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Define the structure of carbohydrates, fats and proteins.

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Define the structure of carbohydrates, fats and proteins. Carry out tests to identify starch, reducing sugars, fats and proteins. State the role of water in living ... – PowerPoint PPT presentation

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Title: Define the structure of carbohydrates, fats and proteins.


1
Learning Outcomes
  • Define the structure of carbohydrates, fats and
    proteins.
  • Carry out tests to identify starch, reducing
    sugars, fats and proteins.
  • State the role of water in living organisms

2
3.1 The Building Materials of Life
Water
  • 2 hydrogen atoms attached to the oxygen atoms
  • V-shaped molecule
  • Stronger pull of O atom result in H2O becoming
    slightly polar
  • O atom is more negative, H atoms are more positive

3
3.1 The Building Materials of Life
Water has a high heat capacity
  • Water has a high heat capacity due to the many
    bonds between water molecules.

4
3.1 The Building Materials of Life
Ice is Less Dense than Water
  • As water loses heat, the molecules slow down.
  • More bonds are formed between the molecules.
  • Ice is formed and it is less dense than water
    since its molecules are further apart than in
    liquid state.

5
3.1 The Building Materials of Life
Cohesive and Adhesive Forces
  • Cohesive force ease with which hydrogen bonds
    are formed between water molecules.
  • Adhesive force attraction between two different
    kinds of molecules.

6
3.1 The Building Materials of Life
Water as a Solvent
  • Also a very good solvent due to it being
    slightly polar.

7
3.1 The Building Materials of Life
Role of Water in Living Organisms
  • Absorbs and removes heat produced by metabolic
    activities.
  • Removes heat by evaporation of sweat.
  • Its unique density as ice results in ice floating
    over slightly warmer water.
  • Insulates water from further loss of heat.
  • Ensures survival of aquatic organisms.
  • Forms a large part of the cytoplasm of the cell,
    tissue fluid and transporting medium.
  • In plants, it helps the cells to maintain turgor
    pressure and keep their shape. Also essential in
    photosynthesis.

8
3.1 The Building Materials of Life
Carbohydrates
  • Contain carbon, hydrogen and oxygen.
  • Hydrogen Oxygen ? 2 1
  • Chemical formula Cm(H2O)n

9
3.1 The Building Materials of Life
Carbohydrates
  • Monosacharides (single sugars) are carbohydrates
    which cannot be broken down into simpler form.
  • E.g. glucose, fructose, galactose.
  • Sweet and soluble

10
3.1 The Building Materials of Life
Carbohydrates
  • Disaccharides (double sugars) are created when
    two mono-saccharides become linked.
  • Sweet and soluble

11
3.1 The Building Materials of Life
Carbohydrates
  • Sugars may be classified as reducing or
    non-reducing sugars
  • Eg. glucose, fructose, maltose, lactose are
    reducing sugars

12
Test for Reducing sugars
  • Add 2ml of Benedicts Solution to 2ml of test
    solution in a test-tube.
  • Shake well to mix.
  • Place test-tube in boiling water bath for
  • 5 min.
  • Solution turns green
  • Solution forms yellow ppt
  • Solution forms ornage-red ppt
  • Solution remains blue

13
3.1 The Building Materials of Life
Carbohydrates
  • Polysaccharides are long chains or polymers of
    monosaccharides.
  • The chains produced can be branched or
    unbranched. The chains may also be folded, thus
    making them compact and ideal for storage.
  • The large size of the molecules makes them
    insoluble so do not affect water potential and
    they cannot easily diffuse out of the cell.
  • Functions mainly for storage and provide
    structural support.

14
3.1 The Building Materials of Life
Carbohydrates
  • Storage polysaccharides
  • Starch is a polymer of glucose molecules.
  • Stored as starch granules in plastids in plant
    cells or tissue.

15
3.1 The Building Materials of Life
Carbohydrates
  • Storage polysaccharides
  • Glycogen is also a polymer of glucose.
  • Primary store of carbohydrates in animals.
  • Stored in liver and skeletal muscles of
    vertebrate animals.

16
3.1 The Building Materials of Life
Carbohydrates
  • Structural polysaccharides
  • Cellulose is the most abundant organic compound
    on the Earth.
  • Long cable-like bundles of fibrils in the cell
    walls of all plant cells.

17
3.1 The Building Materials of Life
Carbohydrates
  • Structural polysaccharides
  • Most animals do not have the enzymes to break the
    molecular linkages.
  • However, it aids peristalsis.
  • For herbivores, cellulose is digested by
    micro-organisms present in the gut of those
    animals.

18
Why Glycogen and Starch are suitable storage
materials?
  • Insoluble so
  • Large molecules so
  • Easily broken down (hydrolysed) so
  • Molecules have compact shapes, folded so

19
Test for starch
  • Add 2ml of Iodine solution to 2ml of test
    solution.
  • Shake well to mix.
  • Solution turns blue-black
  • If solid, its stained blue-black
  • Solution remains yellowish brown
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