1. Topic 2.2 Carbohydrates, proteins and lipids Mrs: Jackie Maldonado

2. Proteins Organic compounds containing  Oxygen  Carbon  Hydrogen  Nitrogen Polymer of amino acids

3. Proteins Each amino acid has a central carbon atom connected to

4. Proteins The amino group and carboxyl group gives amino acids their properties they are called functional groups A peptide bond forms when to amino acids bond together and water is removed. Condensation of amino acids results in a dipeptide if two amino connect together Condensation of more than two results in a polypeptide.

5. Condensation Notice there is an amino end and carboxyl end There are 20 different amino acids thus 20 R groups

6. Proteins Are water soluble Their solubility decreases with size. Some proteins are made of polypeptides and a non polypeptide part- conjugated proteins  Example hemoglobin Made of heme and globin Heme non protein part (contain iron) globin protein part Each hemoglobin has 4 polypeptides and 4 heme groups Prosthetic group- non protein part

7. Proteins Sequence of amino acids is controlled by the DNA GENE  protein  phenotype ALL OUR CHARACTERISTICS ARE DUE TO PROTEIN WE SYNTHESIZE WHICH IS DUE TO DNA INHERITED FROM OUR PARENTS

8. FunctionExamples TransportHaemoglobin- globular protein which transport oxygen Contraction of musclesActin and myosin involve in muscle contraction EnzymesTrypsin, amylase HormonesInsulin, growth hormone, prolactin Protection Against diseasesAntibodies Structural proteinsForm collagen and microtubules In bloodFibrinogen- clotting factor StorageProteins in legume seeds and beans

9. Structural organization of proteins Primary structure- linear sequence  Simplest structural level  Depends on the amino acid sequence  Amino acids are represented by three letters Examples VAL= valine COOH-TRP-SER-VAL-GLY-LEU-ARG-NH2 What does the – represent? How many amino acids composed this polypeptide?

10. Structural organization of proteins Secondary structure  Two different shapes: alpha helix or Beta pleated sheets  Alpha helix Results from the coiling of the polypeptide Hydrogen bonds maintain the coiling between amino and carboxyl group Campbell video.

11. Secondary structure continues B-pleated  Also maintain by hydrogen bonding.

12. Tertiary Structure Folding of the polypeptide due to different kinds of bonds  Hydrogen bonds  Disulphide linkage- cysteine contain sulphur and S-S form disulphide bonds  Electrovalent bonds between negative and positive groups.

13. Quaternary structure of proteins Only if it is made of more than one polypeptide Conjugated proteins binding with prosthetic groups Polypeptides are attached by hydrogen bonds, disulphide bonds and electrovalent bonds.

14. Examples based on structure Structural formExample SecondaryAlpha-Keratin- found in hair,wool, horns Beta- silk TertiaryLook over the internet QuaternaryHemoglobin

15. Fibrous and globular proteins Fibrous proteinsGlobular proteins Made of proteins in their secondary structure Tertiary or quaternary Made of repeated sequences of amino acids Folded resulting in a globular form Mostly insoluble in waterMostly soluble in water Examples: Keratin, silkEnzymes, hemoglobin, microtubules

16. Polar and non polar amino acids Being polar depends on the side chains of the amino acids (R group) Non polar amino acids- the ones with non polar R groups  Example Alanine and Valine

17. Polar and non polar amino acids Polar amino acids  R chain with polar groups; hydroxyl or Ketone  Examples Serine and Asparagine

18. Polar and non polar amino acids Polar amino acids are hydrophilic Non polar hydrophobic Solubility in water Hydrophilic proteins create hydrophilic channels through membranes