2. ο
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.
10
3. οο Carbohydrate molecules contain: C, H, O
ο H:O is 2:1 like in water molecule
ο Made up of smaller molecules : sugars or monosaccharides.
e.g. glucose, fructose β¦ we call them simple sugars
ο Two sugars bonded together are called disaccharides e.g. maltose,
lactose, sucrose.
ο Many sugars bonded together make a polysaccharide
e.g. starch, cellulose, glycogen.
ο Carbohydrates are a source of energy to our bodies.
Carbohydrates
Plant cells
for storage
Plant cell walls
For support
Animal cells
for storage
6. ο
ο 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. ο We use Benedictβs solution to test for reducing sugars.
ο It is a Blue solution, when a reducing sugar is mixed with
Benedictβs solution and boiled (in a water bath) it forms a
precipitate that is green, yellow, orange or brick red.
To test for reducing sugars
8. οο Protein molecules contain elements: C,H,O,N (S,P)
ο Proteins are made of smaller molecules called amino acids.
ο Two amino acids bonded together are called dipeptides.
ο Many amino acids bonded together make a polypeptide.
ο 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
10. ο
ο 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.
ο The more protein in the sample
the more intense the colour is.
To test for proteins
11. ο
ο Fat molecules contain elements: C,H,O
ο Each fat molecule contains one glycerol and three fatty
acids
ο 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
13. ο
ο 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. οο There are many vitamins known to us by now, we will
study vitamin C and vitamin D as examples.
ο 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.
ο Lack of vitamin C causes inability to form collagen
fibres which gives strength to blood vessels and skin.
ο Deficiency symptoms: bleeding gums, skin ulcers.
ο Deficiency disease: scurvy
Vitamins
15. ο
ο Citrus fruits
ο Bell peppers
ο Dark leafy vegetables
ο Tomatoes, guava
ο Broccoli, grapes
Foods rich in vit. C
16. ο
ο Use DCPIP a blue stain that becomes colourless
when reduced.
ο To compare the amount of ascorbic acid (vit. C) we
can count the number of drops (or β¦) needed to change
the blue DCPIP into colourless.
To test for Vitamin C
17. οο 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. ο
ο Fish especially fish oil
ο Milk and milk products
ο Egg yolk
ο Mushrooms
ο Our skin can make Vit. D
when exposed to
sunlight
Food rich in Vitamin D
20. ο
ο This mineral is a crucial component in the haemoglobin
molecule, that is found in β¦β¦β¦β¦
ο Haemoglobin is important to carry β¦β¦β¦β¦β¦β¦β¦β¦.
ο From the β¦β¦β¦β¦β¦β¦ to β¦β¦β¦β¦β¦β¦β¦β¦β¦β¦..
ο Deficiency symptoms : easily tired, pale face/skin.
ο Deficiency disease: Anaemia
Iron
21. ο
Foods rich in Iron
Spinach
Red meat
Beans
Liver
Dried fruit
Eggs