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Biological Molecules - Coggle Diagram
Biological Molecules
Fats
(organic molecules made of the elements carbon, hydrogen and oxygen. Fats contain less oxygen in proportion to hydrogen. There is no fixed ratio/ formula)
A fat molecule is made of (1) glycerol and (3) fatty acid chains. It can be broken down by enzyme lipases
Found in, nuts, olives, butter, corn oil
Fats are needed for
- are a source and store energy
- act as an insulating material to prevent excessive heat loss
- are a solvent for fat soluble vitamins and some hormones
- form the main part of cell membranes
- help reduce water loss from skin surface
Low-Density Lipoprotein
("Bad" cholesterol)
- Delivers cholesterol to body cells
- Can build up plaque and
narrow arteries
- High levels risks of heart disease
Saturated fat
(Too much may increase cholesterol levels)
- Found in butter, cheese, full-cream milk, fatty meat,
chicken skin, coconut oil, palm oil
Testing for Fats
Liquid sample:
- Add 2 cm^3 of ethanol to 2 cm^3 of food sample
to a clean test-tube.
- Shake the contents of the tube vigorously.
- Add 2 cm^3 of water into the test-tube and
shake the mixture.
If Fats are present, a white emulsion is produced
Solid sample:
- Crush the solid sample into small pieces using a mortar and pestle and place the pieces in a test-tube
- Add 2cm^3 of ethanol into the test-tube and shake thoroughly.
- Allow the solid particles to settle. Carefully decant the ethanol (pour off the top layer of ethanol) into another test-tube containing 2cm^3 of water and shake the mixture.
-
High-Density Lipoprotein
("Good" cholesterol)
- Removes excess cholesterol from blood vessels
- Helps prevent plaque build-up
- Low level risks of heart disease
Unsaturated fat
(Generally better for heart health)
- Found in olive oil, canola oil, peanut oil, avocado, almonds,
peanuts, cashew nuts
-
Polyunsaturated fat
(Includes essential fats like omega-3 & omega-6)
- Found in Fish (salmon, sardine, mackerel), fish oil,
sunflower oil, corn oil, soybean oil, seeds
-
Carbohydrates
(organic molecules made up of the elements carbon, hydrogen and oxygen. The hydrogen and oxygen atoms are present in the ratio 2:1)
Sugars
(sweet and soluble in water. When dissolved in water, they will lower the Water potential of the solution. Sugars provide us with energy to do work and carry out activities)
-
Double sugars (2)
-
-
- Two single sugars joined together
- Cannot pass through cell membrane, hence, they are broken down into monosaccharides
-
Needed for
- as a substrate for respiration, to provide energy for cell activities
- to form supporting structures (eg. cell wall)
- to be converted into other organic compounds (eg. amino acids & fats)
- for the formation of nucleic acids (eg. DNA)
- to synthesise lubricants (eg. mucus -> carbohydrate + protein)
- to synthesise the nectar (a sweet liquid to attract insects) in some flowers.
Found in rice, bread, noodles, cereals
Proteins
(organic molecules made up of the elements carbon, hydrogen, oxygen and nitrogen)
A protein molecule is made up of smaller basic units called amino acids. (An amino group, an acid group and a side chain)
• Amino acids are the building
blocks of proteins.
• Peptide bonds link up amino acids
to form a polypeptide.
• Two or more polypeptide chains
fold to form a 3-D molecule,
called protein.
Found in red meats, beans, egg whites and milk/cheese, lentils
Proteins is needed for
- new protoplasm for growth and repair of worn-out cells
• enzymes and some hormones
• antibodies
Testing for proteins
Biuret test (method 1, recommended):
- Add 2 cm^3 of biuret solution to 2 cm^3 of food
sample to a clean test tube.
- Shake well and allow the mixture to stand for
five minutes.
If Proteins are present, solution turns from blue to violet
Biuret test (method 2):
- Add 2 cm3 of food sample to a clean test
tube
- Add 1 cm3 of sodium hydroxide solution
to the sample and shake well
- Add 1% copper(II) sulfate solution, drop
by drop, gently shaking after each drop
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Food is essential for all living organisms. They contain nutrients (water, carbohydrates, fats and proteins) that we need.
Water is essential because
- is a solvent in which chemical reactions take place
- is essential for photosynthesis
- keeps cells turgid or firm
- helps in the transport of mineral salts in plants
- regulates body temperature
- helps to transport dissolved substances around the body