Food

Food and nutrients revision cards for Leaving cert.

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  • Created by: Schonie
  • Created on: 22-01-11 09:30

Food

Nutrition is the way in which an organism obtains and uses food.

Nutrients are needed for:

  • energy
  • to make chemicals needed for cell or metabolic reactions (eg.enzymes, antibodies)
  • as raw materials for growth and repair of structures in the organism
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Elements present in food

Common elements (CHONPS):

  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
  • Nitrogen (N)
  • Phosphorus (P)
  • Sulfur (S)

Trace elements (ZIC):

  • zinc (Zn)
  • iron (Fe)
  • copper (Cu)
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Elements present in food

Elements present as dissolved salts:

  • Sodium (Na)
  • Magnesium (Mg)
  • Chlorine (Cl)
  • Potassium (K)
  • Calcium (Ca)
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Biomolecules

Biomolecules are chemicals that are made inside a living thing.

Four major types of biomolecules found in food:

  • carbohydrates
  • lipids (fats, oils)
  • proteins
  • vitamins
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Carbohydrates

Elements: C, H, O

Ratio: Cx(H2O)y

Glucose: C6H12O6

Sources: breads, potatoes, rice, sugars, fruits, sweets, cakes

3 categories of carbohydrates:

1. Monosaccharides

2. Disaccharides

3. Polysaccharides

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Carbohydrates - Monosaccharides

-smallest units of carbohydrates

-sweet to taste, soluble in water

-contain single sugar unit

Glucose (C6H12O6)

- made in photosynthesis

- found in fruit, sweets, chocolate

- used for energy

Fructose

- same formula as glucose but atoms are arranged differently

- found in fruits, sweeter than glucose

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Carbohydrates - Disaccharides

- sweet to taste, soluble in water

- two monosaccharides joined together

  • sucrose (table sugar) = glucose + fructose
  • maltose (germinating seeds) = glucose + glucose
  • lactose (milk) = glucose + galactose
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Carbohydrates - Polysaccharides

 

- insoluble or slightly soluble in water

- many monosaccharides joined together

 

Starch (amylose):

- stored by plants

- long chains of glucose molecules

- easily digested

- rice, potatoes, flour, bread, pasta

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Carbohydrates - Polysaccharides 2

Cellulose

- structural carbohydrate in plants ( cell wall)

- long chains of glucose bonded together

- more difficult to break down

- very strong

- found in cotton and paper

- used as fibre (or roughage) in diet - stimulates peristalsis

Glycogen

- stored by animals

- made of many glucose molecules

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Lipids (fats and oils)

- Elements: carbon, hydrogen oxygen

- unline carbohydrates don't have any simple ration and little oxygen

- smallest lipids are made of one molecule of glycerol linked to three fatty acid molecules (triglyceride)

- found in butter, oils, cream, olives, fat on meat

Phospholipids are fat-like substances where one of the fatty acids is replaced by a phosphate group or has a phosphate group added to it.

(http://posterous.com/getfile/files.posterous.com/room212bio/pijPBMfQpByPmEEBvkLwPjo1GdBUAgz8U4bJsUwhEFO9p6dHF83kLh4FDiEU/Triglyceride3.jpg)

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Proteins

not finished

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Comments

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