Nutrients Flashcards
What are carbohydrates made of?
Contain the elements carbon, hydrogen and oxygen
What are the functions of carbohydrates?
- Source of energy
- Readily available and easy to digest
- Convenient source of energy - Support
- Cellulose in cell walls of plants - Starting point for the manufacture of other substances
- Excess carbohydrates can be converted into amino acids and fast
- Some are used to form nucleic acids - Production of nectar
- Produce nectar in flowers
Explain what are monosaccharides and name some examples?
Monosaccharides are single sugars.
Examples: Glucose, frutose and galactose
Explain what are disaccharides and name some examples.
Disaccharides are double sugars Exmples: 1. Sucrose (only one that is not a reducing sugar) - glucose + frutose → sucrose + water 2. Maltose - glucose + glucose → maltose + water 3. Lactose - glucose + galactose → lactose + water
Explain what are polysaccharides and give some examples.
Polysaccharides are complex carbohydrates.
- All are made up of glucose
Examples:
- Starch (plants)
- Cellulose (make up cell wall)
- Glycogen (animals)
Name and describe the test for reducing sugars.
Name: Benedicts test
Description (steps):
- Mash the solid then decant
- Add 2cm3 of benedict’s solution and an equal volume of food
- Place in boiling water bath and observe colour change
Results:
- Tiny amount - from blue to green
- Moderate amount - from blue to yellow or orange
- Large amount - from blue to brick-red
Name and describe the test for starch.
Name: Iodine-starch test
Description (steps)
1. Add a few drops of iodine solution to the food sample
Results
- If starch is present the food sample turns from yellow to blue-black
- If starch is not present the food sample will remain yellow
What are fats made up of?
Made up of carbon, hydrogen and oxygen
What are saturated fats?
- found in animal meats and oil from plants like palm
- fatty acid chains are closely packed due to the absence of double bonds
What are unsaturated fats?
- fatty acid chains produce kinks and are not closely packed due to the presence of double bonds
What are the functions of fats?
- Source of energy
- Fats are efficient storage of energy - Insulation
- Fats are natural insulating materials to prevent excessive heat loss - Solvent
- Certain vitamins and hormones are fats soluble and can only be absorbed into the body when dissolved in fats - Makes protoplasm
- Fats are found in cell membranes and they form part of the protoplasm of organisms - Protective layer
- Protective layer by protecting the internal organs from physical shock
Name and describe the test for fats.
Name: Ethanol emulsion test
Description (Steps):
- Add 2cm3 of food sample and equal volume of ethanol
- Add 2cm3 of distilled water
Results
- If fats/oil is present a cloudy white emulsion is observed
- If fats/oil is not present the solution remains clear
What are proteins made up of and what is its relationship to amino acids?
- Made up of carbon, hydrogen, oxygen and nitrogen
- Very little sulfur and phosphorus is present (some proteins do not contain these)
Amino acids
- Building blocks of proteins
- Amino acids → polypeptides → proteins
What are the functions of proteins?
- Growth and repair of cells
- Essential for the synthesis of protoplasm
- Growth and repair of worn tissues - Source of energy
- Provide energy when broken down - Structural protein
- Give structure to various parts of our bodies like keratin in hair, fibrin which aids in blood clotting - Form enzymes and antibodies
Name and describe the test for proteins.
Name: Biuret test
Description (Steps):
- 2cm3 of food sample and an equal volume of biuret solution
- Shake
Results
- If proteins are present the solution turns from blue to purple
- If proteins are not present the solution remains blue
