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The macro-molecules of life

The macro-molecules of life. What are the main components of our diet?. The key components life are carbon-based macromolecules. Carbohydrates Lipids Proteins (Nucleic Acids – GENETICS). These large macromolecules may consist of thousands of covalently bonded atoms .

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The macro-molecules of life

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  1. The macro-molecules of life

  2. What are the main components of our diet?

  3. The key components life are carbon-based macromolecules • Carbohydrates • Lipids • Proteins • (Nucleic Acids – GENETICS) These large macromolecules may consist of thousands of covalently bonded atoms

  4. How big is a macromolecule?

  5. How big is a macromolecule?

  6. Where is carbon on the periodic table?

  7. Carbon has 4 valence electrons Therefore it can have bond with up to 4 other elements.

  8. Monomer units join together via CONDENSATION REACTIONS • Monomers are connected by reactions in which two molecules are covalently bonded together through the loss of a water molecule • This reaction is called a condensation (dehydration)reaction

  9. Breaking Down a Polymer: Hydrolysis Bonds between monomers are broken by the addition of water molecules

  10. Carbohydrates: Sugars, Starches, Fibre

  11. Where do carbohydrates come from? Mainly from PLANTS: animals store very little carbohydrate (as glycogen) in the body

  12. Why do we need carbohydrates?

  13. Why do we need carbohydrates? • Instant energy: 17 kJ/g of soluble sugar: glucose • Stored energy: Starch (plants)/ Glycogen(animals) • Structure: Cellulose (plant cell walls), Chitin (insect exoskeleton)

  14. What are carbohydrates made of? 3 kinds of atoms: carbon, hydrogen, oxygen [CA (H2OB)

  15. Different kinds of sugars

  16. Simple (reducing) sugars: Monosaccharides • All have the chemical composition (C6 H12 O6) • Glucose – respiratory substrate • Galactose (milk sugar) • Fructose (fruit sugar) • Small • Sweet • soluble

  17. Complex sugars: Disaccharides Small Soluble sweet

  18. Complex sugars: Disaccharides

  19. Polysaccharides: LARGE carbohydrates • Insoluble • Not sweet • Used for energy storage and plant, fungal cell wall structure

  20. Energy Storage Polysaccharides: Starch Energy storage in plants: easily converted into glucose, and vice versa

  21. Energy Storage Polysaccharides: Glycogen Found in animals, stored in liver and musclecells. Extensively branched • In humans, glycogen banks are SMALL, do not last longer than a day

  22. Structural Polysaccharides: Cellulose major component of plant cell walls Cellulose forms straight unbranched chains Because of the different structure, very few organisms have the enzymes necessary to break down cellulose Avery strong and resistant “insoluble fiber”

  23. Solubility of carbohydrates in water • Small carbohydrates (simple sugars and disaccharides) are soluble in water • Complex polysaccharides are often insoluble in water – cellulose, fibre

  24. Testing for sugars: Benedict’s solution All simple sugars (and some complex, including maltose) will reduce blue copper salts to a red colour

  25. Testing for starch: Iodine solution Brown iodine solution turns blue-black in the presence of starch

  26. Fats

  27. What are the sources of fat in our diet?

  28. Animal Fats Adipose tissue Milk fat Fish oils Plant oils Oils stored in plant seeds as a store of energy for germination

  29. Why do we need fats?

  30. Fats Serve Many Functions • Energy storage: store twice as many calories/gram as carbohydrates; 36 kJ/g • Protection of vital organs • Insulation • Cell membrane structure and function • Lipid hormones (based on cholesterol) are used as chemical messengers

  31. Fats (triacyglycerols or triglycerides) Large molecules created by condensation reactions between glycerol and 3 fatty mainly composed of carbon and hydrogen (with a small number of oxygen atoms)

  32. Saturated or Unsaturated Fatty Acids Stearic acid Solid at room temp SATURATED Oleic acid Liquid at room temp UNSATURATED

  33. Saturated and Unsaturated Fatty Acids Saturated fatty acids • have no double bonds between carbons • tend to be solid at room temperature • linked to cardiovascular disease • are commonly produced by animals • Examples: butter and lard Unsaturated fatty acids • have some carbon double bonds resulting in kinks • tend to be liquids at room temperature • are commonly produced by plants • examples are olive and corn oils 15

  34. What differentiates a saturated from an unsaturated fatty acid? • Saturated/unsaturated

  35. Are fats soluble in water? • Of course not!

  36. Key fats in life:Steroids • Steroid hormones are synthesised in the adrenal glands and the sex organs. • They include sex hormones: testosterone, oestrogen, progesterone and stress hormones (cortisol) • They are involved in metabolism, sexual function, inflammation and the immune response • They are able to diffuse easily through the phospholipid cell membrane into cells

  37. Key fats in life: phospholipids • Phospholipids have only 2 fatty acids. The third space is filled with a phosphate group. • Phospholipids are ampipathicbecause they have a negatively charged “head” which is hydrophilic and a non-polar “tail” which is hydrophobic

  38. Cholesterol • Cholesterol is a steroid which is a common component of animal cell membranes keeping them fluid • Many hormones including human sex hormones (oestrogen, progesterone, testosterone) are made of steroids: progesterone, testosterone, oestrogen etc

  39. Testing for fat: The emulsion test This test is used to test for the presence of lipids in a substance. • Lipids are soluble in ethanol but insoluble in water. • The substance is first dissolved in ethanol, then mixed with water • If lipid (fat) is present, then it will precipitate to the top of the solution as an emulsion

  40. Emulsion Test: Procedure • Add the food sample to ethanol, shake well. • Allow to settle in a test tube rack for 2 minutes for food to dissolve in ethanol. • Empty any clear liquid into a test tube containing distilled H2O. • A milky-white emulsion is a positive result: lipid is present. • If the mixture remains clear, there are no fats present in the sample • Lipids are insoluble in water and soluble in ethanol (an alcohol). • After lipids have been dissolved in ethanol and then added to H2O, they will form tiny dispersed droplets in the water. This is called an emulsion. • These droplets scatter light as it passes through the water so it appears white and cloudy.

  41. Proteins

  42. Where do proteins come from? PLANTS and ANIMALS

  43. Why do we need proteins?

  44. Why do we need proteins? • Growth and repair of new cells • Movement – skeletal and heart muscle • Repair • Communication- hormones • Enzyme function • Cell membrane function (channel and receptor proteins) • Immune response to infection (antibodies) • Energy: 17 kJ/g • 50% of the dry mass of any cell is protein • >10,000 different proteins • The most sophisticated, complex 3-dimensional structures

  45. What are proteins made of? severalkinds of atoms: carbon, hydrogen, oxygen, nitrogen, sulphur Proteins are polymers of amino acid monomers There are many different types of proteins Key types include STRUCTURAL proteins and FIBROUS proteins

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