normal gas exchange. Other studies show that nitric oxide helps some premature babies breathe more easily and efficiently. Much more research is needed, including a determination of possible harmful side effects of greater than normal amounts of nitric oxide, but the results of some clinical trials thus far are promising.

RELATED;

1. OXYGEN  

2. CARBON DIOXIDE

3.  BIOCHEMISTRY

REFERENCES

HEMOGLOBIN

 

Introduction:  Red blood cells (RBC) are biconcave discs, with a diameter of about 7 microns.  RBCs live for about 120 days in peripheral circulation, during which time they traverse about 160 km across the human body.  In a 70 Kg person, there will be about 25 x 1012 RBCs and 750g of hemoglobin (Hb).  100 ml blood contains about 14.5g of Hb.  Mature RBC is non-nucleated; have no mitochondria and does not contain TCA cycle enzymes.  However, the glycolytic pathway is active which provides energy and 2,3-bisphosphoglycerate (2,3-BPG).  [METABOLISM AND METABOLIC DISORDERS]

Origin of hemoglobin:  Human erythropoietin, a glycoprotein with molecular weight of 34 kD, is the major stimulator of erythropoiesis,  a procees that lead to synthesis and production of hemoglobin.  It is synthesized in kidney and is released in response to hypoxia.  RBC formation in the bone marrow requires amino acids, iron, copper, folic acid, vitamin B12, vitamin C, pyridoxal phosphate and pantothenic acid; they are used as hematinics in clinical practice.  [RED BLOOD CELLLS]

Structural components of heme:  Hemoglobin is a conjugated protein having heme as the prosthetic group and the protein, the globin. It is a tetrameric protein with 4 subunits, each subunit having a prosthetic heme group and the globin polypeptide.  The polypeptide chains are usually two alpha and two beta chains. Hemoglobin has a molecular weight of about 67,000 Daltons.  Each gram of Hb contains 3.4 mg of iron.  Heme is present in a) Hemoglobin b) Myoglobin c) Cytochromes d) Peroxidase e) Catalase f) Tryptophan pyrrolase g) Nitric oxide synthase.  Heme is produced by the combination of iron with a porphyrin ring.  Chlorophyll, the photosynthetic green pigment in plants is magnesium-porphyrin complex.

RELATED;

1.  RED BLOOD CELLS  

2.  ANAEMIA

3.  ANATOMY AND PHYSIOLOGY

[REFERENCES]

HUMAN ENZYMES AND THEIR SUBSTRATES

HUMAN ENZYMES AND THEIR SUBSTRATES:  Metabolic processes in the human body specifically in the gastrointestinal tract, depends on enzymatic actions.  The breakdown of food components that we take in in most cases is in complex forms and in order for it to be assimilated, it must be broken down into simpler and absorbable monomers.

1.  Lactase:  This enzyme is responsible for breakdown of lactose chiefly present in milk, and present in the gastrointestinal tract.  Lactose is a disaccharide containing two monosaccharides galactose and glucose.  A deficiency in this enzyme causes a condition known as lactose intolerance discussed earlier and if you would like to read bout it, you can click on the link below.

Lactose intolerance

RELATED;

1.  BIOCHEMISTRY OF ENZYMES

2.  CO-ENZYMES

3.   LACTOSE INTOLERANCE

STARCH

 

STRUCTURE OF STARCH:  It is the reserve carbohydrate of plant kingdom.  The most common sources of starch include but not limited to; Potatoes, tapioca, cereals including rice and wheat, and other food grains.  Starch is composed of amylose and amylopectin.  When starch is treated with boiling water, 10-20% is solubilized; this part is called amylose.  Amylose is made up of glucose units with alpha-1,4 glycosidic linkages to form an unbranched long chain with a molecular weight 400,000 D or more.  The insoluble part absorbs water and forms paste like gel and this is called amylopectin.  Amylopectin is also made up of glucose units, but is highly branched with molecular weight more than 1 million.  The branching points are made by alpha-1,6 linkage similar to isomaltose.

HYDROLYSIS OF STARCH:  Starch will form a blue colored complex with iodine; this color disappears on heating and reappears when cooled.  This is a sensitive test for starch.   Starch is non reducing because the free sugar groups are negligible in number.  When starch is hydrolysed by mild acid, smaller and smaller fragments are produced.  Thus hydrolysis for a short time produces amylodextrin which gives violet color with iodine and is nonreducing.  Further hydrolysis produces erythrodextrin which gives red color with iodine and mild reduction of Benedict's solution.  Later achrodextrins (no color with iodine, but reducing) and further on, maltose (no color with iodine, but powerfully reducing) are formed on continued hydrolysis.

ACTION OF AMYLASES ON STARCH:  Salivary amylase and pancreatic amylase are alpha-amylases, which act at random on alpha1,4 glycosidic bonds to split starch into smaller units (dextrins), and finally to alpha-maltose.  Beta-amylases are of plant origin (almond, germinating seeds, etc) which split starch to form beta-maltose.  They act on amylose to split maltose units consecutively.  Thus the enzyme starts its action from one end.  When beta-amylase acts on amylopectin, maltose units are liberated from the ends of the branches of amylopectin, until the action of enzyme is blocked at the 1,6-glycosidic linkage. The action of beta-amylase stops at branching points, leaving a large molecule, called limit dextrin or residual dextrin.

RELATED;

1.  CARBOHYDRATES

2.  DISACCHARIDES

CHOLESTEROL AND THE HUMAN BODY

INTRODUCTION: Almost all nucleated cells including arterial walls can synthesise cholesterol. It is widely distributed in the body. In a 70 kg man, a total of about 140g of cholesterol is available; which is roughly distributed as 30g in brain and nerves, 30g in muscles, 30 g in adipose tissue, 20g in skin, 10g in blood, 10g in liver and spleen, 5g in bone marrow, 3g in alimentary tract, and 2g in adrenal gland. Cholesterol is a light yellow crystalline solid. When the crystals are examined under the microscope, they show a notched appearance. Cholesterol is soluble in chloroform and other fat solvents. It is the most important animal steroid from which other steroid compounds are formed. Cholesterol is widely distributed in animal tissues. It is absent in prokaryotes. In plants, cholesterol is absent, but other plant sterols are present. In bacteria and plants, compounds similar to steroids exist, known as hopanoids.

CLINICAL SIGNIFICANCE OF CHOLESTEROL: The level of cholesterol in blood is related to the development of atherosclerosis and myocardial infarction.

FUNCTIONS OF CHOLESTEROL

1. Cell membranes: Cholesterol is a component of membranes and has a modulating effect on the fluid state of the membrane. Theplasma membrane

2. Nerve conduction: Cholesterol has an insulating effect on nerve fibers.

3. Bile acids and bile salts are derived from cholesterol. Bile salts are important for fat absorption.

4. Steroid hormones: Glucocorticoids, androgens and estrogens are from cholesterol.

5. Vitamin D3 is from 7-dehydro-cholesterol.

6. Esterification: The OH group of cholesterol is esterified to fatty acids to form cholesterol esters.

ABSORPTION OF CHOLESTEROL: Cholesterol ester present in the diet is hydrolysed by cholesterol-esterase. The free cholesterol is incorporated into bile salt micelle and absorbed into the mucosal cell. Absorption needs micellar formation. There is a specific protein which facilitates the transport of cholesterol into the mucosal cell from the micelle. Inside the mucosal cell, cholesterol is re-esterified and incorporated into chylomicrons. The chylomicrons reach the bloodstream through lymphatics. This dietary cholesterol reaches the liver through chylomicron remnants.

BIOSYNTHESIS OF CHOLESTEROL: All carbon atoms of cholesterol are derived from acetyl CoA. The major sites of synthesis of cholesterol are liver, adrenal cortex, testes, ovaries and intestine. All nucleated cells can synthesise cholesterol, including arterial walls. The enzymes involved in the synthesis of cholesterol are partly located in the endoplasmic reticulum and partly in the cytoplasm.

REGULATION OF CHOLESTEROL SYNTHESIS

1. Regulation at transcription: The regulatory enzyme is HMG CoA reductase. Long-term regulation involves regulation of transcription of the gene for HMG CoA reductase. When sufficient cholesterol is present in the cell, transcription of the gene for HMG CoA reductase is suppressed, and cellular synthesis of cholesterol is decreased. When cholesterol in diet is low, synthesis is increased.  

2. Cholesterol regulates the expression of HMG CoA reductase gene and LDLR (LDL receptor) gene. A specific recognition sequence known as the sterol regulatory element (SRE) is present in DNA. SRE binding by sterol regulatory element binding protein (SREBP) is essential for the transcription of these genes. When cholesterol levels are sufficiently high, the SREBP remains as an inactive precursor. The SREBP cleavage activator protein (SCAP), is an intracellular cholesterol sensor. When cholesterol is less, SCAP escorts SREBP to Golgi bodies. Two Golgi proteases (S1P and S2P) sequentially cleave the SREBP to a protein which binds to SRE and activates transcription of HMG CoA reductase gene.  

3. Covalent modification: Short-term regulation is by covalent modification of the enzyme. Cyclic AMP mediated cascade phosphorylates the enzyme which is inactive. Dephosphorylated form is active. Further, the activity of HMG CoA reductase is also regulated by the rate of degradation of enzyme protein.  

4. Insulin and thyroxine increase the activity of HMG CoA reductase.  

5. Cortisol and glucagon decrease its activity.  

6. Drugs: Lovastatin and other "statin" group of drugs are competitive inhibitors of HMG CoA reductase. So, they are used in clinical practice to reduce cholesterol level in blood.

CHOLESTEROL POOL AND CHOLESTEROL METABOLISM: The total body cholesterol content varies from 130-150 grams. LDL (low density lipoprotein) transports cholesterol from the liver to the peripheral tissues and HDL (high density lipoprotein) transports cholesterol from tissues to liver. Cells of extrahepatic tissues take up cholesterol from LDL. The free cholesterol released within the cell has the following fates:  

1. Incorporated into cell membranes.  

2. Metabolised to steroid hormones, especially in adrenal cortex and gonads. 

3. Esterified with saturated fatty acids and stored in the cell. The enzyme ACAT (acyl cholesterol acyl transferase) helps in this reaction. 

4. Esterified with poly-unsaturated fatty acids (PUFA) by the action of LCAT (lecithin cholesterol acyl transferase) and incorporated into HDL, transported and finally excreted through liver.

EXCRETION OF CHOLESTEROL: Average diet contains about 300 mg of cholesterol per day. Body synthesizes about 700 mg of cholesterol per day. Out of this total 1000 mg, about 500 mg of cholesterol is excreted through bile. This cholesterol is partly reabsorbed from intestines. Vegetables contain plant sterols which inhibit the re-absorption of cholesterol. The unabsorbed portion is acted upon by intestinal bacteria to form cholestanol and coprostanol. These are excreted (fecal sterols). Another 500 mg of cholesterol is converted to bile acids, which are excreted in the bile as bile salts.

LIVER AND CHOLESTEROL: The liver has a major role in controlling the plasma levels of LDL cholesterol.  

1. Liver synthesises cholesterol  

2. Liver removes cholesterol from Lp remnants.  

3. Liver is the only organ that can excrete cholesterol through bile.  

4. Liver converts cholesterol to bile acids.

RELATED;

1.  THE PLASMA MEMBRANE

REFERENCES

CALCITRIOL

Therapeutic Class: Vitamin D

Pharmacologic Class: Bone resorption inhibitor 

ACTIONS AND USES: Calcitriol is the active form of vitamin D. It promotes the intestinal absorption of calcium and elevates serum levels of calcium. This medication is indicated for patients with chronic kidney disease or hypoparathyroidism. Calcitriol reduces bone resorption and is used off-label to treat rickets. The effectiveness of calcitriol depends on an adequate amount of calcium; therefore, it is usually prescribed in combination with calcium supplements. It is available as oral tablets and solutions and by the IV route.

ADMINISTRATION ALERTS: Protect capsules from light and heat. Pregnancy category C.

ADVERSE EFFECTS: Vitamin D therapy may cause symptoms of hypercalcemia. These include palpitations, anorexia, nausea, vomiting, blurred vision, photophobia, constipation abdominal cramps, metallic taste, headache, weakness, dry mouth, thirst, increased urination, and muscle or bone pain.

CONTRAINDICATIONS: This drug should not be given to patients with hypercalcemia or with evidence of vitamin D toxicity.

INTERACTIONS:

Drug–Drug: Thiazide diuretics may enhance the effects of vitamin D, causing hypercalcemia. Too much vitamin D may cause dysrhythmias in patients who are receiving digoxin. Magnesium antacids or supplements should not be given concurrently due to the increased risk of hypermagnesemia.

RELATED;

1.  VITAMIN A

2.  CO-ENZYMES

3.  VITAMIN C

REFERENCES

LIPIDS

INTRODUCTION: Lipids contain the elements carbon, hydrogen, and oxygen; some also contain phosphorus. In this group of organic compounds are different types of substances with very different functions. In our discussion here, we will consider three types: true fats, phospholipids, and steroids.

True fats also called neutral fats, are made of one molecule of glycerol and one, two, or three fatty acid molecules. If three fatty acid molecules are bonded to a single glycerol, a triglyceride is formed. Two fatty acids and a glycerol form a diglyceride, and one fatty acid and a glycerol form a monoglyceride.

THE EXTENT AND DEGREE OF BONDING IN FATTY ACIDS: It should also be noted that, the fatty acids in a true fat may be saturated or unsaturated. This is where one of the fatty acids has single covalent bonds between all its carbon atoms. Each of these carbons is then bonded to the maximum number of hydrogens; this is a saturated fatty acid, meaning saturated with hydrogen. On the other hand, a fatty acids may have one or more (poly) double covalent bonds between their carbons and less than the maximum number of hydrogens; these are then termed unsaturated fatty acids. Many triglycerides contain both saturated and unsaturated fatty acids.

DISTINCT APPEARANCE OF FATS: At room temperature, saturated fats are often in solid form, while unsaturated fats are often in liquid form. Saturated fats tend to be found in animal foods such as beef, pork, eggs, and cheese, but palm oil and coconut oil are also saturated. Unsaturated fats are found in other plant oils such as corn oil, sunflower oil, and safflower oil, but certain fish oils are also unsaturated, and even pork contains unsaturated fatty acids.

ROLE OF FATS IN THE HUMAN BODY: The triglyceride forms of true fats are a storage form for excess food, that is, they are stored energy. Any type of food consumed in excess of the body’s caloric needs will be converted to fat and stored in adipose tissue. Most adipose tissue is subcutaneous, between the skin and muscles.

RELATED;

1. PROTEINS

2. CARBOHYDRATES

3.  BIOMOLECULES AND CHEMICALS OF LIFE

REFERENCES

FOLIC ACID

Therapeutic Class: Water-soluble vitamin

ACTIONS AND USES: Folic acid is administered to reverse symptoms of deficiency, which most commonly occurs in patients with inadequate intake, such as with chronic alcohol abuse. Because this vitamin is destroyed at high temperatures, people who overcook their food may experience folate deficiency. Pregnancy markedly increases the need for dietary folic acid; folic acid is given during pregnancy to promote normal fetal growth. Because insufficient vitamin B12 creates a lack of activated folic acid, deficiency symptoms resemble those of vitamin B12 deficiency. The megaloblastic anemia observed in folate-deficient patients, however, does not include the severe nervous system symptoms seen in patients with B12 deficiency. Administration of 1 mg/day of oral folic acid often reverses the deficiency symptoms within 5 to 7 days.

ADVERSE EFFECTS: Adverse effects during folic acid therapy are uncommon. Patients may feel flushed following intravenous (IV) injections. Allergic hypersensitivity to folic acid by the IV route is possible.

INTERACTIONS: Drug–Drug: Phenytoin, trimethoprim–sulfamethoxazole, and other medications may interfere with the absorption of folic acid. Chloramphenicol may antagonize effects of folate therapy. Oral contraceptives, alcohol, barbiturates, methotrexate, and primidone may cause folate deficiency.

RELATED;

1. VITAMIN A

2. VITAMIN C

3.  BIOCHEMISTRY

REFERENCES