1. سمية شعراوي غرفة 2132 الساعات المكتبية semsharawi@kau.edu.sa

2. Marks 10 half-med exam 10 half-med exam 10 final exam 10 final exam 2 experiments + lab cleaning 2 experiments + lab cleaning 3 attending 3 attending

4. Molecular Biology is a field of science aims to understand the basis of living organisms’ chemical reactions necessary to build cell’s nutrients and to perform biological functions

5. organism Organization

6. Types of Molecules Inorganic molecules Organic molecules

7. Macromolecules Proteins Proteins Carbohydrates Carbohydrates Lipids Lipids Nucleic acids Nucleic acids

8. Proteins in cells & Tissues Proteins: One of the 4 macromolecules in living organisms, they are composed by binding of amino acids to each other with peptide bonds

9. Amino Acids: (NH 2 ) (COOH) (R) Building blocks of proteins. Amino acids consists of Amine group (NH 2 ) with basic properties, and Carboxyl group (COOH) with acidic properties, in addition to a side group (R) which determines the distinctive properties of amino acids. Carboxyl group Amine group Chemical formula of Amino acid

11. Amino acids are divided into many kinds dependents to R group: -P-Physical properties -C-Chemical properties -B-Biological properties

12. Neutral non polar amino acids: e.g. Tryptophan Neutral polar amino acids: e.g. Cysteine. Non-neutral amino acids: e.g. Arginine.

13. Levels of Structure in Proteins I- Primary Structure: I- Primary Structure: The binding of amino acids with peptide bond to form a linear chain of poly peptide. H2NH2N COO H ( Peptide bond ) Sequence of amino acids to form linear chain of polypeptide Ser Tyr His Met Glu PheArg Glu Ser His

14. Amino acids Peptide bond

15. II- Secondary Structure: II- Secondary Structure: The specific shape of protein results from Hydrogen (H)-bonding of the poly-peptide chain. Secondary structure is formed by formation of H bonds of Hydrogen atom of Amine group in one amino acid with Oxygen atom of carboxyl group of another amino acid. H- bond H2NH2N COOH Ser Tyr Met Glu Ala Val Cys Met Ser His Phe Ser Lys Glu Thr Arg

16. There are 2 forms of secondary structure: 1- α-helix 1- α-helix : e.g. Collagen protein in white fibers, and Elastine in elastic fibers. 2- β- plated sheet: 2- β- plated sheet: e.g. Keratin protein in hair and horny layer of skin.

17. Amino acids Alpha helix Hydrogen bond Secondary structure Pleated sheet

18. III- Tertiary Structure: There are 3 main types of chemical bonds : H-bond Ionic bond disulfide bond (-S-S-) - Format Globular protein e.g. enzymes.

20. IV- Quaternary Structure: The joining of multiple polypeptide molecules(units) into one large complex structure. Ex: Hemoglobin Quaternary structure: example is Hemoglobin, it consists of 4 polypeptid coiled chains to form one complex globular structure. (Iron) (Heme) (  chain) (  chain)

22. Proteins in cells Intestine Muscle

23. Protein hormone Insulin

24. Fibrous helical protein Elastine Collagen

25. Fibrous plated protein Keratin in Skin

26. Globular enzyme Phosphatase in lung Phosphatase in alimentary duct

27. Hemoglobin Hemoglobin in red blood cell

28. Detection of Amino Acids A) Detection of Tryptophan, phenylalanine: (1) in 2 test tubes Add 3 ml of each sample (egg white, milk) (2) Add 1 ml of conc. Nitric acid, then heat tube over flame for 1 min. (3) Cool tube (in ice), then add 4 ml of 40% NaOH.

30. Detection of amino acids Cyseine and Methionine 1- Put 5 ml of each sample (milk, egg white) in test tubes 2- Add 2 ml NaOH (40%), heat tubes on flame for 5 or more minutes 3- Cool tubes, then add 2 ml of lead acetate (5%).

32. Affecting Factors on Protein Denaturation: 1) In 5 test tubes, add 5 ml of egg white in each. Mark tubes from 1 to 5. 2) Put tube 1 in boiling water bath (or heat over flame) 3) In tube 2, add 3 ml of NaCl solution (ionic solution) 4) In tube 3, add 3 ml NaHCO (base) 5) In tube 4, add 5 ml HCl (acid) 6) In tube 5, add 5 ml ethanol alcohol (organic compound)

33. Thank you for listening