Theme 8 VITAMINS

Theme 8

VITAMINS

Vitamin is an organic compound required by the organism as a nutrient in tiny amounts. In other words, an organic chemical compound (or related set of compounds) is called vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thirteen vitamins are universally recognized at present.

The discovery dates of the vitamins and their sources
Year of discovery	Vitamin	Food source
1913	Vitamin А (Retinol)	Cod liver oil
1910	Vitamin В1 (Thiamine)	Rice bran
1920	Vitamin С (Ascorbic acid)	Citrus, most fresh foods
1920	Vitamin D (Calciferol)	Cod liver oil
1920	Vitamin В2 (Riboflavin)	Meat, eggs
1922	Vitamin Е (Tocopherol)	Wheat germ oil, unrefined vegetable oils
1926	Vitamin В12 (Cobalamins)	liver, eggs, animal products
1929	Vitamin К1 (Phylloquinone)	Leafy green vegetables
1931	Vitamin В5 (Pantothenic)	Meat, whole grains, in many foods
1931	Vitamin В7 (Biotin)	Meat, dairy products, eggs
1934	Vitamin В6 (Pyridoxine)	Meat, dairy products
1936	Vitamin В3 (Niacin)	Meat, eggs, grains
1941	Vitamin В9 (Folic acid)	Leafy green vegetables

Vitamins are classified according to their biological and chemical activity, but not to their structure. Vitamins have diverse biochemical functions. Some have hormone-like functions as regulators of mineral metabolism (e.g., vitamin D), or regulators of cell and tissue growth and differentiation (e.g., some forms of vitamin A). Others function as antioxidants (e.g., vitamin E and sometimes vitamin C). The largest number of vitamins (e.g., B complex vitamins) function as precursors for enzyme cofactors, that help enzymes in their work as catalysts in metabolism. Vitamins may also be less tightly bound to enzyme catalysts as coenzymes, detachable molecules that function to carry chemical groups or electrons between molecules. For example, folic acid carries various forms of carbon group–methyl, formyl, and methylene – in the cell. Although these roles in assisting enzyme-substrate reactions are vitamins’ best-known function, the other vitamin functions are equally important.

The term vitamin was derived from “vitamine”, a combination word made up by Polish scientist Casimir Funk from vital and amine, meaning amine of life, because it was suggested in 1912 that the organic micronutrient food factors that prevent beriberi and perhaps other similar dietary-deficiency diseases might be chemical amines. This proved incorrect for the micronutrient class, and the word was shortened to vitamin.

Vitamins are classified as either water-soluble or fat-soluble. There are 13 vitamins in humans: 4 fat-soluble (A, D, E and K) and 9 water-soluble (8 B vitamins and vitamin C). Water-soluble vitamins are dissolved easily in water and, in general, are readily excreted from the body. Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats).

Vitamins are essential for the normal growth and development of a multicellular organism. Humans must consume vitamins periodically but with differing schedules, to avoid deficiency. Being overdosed, some vitamins cause side-effects such as nausea, diarrhea, and vomiting.

Task 1. Learn the following words by heart.

amount	[ə'maunt]	количество
catalyst	['kæt(ə)lɪst]	катализатор
cell	[sel]	клетка
compound	['kɔmpaund]	смесь, соединение, составной
consume	[kən'sju:m]	потреблять
deficiency	[dɪ'fɪʃ(ə)nsɪ]	недостаток, недостаточность, дефицит
development	[dɪ'veləpmənt]	развитие
diverse	[daɪ'vɜːs]	разнообразный
enzyme	['enzaɪm]	фермент
essential	[ɪ'senʃ(ə)l]	существенный, важный, необходимый, основной
growth	[grəuθ]	рост
intestinal tract	[ɪn'testɪn(ə)l] [trækt]	желудочно-кишечный тракт
multicellular	[mʌltɪˈsɛljʊlə]	многоклеточный
nutrient	['nju:trɪənt]	питательное вещество
obtain	[əb'teɪn]	получать
precursor	[prɪ'kɜːsə]	клетка- предшественник
prevent	[prɪ'vent]	предотвращать
quantity	['kwɔntətɪ]	количество
require	[rɪ'kwaɪə]	требовать(ч.-л)
scientist	['saɪəntɪst]	ученый
side-effect	[saɪd] [ɪ'fekt]	побочное действие
tissue	['tɪʃu:]	ткань

Task 2. Find in the text the following words and word combinations, reproduce the context they are used in and translate it into Russian.

1. organic compound

2. tiny amounts

3. sufficient quantities

4. biological and chemical activity

5. biochemical functions

6. hormone-like functions

7. detachable molecules

8. best-known function

9. derive

10. shorten

11. water-soluble

12. fat-soluble

13. normal growth

14. periodically

15. differing schedules

Task 3. Answer the questions.

1. What is vitamin?

2. Can vitamins be synthesized in sufficient quantities by an organism?

3. Where are vitamins obtained from?

4. How many vitamins are universally recognized at present?

5. How are vitamins classified?

6. What biochemical functions of vitamins do you know?

7. What does the term vitamin mean?

8. Who is the author of this term?

9. How many fat-soluble and water-soluble vitamins are there in humans?

10. What are vitamins essential for?

11. How must humans consume vitamins to avoid deficiency?

12. What happens when vitamins are overdosed?

Task 4. Match the English sentences with their Russian equivalents.

An organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet.	а) Витамины, возможно, менее тесно связаны с катализаторами ферментов
2. Some vitamins have hormone-like functions as regulators of mineral metabolism (e.g., vitamin D).	б) Витамином называют такое органическое химическое соединение, которое не может быть синтезировано организмом в достаточных количествах, и поэтому должно быть получено из пищевых продуктов.
3.Others function as antioxidants (e.g., vitamin E and sometimes vitamin C).	с) Другие функции витаминов также нужны.
4. The largest number of vitamins (e.g., B complex vitamins) function as precursors for enzyme cofactors.	d)Другие функционируют так антиоксиданты (витамин Е и иногда витамин С).
5. Vitamins may also be less tightly bound to enzyme catalysts.	е) Жирорастворимые витамины абсорбируются в желудочно-кишечном тракте с помощью липидов.
6. Folic acid carries various forms of carbon group – methyl, formyl, and methylene–in the cell.	f) Наибольшее число витаминов (например, витамины комплекса В) функционируют как клетки-предшественники для кофакторов ферментов.
7. The term vitamin was derived from vital and amine, meaning amine of life.	g) Некоторые витамины функционируют подобно гормонам, регулируя минеральный обмен (витамин D).
8. This proved incorrect for the micronutrient class, and the word was shortened to vitamin.	h)Термин витамин (vitamine) был образован от vital и amine, что означает амин жизни.
9. Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats).	i) Фолиевая кислота переносит в клетке различные формы углеводородов–метил, формил и метилен.
10. The other vitamin functions are equally important.	j) Это оказалось неверным в отношении класса микроскопических питательных элементов, и слово было сокращено до «витаминов».

Task 5. Translate the given sentences into Russian, your book and translate them back into English.

1. Vitamin is an organic compound required as a nutrient in tiny amounts by an organism.

2. Thirteen vitamins are universally recognized at present.

3. Vitamins are classified by their biological and chemical activity, not by their structure.

4. Vitamins have diverse biochemical functions.

5. The term vitamin was derived from “vitamine”, meaning amine of life.

6. Vitamins are classified as either water-soluble or fat-soluble.

7. Water-soluble vitamins are dissolved easily in water.

8. Vitamins are essential for the normal growth and development of a multicellular organism.

9. Humans must consume vitamins periodically but with differing schedules, to avoid deficiency.

10. Being overdosed, some vitamins may cause side-effects such as nausea, diarrhea, and vomiting.

Task 6. Retell the text.