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

2. Introduction (Polymers principles)
Cells join تربط smaller organic molecules together to form larger molecules.
These larger molecules called macromolecules, may be composed of thousands of atoms and weigh over 100,000 daltons.
The four major classes of macromolecules are: carbohydrates, lipids, proteins, and nucleic acids ( Will be studied later)
Three of the four classes of macromolecules form chainlike شكل السلسلة molecules called polymers.
Most macromolecules are polymers
Polymers consist of many similar or identical building blocks linked by covalent bonds.
The repeated units are small molecules called monomers.

3. Monomers are connected by covalent bonds by a condensation reaction or 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.
The covalent bonds connecting monomers in a polymer are disassembled تـُكسَــر by hydrolysis بإضافة 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.
Fig. 5.2a & b, Page 63

4. (Carbohydrates, Lipids, Proteins and nucleic acids)
Mono-mer
Di-mer
Poly-mer
أحادى
ثنائى
عديد
Polymer is a long molecule consists of a chain of similar building molecules (monomers) covalently bounded together.
Polymer can be built up يـُبـْنَى by linking its monomers by dehydration (removing H2O).
Polymer can be broken down يـُكَســًر إلى to its monomers by hydrolysis (adding H2O).
Page 62 – 63, Fig. 5.2

5. Fuel and Building Material (مادة الطاقة و البناء )
1- Carbohydrates
Fuel and Building Material (مادة الطاقة و البناء )
1. Sugars, the smallest carbohydrates, serve as fuel and carbon sources
2. Polysaccharides, the polymers of sugars, have storage and structural roles
Page 64-68

6. Carbohydrates include sugars.
Monosaccharides, are the simplest carbohydrates (simple sugars).
Disaccharides, double sugars, consist of two monosaccharides joined by a condensation reaction (dehydration).
Polysaccharides, are polymers of monosaccharides.
Monosaccharides have a carbonyl group and multiple hydroxyl groups.
If the carbonly group (C=O) is at the end of C chain, the sugar is called aldose (aldehyde sugar), if not, the sugars is called ketose (Ketone sugar).
Glucose called “aldose”, and fructose called “ketose”. They are structural isomers.
Monosaccharides may also exist as enantiomers.
For example, glucose and galactose, both six-carbon aldoses, differ in the arrangement around asymmetrical carbons ذرة الكربون الغير متماثلة.
Monosaccharides, particularly glucose, are a major fuel for cellular work.

7. C C 1- Monosaccharides Aldose Glucose Galactose C6H12O6 C6H12O6
Aldehyde sugars
1- Monosaccharides
Aldose O H C O H OH C
Glucose
C6H12O6
Galactose
C6H12O6 OH H OH H
Asymmetric C OH H OH H OH H H
Page 64, Fig. 5.3

8. C C C Fructose C6H12O6 OH H O O H OH O H OH Ketose Triose Sugar
Pentose Sugar
Hexose Sugar C OH H O C O H OH
Ribose
Ketone sugar C O H OH
Glyceraldehyde
Ketose
Page 64, Fig. 5.3

9. Aldehyde sugars Ketone
Monosaccharides are also classified by the number of carbons in the backbone.
Glucose and other six carbon sugars are hexoses سداسى.
Five carbon backbones are pentoses خماسى and three carbon sugars are trioses ثلاثى.
Aldehyde
sugars
Ketone
Fig. 5.3, Page 64

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

11. 2- Disaccharides 2(C6H12O6) C12H22O11 + H2O 1- Maltose
Consisted of 2 monosaccharide molecules during a dehydration reaction تفاعل نزع الماء.
1- Maltose
2(C6H12O6)
C12H22O11
+ H2O
2 Glucose
Maltose
FIG. 5.5a, Page 65

12. 2- Lactose (milk sugar): consists of Glucose + Galactose.
3- Sucrose (table sugar): consists of Glucose + Fructose.
Fig. 5.5, Page 65

13. 3- Polysaccharides
Consisted of few hundreds to few thousands of monosaccharides.
They have storage تخزينية and structural تركيبية roles.
Storage polysaccharides provide sugar for cell by hydrolysis.
Structural polysaccharides serve as building materials for the organism.

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

15. II- Glycogen ( in animal)
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

16. B)- Structural تركيبية Polysaccharides
I- Cellulose
It is the building material of plants (cell wall).
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 (e.g. in Termites and Cows stomach).
Fig. 5.7c, Page 67

17. Arrangement of cellulose in plants
Fig. 5.8, Page 68

18. The enzymes that digest starch cannot hydrolyze the beta linkages in cellulose.
Cellulose in our food passes through the digestive tract and is eliminated in feces as “insoluble fiber”.
As it travels through the digestive tract, it abrades the intestinal walls and stimulates the secretion of mucus.
Some microbes can digest cellulose to its glucose monomers through the use of cellulase enzymes.
Many eukaryotic herbivores آكلات العشب, like cows and termites, have symbiotic relationships with cellulolytic microbes, allowing them access to this rich source of energy.

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

20. Carbohydrates No. of C atoms No. of sugar molecules Monosaccharides
Triose (3C)
Glyceraldehyde
Pentose (5C)
Ribose
Hexose (6C)
Glucose
Monosaccharides
Disaccharides
Polysaccharides
Glucose & Fructose
Maltose & Sucrose
Location of Carbonyl Group
Storage
Structural
Starch (in plants) & Glycogen (in animals)
Cellulose (in plants)
& Chitin (in insects)
Aldose
C=O on top
Ketose
C=O in chain