3. 2- Proteins 3 1.A polypeptide is a polymer of amino acids connected in a specific sequence 2.A protein’s function depends on its specific conformation

4. 4 Their functions include structural support, storage, transport of other substances, intercellular signaling, movement, and defense against microbes. Some proteins works as enzymes in the cell that regulate metabolism by accelerating chemical reactions. All protein polymers are constructed from 20 monomers, called amino acids. Polymers of proteins are called polypeptides. A protein consists of one or more peptides (polypeptides) folded and coiled into a specific conformation 2- Proteins

5. 5 The physical and chemical characteristics of the R group determine the unique characteristics of a particular amino acid. Side chain Amino group Carboxyl group Protein is a polymer of amino acids (constructed from 20 amino acids) (to form Polypeptides). General Formula of the Amino Acid: C H R N H H C OHOH O The side chain R links withـ different compounds These components include a hydrogen atom, a carboxyl group, an amino group, and a variable R group (or side chain). Differences in R groups produce the 20 different amino acids.

6. 6 Peptide bond formed between the carboxyl group of one amino acid and the amino group of the other by dehydration. OHOHOHOH C C H R N H H O H CHR NHC OHOHOHOH O Peptide bond Polypeptide (Protein)Dehydration Amino acids Peptide Amino acids are joined together when a dehydration reaction removes a hydroxyl group from the carboxyl end of one amino acid and a hydrogen from the amino group of another. The resulting covalent bond is called a peptide bond. The Peptide Bond

7. 3- Lipids The Hydrophobic Molecules 7 1.Fats store large amounts of energy 2.Phospholipids are major components of cell membranes 3.Steroids include cholesterol and certain hormones 1.Fats store large amounts of energy 2.Phospholipids are major components of cell membranes 3.Steroids include cholesterol and certain hormones

8. Lipids are an exception among macromolecules because they do not have polymers. Lipids are an exception among macromolecules because they do not have polymers. The unifying feature of lipids is that they all have little or no affinity for water. The unifying feature of lipids is that they all have little or no affinity for water. – This is because their structures are dominated by non-polar covalent bonds. Lipids are the components of fats, and are highly diverse in form and function. Lipids are the components of fats, and are highly diverse in form and function. Although fats are not polymers, they are large molecules assembled from smaller molecules by dehydration reactions. Although fats are not polymers, they are large molecules assembled from smaller molecules by dehydration reactions. A fat is constructed from two kinds of smaller molecules, glycerol and fatty acids. A fat is constructed from two kinds of smaller molecules, glycerol and fatty acids. 8 1)- Fats:

9. 9 A fat is composed of three fatty acids linked with one glycerol molecule. A fat is composed of three fatty acids linked with one glycerol molecule. Fats are classified into Saturated and Un-saturated fats Fats are classified into Saturated and Un-saturated fats OHOH H H C C C C C C H H H H H H H H H O O C C C H H H H OHOH OHOH H H Dehydration Fatty Acid Glycerol Glycerol consists of a three C skeleton with an OH group attached to each C. Glycerol consists of a three C skeleton with an OH group attached to each C. A fatty acid consists of a carboxyl group (COOH) attached to a long carbon skeleton, often 16 to 18 carbons long. A fatty acid consists of a carboxyl group (COOH) attached to a long carbon skeleton, often 16 to 18 carbons long. Ester link

10. Fatty acids may vary in length (number of carbons) and in the number and locations of double bonds. carbon-carbon double bonds H If there are no carbon-carbon double bonds, then the molecule is a saturated fatty acid (has H at every possible position). 10 one or more carbon-carbon double bonds H If there are one or more carbon-carbon double bonds, then the molecule is an unsaturated fatty acid - formed by the removal of H atoms from the carbon skeleton.

11. 11 The Fatty acid components are saturated (there is no double bonds between the carbons. All C are linked with H. Thus, it is saturated with H. Most animal fats are saturated. They are solid at room temperature. Saturated fats-rich diet results in Atherosclerosis. These double bonds are formed by the removal of H atoms. Most vegetable fats (oils) and fish fats are unsaturated. They are liquid at room temperature. They can be synthetically converted to saturated (solid) by adding H (Hydrogenation). A)- Saturated Fats B)- Un-saturated Fats

12. 12 The phosphate group carries a negative charge. The fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head. Thus, it is amphipathic 2)- Phospholipids: Are major components of cell membranes Phospholipids have two fatty acids attached to glycerol and a phosphate group at the third position.

13. Steroids are lipids with a carbon skeleton consisting of four fused ملتحمة carbon rings. Different steroids are created by varying functional groups attached to the rings. 13 Cholesterol, an important steroid, is a component in animal cell membranes. Cholesterol is also the precursor المادة الخام from which all other steroids are synthesized. Many of these other steroids are hormones, including the vertebrate sex hormones. While cholesterol is clearly an essential molecule, high levels of cholesterol in the blood may contribute to Atherosclerosis. 3)- Steroids: Include cholesterol and certain hormones

14. The Summary 14 F a t s (Composed of Lipids) SaturatedSaturatedUnsaturatedUnsaturatedPhospholipidsPhospholipids Animal FatsVegetable Fats Bi-layer of cell membrane Hydrogenation SteroidsSteroids Sex Hormones & Cholesterol