Flashcards BIOT CHEM LEC FINALS

Who discovered that certain substances in food could prevent deficiency diseases like beriberi?

Christiaan Eijkman

Who identified the importance of these substances and coined the term "vitamine" ("vital amine") in 1912?

Casimir Funk

Why was the name "vitamine" later shortened to "vitamin"?

Later, scientists discovered that not all vitamins are amines, so the name was shortened to "vitamin."

How are vitamins formed?

Vitamins are organic compounds produced through natural biochemical processes. Plants and microorganisms can produce many vitamins. Animals and humans obtain most vitamins through food. Some vitamins can also be produced by the human body.

Who first introduced the term "vitamin" in scientific literature

and when?, Funk in scientific literature, in 1911

What compound did Funk isolate

and from what?, A crystalline compound from rice polishings

What deficiency in pigeons was cured and prevented by this compound?

POLYNEURITIS

What was this compound found to be chemically?

An AMINE

Why was "vitamine" changed to "vitamin"?

Because it was found out that all these so-called essential compounds are not all amines.

Define VITAMIN.

Vitamins are ORGANIC COMPOUNDS that human tissues cannot synthesize but are required for normal growth and development and must be included in the diet.

What are the 3 characteristics of vitamins regarding quantity

deficiency, and onset of symptoms?, 1. Only small quantities are required, amounts that is insufficient in mass to be suppliers of carbon or nitrogen or to act as energy sources. 2. When intake in the diet is below the needed level, DEFICIENCY SYMPTOMS appear. 3. The time of onset of symptoms is a function of the size and the daily flux of the body reserves.

What are the two sources of vitamins for humans?

1. All vitamins can be supplied by FOODS, but no single food source is a rich source of all vitamins. 2. Some can also be synthesized by INTESTINAL MICROORGANISMS, but these microorganisms may not provide humans with the total requirements.

What are the two classifications of vitamins?

1. WATER-SOLUBLE VITAMINS - forms a chemically heterogeneous group which includes the beta vitamins, folic acid, niacin, pantothenic acid, biotin and vitamin C. 2. FAT-SOLUBLE VITAMINS - like vitamin A, vitamin D, vitamin E and vitamin K, and the so-called "ANTI-STIFFNESS" factor.

What can human tissues manufacture among the fat-soluble vitamins?

Human tissues can manufacture vitamin D but not the other fat-soluble vitamins, although they can make and handle ISOPRENE UNITS in the synthesis of cholesterol and UBIQUINONE (COENZYME Q).

What are cofactors?

Vitamins and their derivatives often serve as COFACTOR for enzymes. Vitamin cofactors are often referred to as COENZYMES.

What is an apoenzyme?

To be activated some enzymes depend on the conjugation of protein portion of the APOENZYME with a cofactor.

What is a holoenzyme?

HALOENZYME (Holoenzyme) are active enzymes that have the necessary cofactor bound to the apoenzyme.

Give an example of a cofactor-requiring enzyme.

Pyruvate carboxylase which needs biotin to become active.

What is a prosthetic group?

Co-factor that remain tightly bound to the enzyme and do not dissociate from it are called PROSTHETIC GROUP.

What minerals may also serve as cofactors?

MINERALS, particularly the TRANSITION METALS like zinc, iron, copper may also serve as cofactors.

What are the 3 roles of metal cofactors?

a. Play a direct role in the catalysis. b. Serves as a redox agent. c. Form complexes with substances.

What do metal cofactors give to enzymes?

Metal cofactors give the enzyme special catalytic powers or functional abilities that the enzyme protein does not have on its own.

What is a deficiency?

A deficiency occurs when the body does not get enough of a certain vitamin or mineral needed for normal body functions.

What are the non-specific symptoms of vitamin and mineral deficiencies?

ANEMIA, DERMATOLOGIC PROBLEMS, NEUROLOGICAL DISORDERS which are not distinguished from vitamin to vitamin or from many other types of metabolic disorders.

What are the causes of deficiencies?

1. INADEQUATE DIETARY INTAKE 2. INADEQUATE ABSORPTION which may result from biliary obstruction, since lack of bile leads to decreased absorption of the fat-soluble vitamins. 3. INADEQUATE USE which may result from transport protein.

Where is Vitamin A (Retinol) predominantly found?

In the livers of salt water fishes

Where is Vitamin A₂ abundant?

In the livers of freshwater fishes

What are the two vitamins important for?

The formation of the photo-active pigments in the retina of vision.

What is CAROTENE or PRO-VITAMIN A?

It is the inactive form of vitamin occurring abundantly in carrots and other yellow and green leafy vegetables.

What are the three forms of carotene?

Alpha, beta, and gamma carotene.

How many moles of active vitamin A do alpha and gamma carotene give?

Only one mole of active vitamin A

How many moles of vitamin A does beta carotene give and why?

Two moles of vitamin A because of two beta-ionone rings.

In what form is Vitamin A present in food?

Vitamin A is present as Vitamin A esters with fatty acids in the food.

What happens to Vitamin A esters in the small intestine?

The fatty acids are split-off and the free vitamin is then absorbed mainly through the lymphatic system and then appears in the blood plasma as the ester, indicating that RE-ETHERIFICATION is essential to its absorption.

How is Vitamin A resulting from the activation of carotenes absorbed?

Also absorbed in this manner (through the lymphatic system, re-esterified).

What happens to carotenes not converted to vitamin A?

Some of the carotenes which is not converted to vitamin A can be absorbed through the portal system, then into the blood.

What is needed for the absorption of carotenes but not for active vitamin A?

BILE ACIDS are needed for the absorption of carotenes, but not for the absorption of active vitamin A.

What are the 5 functions of Vitamin A?

1. GROWTH AND LONGEVITY - Vitamin A is needed for growth but the mechanism is unknown although it may be related to its requirement for tissue development. It is also believed to have some effect in prolonging the lifespan of an individual. 2. Needed for NORMAL DEVELOPMENT OF EPITHELIAL AND MUCOUS LININGS - Vitamin A is necessary for the normal integrity of the skin and mucous linings of various systems example respiratory tract, urinary tract. Such integrity increases the resistance to the entrance of invading microorganisms, which might otherwise cause some infective conditions. Hence, vitamin A has been called "ANTI-INFECTIVE" vitamin, by increasing the resistance of the skin and mucous linings against bacterial invasion. 3. IN THE EYES - Vitamin A is needed for the regeneration or formation of the photochemical substances, especially VISUAL PURPLE or RHODOPSIN. 4. REPRODUCTION - Vitamin A helps maintain the integrity of germinal epithelium in the males, so that deficiency will lead to relative sterility. In the female, the estrus cycle is not maintained, and with severe deficiency, stillbirths are common. 5. ON METABOLISM - It is needed in the conversion of trioses into glucose, which is then used to build up the glycogen reserves. It is also believed to be needed for the synthesis of adrenal glucocorticoids, thus its absence will lead to deficient gluconeogenesis.

What are the 7 deficiency manifestations of Vitamin A?

1. STUNTED GROWTH - It is one of the vitamins needed for growth in the individual. Vitamin A helps the body grow and develop normally. When there is not enough Vitamin A, children may grow slowly or have poor physical development. 2. IN THE EYES - XEROSIS CONJUNCTIVA/CONJUNCTIVAL XEROSIS, is the earliest sign seen, characterized by minute dry spots in the conjunctiva. XEROPHTHALMIA - "dry eyes" condition of the entire conjunctive, no secretion of tears due to the degenerative changes in the lacrimal glands. Later, infection may supervene, causing conjunctivitis, corneal ulceration, and may even involve the inner portions of the eyes, finally leading to blindness. 3. IN THE SKIN - the appearance of dry, scaly like (fish-like scales) with a small pustules resembling acne, around the hair follicles, especially on the extensor surfaces of the upper and lower extremities, shoulder, neck, back, lower abdomen and buttocks. This hardening of tissue is called KERATINIZATION. 4. IN THE BONES - cessation of bone growth, especially the epichondral bones of the skull, thus while the brain tissue grows normally skull growth is retarded resulting to the compression of the brain tissue, may lead to paralysis and nerve degeneration. 5. ON INFECTIONS - Vitamin A has been called the "ANTI-INFECTIVE" vitamin, although it does not actually destroy any microorganisms but it increases the integrity of the skin and mucous surfaces against the entrance of the microorganisms. 6. UROLITHIASIS - formation of the urinary stones due to keratinization of the mucous epithelium of the urinary tract. Vitamin A helps maintain the healthy lining of the urinary tract. When Vitamin A is lacking, changes in the urinary tract may make it easier for stones to form. 7. METABOLISM DISTURBANCES of Carbohydrates and nucleic acid metabolism.

What is the carbohydrate metabolism disturbance in Vitamin A deficiency?

Vitamin A helps the body properly use and control sugar (glucose). Deficiency can interfere with the body's normal use of carbohydrates and energy.

What is the nucleic acid metabolism disturbance in Vitamin A deficiency?

Vitamin A helps control cell growth and the production of DNA and RNA. When Vitamin A is deficient, normal cell growth and development can be affected.

Where is Vitamin A mainly stored?

Vitamin A is mainly stored in the liver.

What does the liver store regarding Vitamin A?

The body stores both carotene (which can be converted into Vitamin A) and active Vitamin A so that they can be used when needed. The liver acts like a storage area or reserve for Vitamin A.

What happens when we do not get enough Vitamin A from our food?

The body can use the Vitamin A stored in the liver to maintain normal functions such as vision, growth, healthy skin, and immunity.

When can the body's Vitamin A supply become depleted?

Especially when a person does not eat enough Vitamin A-rich foods for a long period of time. This can happen faster in children, pregnant women, or people with poor nutrition.

What happens once the liver's Vitamin A stores become too low?

The body can no longer get enough Vitamin A for its normal needs. This can lead to HYPOVITAMINOSIS A, OR VITAMIN A DEFICIENCY.

What is stored in the liver regarding Vitamin A?

Both CAROTENE AND THE ACTIVE VITAMIN are stored in the liver. However, a fast depletion is possible, so that even with the slightest deficiency in the diet will result in VITAMINOSIS A.

What are the daily requirements for Vitamin A?

Growing Children and Adults - 5,000 units daily. Pregnancy and Lactation - 6,000 - 8,000 units daily.

What is the ACUTE PHASE of Vitamin A toxicity?

Brought about by a single administration of 1,000 units or more. In a matter of hours, there will appear headache, nausea and vomiting and drowsiness due to increased intracranial pressure.

What is the CHRONIC PHASE of Vitamin A toxicity?

Results from a long-time ingestion of 100,000 units daily causing loss of appetite (anorexia), weight loss, dry itchy skin, bleeding lips, liver enlargement, bone and joint pains.

What is Hypervitaminosis A?

(Also known as Vitamin A toxicity) - the harmful effect of taking too much Vitamin A.

Quiz: It is the earliest sign seen

characterized by minute dry spots in the conjunctiva., a. Conjunctival xerosis

Quiz: What are the options for the earliest sign of Vitamin A deficiency?

a. Conjunctival xerosis b. Xerophthalmia c. Keratinization d. Urolithiasis

What is Vitamin D also known as?

It is also known as the ANTI-RACHITIC VITAMIN.

How many vitamins D are there

and how many are physiologically important?, There are at least 10 vitamins (from D₁ to D₁₀) but there are only two which are of physiological importance.

What are the two physiologically important Vitamin D?

1. VITAMIN D₂ or ERGOCALCIFEROL, derived from ERGOSTEROL through a series of photochemical reactions by the UV rays of the sun. 2. VITAMIN D₃ or CHOLECALCIFEROL, derived from the UV irradiation of 7-DEHYDROCHOLESTEROL.

What are excellent sources of the active Vitamin D?

Cod liver oil and other fish liver oils

Where are the pro-vitamins ergosterol and 7-dehydrocholesterol found?

They are found in the layers of the skin in man.

What converts the pro-vitamins to their active forms

and when is best to sunbathe?, Irradiation of UV rays of the sun (obtained by sunning oneself between 8:30 to 11:30 a.m.) convert to their corresponding active vitamin forms on the skin surfaces and then they are absorbed from the skin.

What is required for the absorption of the active Vitamin D from the intestine?

The presence of bile salts.

Where are the pro-vitamins converted into active forms?

The pro-vitamins are converted into active forms on the surface of the skin not inside the skin, so that if you wash away grease on the skin surface after sunbathing, the active vitamins will be washed away.

What is more physiological: go swimming then sunbathing

or sunbathing then swimming?, Thus it is more physiological to go swimming, then sunbathing. Rather than, go sunbathing then swimming.

What are the physiological actions of Vitamin D?

a. It is also the vitamin needed for normal growth related to CALCIUM AND PHOSPHORUS METABOLISM. b. It increases CALCIUM AND PHOSPHORUS ABSORPTION from the small intestines, and may be due to: (1) ability to change the pH of the small intestine (2) ability to increase the activity of the bile salts (3) increasing the permeability of the intestinal mucosa to calcium and phosphorus (4) it has a direct control in the biosynthesis of some protein component of the calcium-phosphorus transport system (5) increasing the citrate level thus c. increasing formation of CALCIUM-CITRATE COMPLEX, needed for greater absorption d. Directly involved in BONE FORMATION - the mechanism is obscure, but they may be due to its ability to increase the activity of the PHOSPHATASE ENZYMES, responsible for breaking inorganic phosphate compounds from organic compounds, thus making them available for bone formation. e. It has a specific function on RENAL TUBULAR RE-ABSORPTION OF PHOSPHORUS, thus help elevate plasma phosphatase f. It has a general stimulating effect on general body metabolism, thus, its deficiency will give a marked fall of BMR.

What is Rickets?

RICKETS - Rickets is a failure of newly formed bone (osteoid) and growth-plate cartilage to mineralize. It happens while the skeleton is still growing, so the growth plates (epiphyses) are affected.

When is Rickets most common?

Most common between 6 months and 3 years old, during the fastest bone growth.

What are the common causes of Rickets?

Too little sunlight, low dietary vitamin D, exclusive breastfeeding without vitamin D supplements (breast milk is low in vitamin D), dark skin pigmentation, fat malabsorption (celiac disease, cystic fibrosis), chronic kidney or liver disease, and rare inherited forms (vitamin D-dependent rickets, X-linked hypophosphatemic rickets).

What is Osteomalacia?

Osteomalacia is "soft bones" in adults. The growth plates have already closed, so the problem is defective mineralization of the bone matrix that is continually remodeled.

What are the symptoms of Osteomalacia?

Diffuse bone pain and tenderness, proximal muscle weakness, waddling gait, and pseudofractures (Looser's zones or Milkman's lines on X-ray).

Who are at-risk groups for Osteomalacia?

Elderly and homebound people, people who cover most of their skin or avoid the sun, pregnant women with closely spaced pregnancies, patients with malabsorption, and patients on long-term anticonvulsants (they speed up vitamin D breakdown).

Quick comparison: Rickets vs. Osteomalacia - Who?

Rickets: Growing children; Osteomalacia: Adults (after growth plates close)

Quick comparison: Rickets vs. Osteomalacia - Site affected?

Rickets: Growth plates and bone; Osteomalacia: Bone only

Quick comparison: Rickets vs. Osteomalacia - Main deformities?

Rickets: Bowlegs, knock-knees, rachitic rosary, craniotabes; Osteomalacia: Bone pain, pseudofractures, waddling gait

Quick comparison: Rickets vs. Osteomalacia - Key defect?

Rickets: Impaired mineralization of osteoid and cartilage; Osteomalacia: Impaired mineralization of osteoid

In children

the deficiency is called ___; in adults, it is called ___., In children, the deficiency is called RICKETS. In adults, the deficiency is called OSTEOMALACIA.

What are the deficiency manifestations of Vitamin D?

a. There is defective ossification - the bones become soft and pliable, with ensuing deformities, such as bowleggedness, knockedness, etc. b. Increased serum phosphate (hyperphosphatemia). c. Low calcium and phosphate blood level leading to osteoporosis. d. Delayed dentition. e. TETANY - a state of muscular twitching, on the slightest stimulation of any nerve trunk in the body. f. Tapping the ulnar nerve at the level of the inner elbow joint will result in the formation of the so-called "ACEOUCHEUR'S HAND" or OBSTETRICAL HAND.

What are the daily requirements of Vitamin D?

Depends upon the exposure to UV rays of the sun. Normally, the requirement is 400-800 units daily. Units: A measure of vitamin amount usually International Units (IU).

What is the toxicity of Vitamin D overdose?

Toxicity of overdose is quite rare. Only in recent times was high-dose vitamin D found to be curative for rheumatoid arthritis.

What is a real overdose of Vitamin D?

A real overdose has been encountered on an intake of 20,000-25,000 units daily. This is very much higher than the normal daily intake (400-800 units).

What are the symptoms of Vitamin D overdosage?

Nausea, anorexia, weakness, headache, digestive disturbances, polyuria, death may occur.

What is Vitamin E?

Vitamin E is a TOCOPHEROL derivative. It has several vitamins, but the most potent is tocopherol known as ANTI-STERILITY FACTOR.

What are the most common sources of Vitamin E?

It is widely distributed in plants and animals, but the most common sources are cottonseed oil, peanut germ oil and wheat germ oil.

How does Vitamin E differ from Vitamin A regarding storage?

It differs from Vitamin A in not being stored in the liver. However, the presence of Vitamin E increases Vitamin A storage in the liver.

How is Vitamin E absorbed?

It is absorbed in the small intestine which is not very efficient and requires the presence of bile salts or fats. There are water-soluble forms, which are more effective when given intramuscularly.

What are the physiological and deficiency manifestations of Vitamin E?

1. In rats (not established in humans) it is needed for normal integrity of the reproductive system especially in the formation of sperms, so that its deficiency in the rat will lead to STERILITY. This has been proven of some use in human. In the female rat - it will lead to HABITUAL ABORTION. Again, this has been useful in the human, as evidenced by the fact that several habitual abortion cases have been corrected by the administration of moderate doses of vitamin E. 2. It has SPARING ACTION on Vitamin A and carotene and has been pointed out to help in the storage of vitamin and carotene. The action of vitamin A becomes more effective in the presence of Vitamin E. 3. It serves as a CO-FACTOR or ELECTRON CARRIER in the ETS, probably functioning between cytochromes b and c. 4. It acts as an ANTI-OXIDANT by preserving the physiological lipid configuration of the cell membrane, whose action is more on linoleic acid and other unsaturated fatty acids. In this connection, it is added to cosmetics and beauty products, especially those with oil-basis, to prevent the rancidity of the preparations.

What is the daily requirement of Vitamin E?

The recommended daily requirement is 10 to 30 mgs.

Discovery of Vitamin E: 1922 - Who found it was essential for reproduction in rats and called it "Factor X"?

Herbert M. Evans and Katharine J. Scott Bishop

Discovery of Vitamin E: 1924 - Who named it "Vitamin E"?

Barnett Sure

Discovery of Vitamin E: 1936 - Who extracted alpha-tocopherol from wheat germ oil?

Evans' team

Discovery of Vitamin E: 1938 - Who completed chemical synthesis of Vitamin E?

Paul Karrer and colleagues

References for Vitamin E?

Brigelius-Flohé, R. (2021). Vitamin E research: Past, now and future. Free Radical Biology and Medicine, 177, 381-390. Evans, H. M., & Bishop, K. S. (1922). On the existence of a hitherto unrecognized dietary factor essential for reproduction. Science, 56(1458), 650-651. Evans, H. M., Emerson, O. H., & Emerson, G. A. (1936). The isolation from wheat germ oil of an alcohol, a tocopherol, having the properties of vitamin E. Journal of Biological Chemistry, 113(1), 319-332. National Institutes of Health, Office of Dietary Supplements. (2021). Vitamin E: Fact sheet for consumers.

Who discovered Vitamin K and when?

Danish researcher Henrik Dam in 1929.

How was Vitamin K discovered?

In his research with cholesterol in growing chicks, diets with fat removed resulted in extensive hemorrhages. Adding back cholesterol did not help, but there was another mysterious component which did, which was named Vitamin K—the Koagulation vitamin.

What is Vitamin K chemically?

It is a NAPHTHOQUINONE derivative.

What are the most potent members of Vitamin K?

(a) VITAMIN K₁ or PHYLLOQUINONE, obtained from alfalfa leaves (b) VITAMIN K₂ or FARNOQUINONE, produced through bacterial action, especially in the large intestines.

Types of Vitamin K: Vitamin K₁ (Phylloquinone) - where found?

Found mainly in green leafy plants, such as alfalfa. Obtained primarily from the diet.

Types of Vitamin K: Vitamin K₂ (Menaquinone) - where produced?

Produced by bacteria, particularly bacteria found in the large intestine. This is why intestinal bacteria can contribute to the body's vitamin K supply.

How is Vitamin K absorbed?

It is absorbed from the proximal portion of the small intestine, requiring the presence of bile salts. However, the water-soluble analog does not require bile salts when given orally.

Why does Vitamin K absorption require bile salts?

Because it is fat-soluble, its absorption requires bile salts. Bile salts help emulsify fats, allowing vitamin K to be absorbed more effectively.

What is the physiology of Vitamin K?

It is needed for the synthesis of PROTHROMBIN in the liver. In the form of CO-ENZYME Q, it is needed as a component of the ETS. It has a generic action of inducing RNA formation for the synthesis of blood-clotting proteins that is why it is called ANTI-HEMORRHAGIC FACTOR.

What is the role of Prothrombin?

Prothrombin is important for blood clotting. It helps in the formation of proteins involved in blood clotting. Because of its role in preventing excessive bleeding, it is called an anti-hemorrhagic factor.