1 CHAPTER 5 THE STRUCTURE AND FUNCTION OF MACROMOLECULES Page 62 Polymer principles And Macromolecules Polymer principles And Macromolecules

2 Monomers macromolecules) (Polymers)Cells join تربط smaller organic molecules (Monomers) together to form larger molecules (macromolecules) (Polymers), which may be composed of thousands of atoms. The four major classes of macromolecules are: 1)-Carbohydrates, 2)-Lipids, 3)-Proteins, 4)-Nucleic acids ( will be studied later ) Polymers principles

3 Monomers are connected by covalent bonds by a dehydration reaction تفاعل نزع الماء.Monomers are connected by covalent bonds by a dehydration reaction تفاعل نزع الماء. –One monomer provides a hydroxyl group and the other provides a hydrogen to form water. –This process requires energy and is aided by enzymes. Fig. 5.2a & b, Page 63 The covalent bonds connecting monomers in a polymer are disassembled تـُكسَــر by hydrolysis (hydration) reaction تفاعل إضافة الماء.The covalent bonds connecting monomers in a polymer are disassembled تـُكسَــر by hydrolysis (hydration) reaction تفاعل إضافة الماء. –In hydrolysis as the covalent bond is broken a hydrogen atom and hydroxyl group from a split water molecule attaches where the covalent bond used to be. –Hydrolysis reactions dominate the digestive process, guided by specific enzymes.

4 (Carbohydrates, Lipids, Proteins and nucleic acids) Mono-merDi-merPoly-mer Polymer is a long molecule consists of a chain of similar building molecules (monomers) covalently bounded together. Page 62 – 63, Fig. 5.2 أحادىثنائىعديد

5 Monosaccharides,Monosaccharides, are the simplest carbohydrates (simple sugars). DisaccharidesDisaccharides, double sugars, consist of two monosaccharides joined by dehydration. Polysaccharides,Polysaccharides, are polymers of many monosaccharides. 1- Carbohydrates Fuel and Building Material (مادة الطاقة و البناء )

6AldoseAldose Asymmetric C 1- Monosaccharides C C C C C C OH OHH OHH OHH OHH OHH H C C C C C COHOH OH OH OHH H H H OHH H Glucose C 6 H 12 O 6 Galactose Aldehyde sugars Page 64, Fig. 5.3

7Ketose C C C C C C OHH OH OH OH OHH H H H O HHFructose C 6 H 12 O 6 C C COHOHH OHH H Glyceraldehyde C C C C COHOH OH OHH H H OHH HRibose Ketone sugar Triose Sugar Pentose Sugar Hexose Sugar Page 64, Fig. 5.3

8 Monosaccharides are classified as following :- C Aldoses: are the monosaccharides of carbonyle group ( C=O) at the end of C chain (e.g. Glucose). C Ketoses: are the monosaccharides of C=O carbonyle group within داخل the C chain (e.g. Fructose). 3C Triose (3C): e.g. Glyceraldehyde. A- Based on the location of C=O B- Based on the number of C in the skeleton 5C Pentose (5C): e.g. Ribose. Hexose6C Hexose (6C): e.g. Glucose, Fructose and Galactose.

9 2- Disaccharides السكر الثنائى Consisted of 2 monosaccharide molecules during a dehydration reaction تفاعل نزع الماء. FIG. 5.5a, Page 65 Sucrose (table sugar): consists of Glucose + Fructose. Fig. 5.5, Page 65

10 3- Polysaccharides السكر العديد Consisted of few hundreds to few thousands of monosaccharides. They are two types: 1- Storage تخزينية. Provide sugar for cell by hydrolysis إضافة ماء. 1- Storage تخزينية. Provide sugar for cell by hydrolysis إضافة ماء. 2- Structural. Serve as building materials for the organism. 2- Structural تركيبية. Serve as building materials for the organism.

11 I- Starch ( in plants ) النشا A storage polysaccharide of plants (). A storage polysaccharide of plants (within plastids). It is consisted of thousands of  glucose molecules. Thus, it gives glucose when hydrolysed by special enzymes in human. Thus, it gives glucose when hydrolysed بإضافة الماء by special enzymes in human. Potatoes and grains are the major source of starch. A)- Storage نخزينية Polysaccharides Fig. 5.7, Page 67

12 II- Glycogen الجليكوﭽـين II- Glycogen ( in animals ) الجليكوﭽـين Stored in animal cells (). Stored in animal cells (e.g. liver and muscle cells in Human). It is consisted of thousands of glucose molecules. Thus, it gives glucose when hydrolysed. Fig. 5.7, Page 66

13 B)- Structural تركيبية Polysaccharides I- Cellulose Forms the micro-fibrils and cell wall in plants. It is consisted of thousands of β glucose molecules. Human cannot digest it, but some bacteria and protozoa can ( ). Human cannot digest it, but some bacteria and protozoa can (e.g. in Termites and Cows stomach). It is the building material of plants (cell wall). Fig. 5.7c, Page 67

14 II- Chitin الكيتين N It is consisted of thousands of glucose molecules with a N atom in one end. It is used to manufacture the surgical threads. It is the building material of the cuticle الجُـلَيد in insects. Fig. 5.9, Page 68

15 Carbohydrates Location of Carbonyl Group Aldose C=O on topKetose C=O in chain MonosaccharidesDisaccharides Polysaccharides Glucose & Fructose Maltose & Sucrose StorageStructural Starch (inplants) & Glycogen (inanimals) Starch (in plants) & Glycogen (in animals) Cellulose (in plants) & Chitin (in insects) & Chitin (in insects) No. of C atoms No. of sugar molecules Triose (3C) Glyceraldehyde Pentose (5C) Ribose Hexose (6C) Glucose

16 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: CHR N H H C OHOHOHOH O R - The side chain R links with ترتبط بـ different compounds - These components include a hydrogen atom, a carboxyl group, an amino group, and a variable متغيرة R group (or side chain). - Differences in R groups produce the 20 different amino acids. 2-Proteins

17 1.Hydrophobic: the amino acids that have hydrophobic R groups (non-polar). Fig. 5.15, Page 72 Amino acids الأحماض الأمينية 2- Hydrophilic: the amino acids that have polar R groups, making them hydrophilic. 3- Ionized: the amino acids with functional groups that are charged (ionized) at cellular pH (7). So, some R groups are bases, others are acids. 3- Ionized: the amino acids with functional groups that are charged (ionized) at cellular pH (7). So, some R groups are bases, others are acids.

18 The Peptide Bond الرابطة البيبتيدية 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 Page 73, Fig Polypeptide (Protein) Dehydration نزع الماء Amino acids Peptide

19 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.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. Fig. 5.16, Page 73 The repeated sequence (N-C-C) is the polypeptide backbone.The repeated sequence (N-C-C) is the polypeptide backbone. Attached to the backbone are the various R groups.Attached to the backbone are the various R groups. Polypeptides range in size from a few monomers to thousands.Polypeptides range in size from a few monomers to thousands.

20 Amino acids PeptidesPeptides Peptide ponds Dehydration Hydrophobic () Hydrophobic (non-polar R group) Hydrophilic () Hydrophilic (polar R group) Ionized (charged functional groups Ionized (charged functional groups) ProteinsProteins Polypeptides

21 3-Lipids; 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 Pages 69-71

22 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 Fig. 5.10, Page 69 Ester link In a fat, three fatty acids are joined to glycerol by an ester linkage, رابطة إستيرية creating a triacylglycerol.

23 A)- Saturated Fats الدهون المشبعة 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 التصلب الشريانى. 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 الهَدْرَﭽـَة). B)- Un-saturated Fats الغيرمشبعةالدهون B)- Un-saturated Fats الغير مشبعة الدهون

24 Phospholipids have two fatty acids attached to glycerol and a phosphate group at the third position.Phospholipids have two fatty acids attached to glycerol and a phosphate group at the third position. –The phosphate group carries a negative charge –The phosphate group carries a negative charge. Phospholipids; Are major components of cell membranes The fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head.The fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head. Thus, it is amphipathicThus, it is amphipathic Fig. 5.12, Page 70

25 At the surface of a cell, phospholipids are arranged as a bilayer طبقة مزدوجة.At the surface of a cell, phospholipids are arranged as a bilayer طبقة مزدوجة. –Again, the hydrophilic heads are on the outside in contact with the aqueous solution المحلول المائى and the hydrophobic tails from the core المركز. –The phospholipid bilayer طبقة مزدوجة forms a barrier حاجز between the cell and the external environment البيئة الخارجية. They are the major component of cell membranes.They are the major component of cell membranes.

26 F a t s (Composed of Lipids) SaturatedSaturatedUnsaturatedUnsaturatedPhospholipidsPhospholipids Animal FatsVegetable Fats Bi-layer of cell membrane Hydrogenationهَـدْرَﭽـَــــــــة SteroidsSteroids Sex Hormones & Cholesterol