Option C - Human biochemistry

1. Option C - Human biochemistry C.1 Diet

2. C.1.1 Requirements of a Healthy Human Diet: • Water: necessary for life, biochemical activities within the body

3. Food groups: • 1) milk group-milk, cheese, yoghurt -->supplies calcium, protein, vit A&D • 2) meat group-meat, fish, poultry, eggs, legumes, nuts --> iron, vit B,energy • 3)vegetable and fruit group -->vit A&C • 4)bread and cereal group -->energy, vit, minerals, protein

4. Carbohydrates • source of calories (energy), glucose important in energy-producing cycles within cells. RDA

5. Proteins- • enzymes to catalyze the body's chemical reactions, hormones, muscle, connective tissue

6. Fats (& oils)- • concentrated source of energy RDA

7. Vitamins-

8. Minerals: • Calcium- blood, cells, body fluids, bones (its absorption is enhanced by vit D) Magnesium- maintains the electric potential across nerve-and-muscle-cell membranes • Phosphorus- bones & teeth • Iodine- essential for functioning of thyroid gland • Iron- hemoglobin, enzymes • Zinc- part of important enzymes in the body

9. Importance of a Balanced Diet: • -deficiency in caloric assumption results in deficiency diseases, starvation, or death • -overnutrition results in obesity, high blood pressure, diabetes, heart attacks • -excess in saturated fat consumption leads to rise in blood cholesterol levels- strokes • -deficiency in protein and minerals- anemia, edema, loss of pigment and hair, retarded growth

10. C.1.2 Calories and Enthalpy of Combustion: • -calories are the energy content of food • -energy is stored in chem bonds that link atoms and molecules. Energy is captured by the body during biochemical reactions involving the combustion of nutrients. This energy is used to drive life processes of cells. • Proteins and Carbohydrates- 4kcal/g • Fat- 9kcal/g • Alcohol- 7kcal/g

11. 20 different types R2 R1 R acid amino NH2 NH2 NH2 Ca Ca Ca COOH COOH COOH H H H R1 R2 NH2 Ca CO NH Ca COOH H H Polypeptide Protein Amino acid C.2 Proteins

12. C.2.1 2-Amino Acids: • -there are 20 different 2-amino acids • -they contain an amine group (NH2) on the central carbon atom (a), a carboxyl group and different R-groups. • -all amino acids are optically active (not needed, but good to know)

13. Amino Acid

14. C.2.2 POLYPEPTIDES: • -two amino acids join to form a dipeptide---the bond is called PEPTIDE BOND • -condensation reaction: a hydroxyl group is lost from one of the amino acids' carboxyl group, while the other amino acid loses a H from its amine group. (again, a diagram would be good, but...) • -amino acids join to form proteins

15. Let’s see how amino acids combine to make proteins. Amino acids combine in the presence of an enzyme during dehydration synthesis. Dehydration Synthesis O H H O H H C N C C C N H H O H R O H R H2O

16. Dehydration Synthesis H H H H O O • The compound produced from the dehydration synthesis of two amino acids is a dipeptide. • Water is also produced during the reaction. • The bond between the carbon atom and the nitrogen atom is a peptide bond. • A polypeptide is a long chain of amino acids containing many peptide bonds. • Proteins can contain two or more polypeptide chains. C C N C C N H O H R R H2O Peptide Bond

17. 20 different amino acids: many combinations C.2.4 PROTEIN STRUCTURE:-PRIMARY: • amino acids arranged in linear order

18. PROTEIN STRUCTURE: -SECONDARY: • -alpha helix:coil of polypeptides, with hydrogen bonds between the amide hydrogen atom in one peptide and the carbonyl oxygen atom of another peptide, at a distance of three amino acids. Coil chains are held together by DISULFIDE BONDS between adjacent chains. • -beta-pleated sheet: a folded sheet, stabilized by hydrogen bonds between the chains. There are NO disulfide bonds in this structure.

19. Alpha Helix

20. Oxygen Nitrogen R Group Hydrogen Carbon a Secondary Structure- b Sheet Carbonyl C H Bond

21. PROTEIN STRUCTURE: TERTIARY- • folded structure of chains of amino acids. 4 types of interactions • 1) Ionic bonds between R+ and R- • 2) H-bonds between partial - and partial + R-groups • 3) Disulfide bonds • 4) Hydrophobic interactions- non polar R-groups tend to stay close together because repelled polar substances surrounding proteins.

22. PROTEIN STRUCTURE:QUATERNARY • : more than one polypeptide chain join to form a protein--several folded chains joined by disulfide bonds (eg. hemoglobin)

23. Quaternary Structure The classic example- hemoglobin a2-b2 END OF PART 1 B/T- Figure 3.7

24. Disulfide Bonding V/V/P- Figure 16.6

25. Protein Separations Paper Chromatography Electrophoresis

26. An Experiment… • The solvent rises up the paper when the two touch. • The spot on the filter paper contains four different amino acids. • Watch what happens when the paper touches the solvent in the beaker…

27. Amino Acid Experiment • Which amino acid is the most soluble in this solvent (1-4)? • Number 1 is the most soluble. It remains dissolved in the solvent longer than the other amino acids and travels farther up the paper. • Which amino acid adheres most tightly to the paper (1-4)? • Number 4 sticks tightly to the paper and does not move as far as the other amino acids. 1 2 3 4

28. Gel Electrophoresis • Movement of charged molecules in an electric field. • Polyacrylamide gel provides a porous matrix • (PAGE – Polyacrylamide Gel Electrophoresis) • Sample is stained to make it visible in the gel. • Sample placed in wells on the gel. • Electric field across gel separates molecules. • Negatively charged molecules travel towards the positive terminal and vice-versa. • Cheap, fast and easy!

29. 1-D Gel electrophoresis • Separation in only 1 dimension: size. • Smaller molecules travel further through the gel – large ones get stuck earlier creating a separation.

30. 1-D cont. • DNA/RNA are stained with Ethidium Bromide which fluoresces under UV light. • Protein stained with Coomassie Blue which is blue in visible light. • Southern blots (DNA), Northern blots (RNA), Western blots (Protein). • Proteins are treated with the denaturing detergent SDS (sodium dodecyl sulfate) which coats the protein with negative charges, hence SDS-PAGE.

31.  C.2.5 FUNCTIONS:  • -structure, eg collagen (fibrous proteins) • -biological catalysts (eg. enzymes) • -transport eg. hemoglobin • -energy source

32. Functional Classes of Proteins • Receptors- sense stimuli, e.g. in neurons • Channels- control cell contents • Transport- e.g. hemoglobin in blood • Storage- e.g. ferritin in liver • Enzyme- catalyze biochemical reactions • Cell function- multi-protein machines • Structural- collagen in skin • Immune response- antibodies

33. Structural Classes of Proteins • 2. Fibrous Proteins (fibrils, structural proteins) • One dominating secondary structure • Typically narrow, rod-like shape • Poor water solubility • Function in structural roles (e.g. cytoskeleton, bone, skin)

34. Collagen: A Fibrous Protein Triple Helix Stabilizing Inter-strand H-bonds Gly-Pro-Pro Repeat V/V/P- Figures 6.17/18

35. Structural Classes of Proteins • 3. Membrane Proteins (receptors, channels) • Inserted into (through) membranes • Multi-domain- membrane spanning, cytoplasmic, and extra-cellular domains • Poor water solubility • Function in cell communication (e.g. cell signaling, transport)

36. C.3 Carbohydrates • Contain the elements Carbon Hydrogen & Oxygen • There are 3 types: • Monosaccharides • Disaccharides • Polysaccharides

37. C.3.1 MONOSACCHARIDES: • -all sugars that contain a single carbohydrate unit, with an empirical formula: CH2O • -contain a carbolyl group (C=O), and at least two hydroxyl groups (-OH) • -eg. -glucose, fructose, galactose

38. Monosacharides • If n=3, triose (glyceraldehyde) • If n=5, pentose (fructose, ribose) • If n=6, hexose (glucose, galactose) • Used for Energy and Building Blocks

39. C.3.2 GLUCOSE: • -C6H12O6 • -a main source of energy • -contains six carbons with an aldehyde group (H-C=O) on the first and hydroxyl groups on each of the remaining carbons • -in water, the 2nd C and the 6th C form a bond, forming a cyclic structure • -a-glucose: hydroxyl group on the sixth carbon is DOWN • -b-glucose: it is UP

40. Isomerism • They can exist as isomers:  &  glucose OH   OH

41. Disaccharides • Formed from two monosaccharides • Joined by a glycosidic bond • A condensation reaction: • glucose + glucose  maltose • glucose + galactose  lactose • glucose + fructose  sucrose

42. C C C C O O C C C C C C C C C 3.3 Condensation reaction OH OH

43. C C C C O O C C C C C C C C Condensation reaction OH OH

44. C C C C O O C C C C C C C C Condensation reaction O H2O

45. C C C C O O C C C C C C C C Condensation reaction 1 4 O A disaccharide 1,4 glycosidic bond

46. Polysaccharides • Polymers formed from many monosaccharides • Three important examples: • Starch • Glycogen • Cellulose

47. Amylopectin -glucose 1,4 and some 1,6 glycosidic bonds Branched structure Starch • Amylose -glucose 1,4 glycosidic bonds Spiral structure

48. Glycogen • Insoluble compact store of glucose in animals • -glucose units • 1,4 and 1,6 glycosidic bonds • Branched structure

49. O O O O O Cellulose • Structural polysaccharide in plants • -glucose • 1,4 glycosidic bonds • H-bonds link adjacent chains

50. C.3.4 FUNCTIONS OF POLYSACCHARIDES: • a number of monosaccharides joined together eg. Starch, a polymer of glucose, with formula (C6H10O5)n eg. Glycogen, same molecular formula--gives glucose when hydrolised, stored in liver and muscles as a reserve of carbohydrates. (this is not needed)