Biological molecules 2018
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The document discusses the key components of DNA, carbohydrates, proteins, fats, vitamins C and D. It provides information on their chemical composition, roles in the body, food sources, and common tests used to identify each one.
Biological molecules 2018
- 2. DNA A DNA molecule looks like a twisted ladder, with two long strands parallel to one another with bases in between forming cross links; we call this shape a double helix. There are four types of bases, we give them letters A, T, C and G. Base A always pairs with T while base C always pairs with G. The sequence of these bases codes for the sequence of amino acids that make up proteins, different sequences code for different characteristics.
- 3. Carbohydrate molecules contain: C, H, O H:O is 2:1 like in water molecule Made up of smaller molecules : sugars or monosaccharides. e.g. glucose, fructose … we call them simple sugars Two sugars bonded together are called disaccharides e.g. maltose, lactose, sucrose. Many sugars bonded together make a polysaccharide e.g. starch, cellulose, glycogen. Carbohydrates are a source of energy to our bodies. Carbohydrates Plant cells for storage Plant cell walls For support Animal cells for storage
- 4. Starch granules in cells
- 5. Food rich in carbohydrates
- 6. We use Iodine solution (I2/KI), which is a yellowish brown solution that turns to a blue-black colour when it reacts with starch To test for starch
- 7. We use Benedict’s solution to test for reducing sugars. It is a Blue solution, when a reducing sugar is mixed with Benedict’s solution and boiled it forms a precipitate that is green, yellow, orange or brick red. To test for reducing sugars
- 8. Protein molecules contain elements: C,H,O,N (S,P) Proteins are made of smaller molecules called amino acids. Two amino acids bonded together are called dipeptides. Many amino acids bonded together make a polypeptide. Proteins are needed to make: 1. Enzymes 2. Haemoglobin 3. Muscles fibers 4. Hair and nails (Keratin) 5. Cell membranes of cells 6. As a source of energy during starvation. Proteins
- 9. Food rich in protein
- 10. We use NaOH and CuSO4 (Biuret solution) that has a pale blue colour, when it reacts with proteins it changes its colour to lilac, or purple or mauve. To test for proteins
- 11. Fat molecules contain elements: C,H,O Each fat molecule contains one glycerol and three fatty acids Fats are needed to: 1. Make cell membranes of cells 2. Good energy storage 3. Act as a heat insulator under the skin 4. Protect some organs Fats
- 12. Foods rich in fat
- 13. Add Ethanol to the sample then shake vigorously to dissolve the fat, then add water. A milky/cloudy appearance is formed. To test for fats
- 14. There are many vitamins known to us by now, we will study vitamin C and vitamin D as examples. Vitamin C, the first discovered vitamin, is needed by the body to make an important protein called collagen that toughens the skin, walls of blood vessels and bones. Lack of vitamin C causes inability to form collagen fibres which gives strength to blood vessels and skin. Deficiency symptoms: bleeding gums, skin ulcers. Deficiency disease: scurvy Vitamins
- 15. Citrus fruits Bell peppers Dark leafy vegetables Tomatoes, guava Broccoli, grapes Foods rich in vit. C
- 16. Use DCPIP a blue stain that becomes colourless when reduced. To compare the amount of ascorbic acid (vit. C) we can count the number of drops (or …) needed to change the blue DCPIP into colourless. To test for Vitamin C
- 17. Your body must have vitamin D to absorb calcium and promote bone growth. Too little vitamin D results in soft bones in children (rickets) and fragile bones in adults (osteoporosis). Vitamin D
- 18. Fish especially fish oil Milk and milk products Egg yolk Mushrooms Our skin can make vit. D when exposed to sunlight Vitamin D