1. proteins

2. proteins
Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

3. Amino acid
amino acid are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids.

4. Amino acid general formula for α-amino acid is
where R is an organic substituent. The amino group is attached to the carbon atom immediately adjacent to the carboxylate group (the α–carbon ).

6. Amino acid: There are two types of amino acids:
non-essential amino acids can be made by the body.
essential amino acids cannot be made by the body and must be taken from food. There are 8 essential amino acids.

7. Amino acid
essential amino acid isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
histidine is considered semi-essential because the body does not always require dietary sources of it.

8. Importance of proteins:
Structural Proteins (Membranes, cartilages, Connective tissues).
Transport Proteins
Direct biochemical reactions (enzymes)
Defend the body against infection (antibodies)
Control metabolic process (hormones)
Contractile Proteins - are responsible for movement

9. albumin
Albumin is the main protein of blood plasma; it binds to water, cations (such as Ca2+, Na+ and K+), fatty acids, hormones, bilirubin and drugs

10. gelatin
Gelatin is a translucent, colorless, brittle (when dry), tasteless solid substance
derived from the collagen inside animals' skin and bones.
It is commonly used as a gelling agent in food, pharmaceuticals, and cosmetic manufacturing.

11. Physical properties

12. a. Protein solubility
All proteins dissolve in dilute acid ,base and water

13. b. Coagulation and precipitation test
1.precipitation by heat: White turbidity will appear

14. b. Coagulation and precipitation test
2.precipitation by conc. Acid:
Add 2ml of conc. Nitric acid in a test tube then in the wall of the tube add 2ml of protein solution
Result
White ppt will appear

15. b .Coagulation and precipitation test
3.Precipitation by minerals
Result:
Ppt will appear

16. b. Coagulation and precipitation test
4.precipitation by alkaloids
Result:
Ppt will appear

17. b. Coagulation and precipitation test
5.preciptation by alcohol :
Add to 3ml protein solution 6ml of(70-90%) of ethyl alcohol
Result:
Ppt will appear

18. c. Gel formation test:
Dissolve 0.5 g of gelatin in 10ml hot H2O in test tube then cool the test tube in ice bath
Result:
Gel will formed

19. Chemical tests

20. Chemical tests: General test for all protein Biuret test:
Add 3ml of protein solution , 3ml of 10% NaOH with shake, then add 2 drops of 1% CuSO4 after shake violet color will appear

21. Chemical tests Differentiation (specific) test: Millon test:
Add 2ml of protein solution, 5drops of millon’s reagent.
Result:
+ve albumin (white ppt)
-ve gelatin (no white ppt)
Then heat the test tube . red ppt will appear with (albumin and gelatin)

22. Chemical tests: Differentiation (specific) test: Lead acetate test :
Add to 0.5 ml of protein solution 0.5ml of 20% NaOH heat the test tube in water bath for 1 min. then add 2 drops of conc.lead acetate
Result:
Brown color(+ve) with albumin
-ve with gelatin

23. Thank you and good luck in your future