Chemistry

Grade 12: ES and LH

 Contents:
Unit 1: food chemistry

Chapter 1: carbohydrates

Chapter 2: lipids

Chapter 3: proteins

Chapter 4: vitamins and minerals

Chapter 5: nutrition requirements

Chapter 6: the principle food

Chapter 7: food diet

Unit 2: current medical drugs

Chapter 10: current medical drugs.

 Unit 1: food chemistry
Chapter 1: carbohydrates

I-Food and their components:

1. Definition of foods:
Foods are complex substance obtained from animals and plants.
Food components are called nutrients include: carbohydrates, lipids, proteins,
vitamins and minerals.
2. Role of foods in the human body:
 They maintain life and growth
 They supply energy
 They build and replace tissues
3. Definition of complete food:
A complete food is a food constituted of all different types of nutrients.
Only maternal milk is considered as complete food.
II-Nutritional balance and nutritional requirements of human body:
1. Nutritional balance:
The nutritional balance is a function of individual needs, activities, physiological
state and environment.
2. Nutritional requirements:
 The structural requirements can be gotten from water some minerals
(calcium) and proteins are used to renew cellular constituents and to build
body tissues for young people.
 The energetic requirements can be gotten from carbohydrates lipids and
partially from proteins they are necessary for energy.
 The vitamins and some minerals are needed for protection and control
body function.

III-Carbohydrates and their role:

1. Definition of carbohydrates:
Its composed of three chemical elements: carbon (C ), hydrogen (H) and
oxygen(O) with the general formula Cn(H2O)m . They contain a carbonyl group
( C=O ) and hydroxyl groups ( -OH) .
 2. Role of carbohydrates in the human body:
 Carbohydrates linked to proteins and lipids play an important role in
the functioning of the organism.
 Carbohydrates storage in the form of glycogen provides a short term
energy reserve.
 Carbohydrates oxidation provides energy for the body.
3. Classification of carbohydrates:
Carbohydrates are classified according to their molecular size into
monosaccharides, oligosaccharide, and polysaccharides.

A-Monosaccharides:
Definition of monosaccharides: are the simplest units of carbohydrates that
cannot be broken down by hydrolysis.
Properties of monosaccharides:
 White crystalline solids
 Soluble in water
 Insoluble in non-polar solvent
 Sweet taste
 Non-branched in which all carbon atoms are linked by simple bond ( C-
C)
 Reducing agent due to the presence of free carbonyl group
 A reducing sugar can be detected (identified) by the Fehling’s test:
Reducing sugar + Cu2+ → Cu2O (red precipitate)
The three monosaccharides are:
Glucose:
 Found in fruit juice and honey
 It is an aldohexose (sugar having six carbon atoms and an aldehyde function)
Fructose:
 Found in fruit juice
 It’s a ketohexose (sugar having six carbon atoms and ketone function)
Galactose:
 Found in algae and linseed
 It’s an aldohexose (sugar having six carbon and an aldehyde function glucose
and galactose same general formula but differ in the position of hydroxyl
group ( -HO ) at the carbon 4)
B-oligosaccharide:

Definition of oligosaccharides: Number of monosaccharides unites range from 2

to 9
Two monosaccharides unites are linked together by glycosidic linkage (C-O-C)

Condensation
Monosaccharides + Monosaccharides disaccharides + water
Hydrolysis

The three oligosaccharides are:

1-Sucrose:
 Common table sugar
 Produced from beets and sugar cane
 Results from the condensation of glucose and fructose
 Glucose + fructose sucrose + water

2-lactoses:
 Found in milk
 Results from condensation of glucose and galactose
 Glucose + galactose lactose + water

3-maltose:
 Produced whenever starch is hydrolysis
 Glucose + glucose maltose + water

C- polysaccharides:
Number of monosaccharides unites is greater than 10
The three polysaccharides are:
1-starch:
 Contains only glucose
 Essential storage of polysaccharide in plants
 Found in plant tissues(potatoes, ceral grains)
2-glycogen:
 Essential storage polysaccharide in animals (site of storage: liver and
muscles)
 Is a highly branched polymer of glucose
 Soluble in water
 How to identify glycogen?
Gives brown color with iodine
3-celluolose:
 It is insoluble in water
 Is the structural components of the cell walls of plants
 Has linear unbranched chain
 Is highly resistance to hydrolysis
 Cannot be hydrolyzed in human’s digested tract because human lack the
specific enzyme (cellobiase) so it’s not a source of nutrition for human
 Chapter 2: Lipids

I. I-Definition of lipids:
Lipids are organic compounds that include:
 Triglycerides (simple lipids of fatty acid and glycerol)
 Waxes
 Phospholipid
 Steroids

II. Properties:
 Insoluble in water
 Soluble in inorganic solvents such as ether, chloroform and ethanol
 Identification test: lipids form a translucent spot on paper

III. Role of lipids in the human body:

 Are the principle form of energy storage
 Important source of energy
 Steroid and phospholipids constitute the main components of cell membrane
 Cholesterol is the starting material for the synthesis of steroid hormones and
vitamin D

IV. Fatty acids:

 Fatty acids are carboxylic acids that contain unbranched hydrocarbon chain 4 to 36
carbon atoms in length
 The hydrocarbon chain can be saturated (only single bonds) or unsaturated (one or
more double bond)
 The physical properties of fatty acid are determined by length of their chain and the
degree of unsaturation
 Fatty acids represented by the couple (a;b)
a: number of carbon atoms in the chain
b: number of double bonds in the hydrocarbon chain
Example: oleic acid (18; 1) means that it contains 18 carbon atoms and one
double bond in its hydrocarbon chain
 V. Fats and oils

Similarities:
 Organic compounds
 Density < 1 kg/l
 Insoluble in water and soluble in organic solvents
Differences:
Fats Oils
From animal origin From plant origin
Solids at room T liquids at room T
More saturated More unsaturated

VI. Classification of lipids:

A-Simple lipids:
Triglycerides are the most abundant simple lipids.

Esterification
1 molecule of glycerol + 3 molecule of fatty acid Hydrolysis 1 molecule of triglyceride + 3 molecules of water

The melting points of triglycerides depend on both the length of their chain and their
degree of unsaturation.
The melting point decrease with the increase with the degree of unsaturated and in the
length of the hydrocarbon chain.

B- Complex lipids:
They have the same structure as simple lipids except that one of the fatty acid residues
is replaced with other groups such as groups containing N, P, S and sugar. Example:
phospholipids.

VII. Cholesterol
Cholesterol is the most abundant steroid in the human body, it is not found in
plant.
 Chapter3: proteins

1-What are proteins?

 Proteins are polymers or macromolecules in which the monomer units are amino acids.
Two amino acids are joined together by peptide bond.
 All proteins contain carbon hydrogen oxygen and nitrogen.
 Protein differs from carbohydrates in that they contain nitrogen.
 Found much more in animals than in plants.

2-What is an amino acid?

 An amino acid is an organic compound that contains a carboxyl group (-COOH) and an
amino group (-NH3)
 The carbonyl group of one a.a. and the amino group of another a.a. are joined by peptide
bond to give dipeptide.
 a.a. in proteins are α a.a. (the amino group is connected to the carbon bearing the
carboxyl group)
 General formula: COOH

H2N CH R

3- Kinds of amino acids:

a) Essential: can’t be synthesized in human body, must be obtained from food.
b) Non-essential: our human can synthesize them.

3- Role of proteins in the human body:

Proteins serve structural as well as functional roles in the human body
 Enzyme activity: Enzymes are partly or totally made up from proteins.
All cellular chemical reactions are catalyzed by enzymes.
 Transport: hemoglobin is a protein that carry oxygen from lungs to the body cells.
 Contraction: actin and myosin in muscles
 Defense: antibodies and immunoglobulin
 Regulatory proteins: insulin
 Structural proteins: major components of tissues (har, skin, nails..)
 Chapter 4: Minerals and Vitamins

I- Vitamins:
 Definition:
Vitamins are organic compound that can’t be synthesized by the human body
but are essential for the proper functioning of the human body.

 Classification:

They are classified according to their solubility

 Hydro soluble vitamins (soluble in water) vitamin B and C these vitamins

are rapidly eliminated from the body in the urine (nontoxic in high doses)
 Fat soluble vitamins (soluble in fat) vitamins A,D,E,and K these vitamins
are stored in fatty tissue (toxic in case of high doses)
 Note: -Vitamins are not chemically similar
- Each vitamin has a specific function(s) in the body

II- Minerals:

 Definition:
Minerals are chemical element other than carbon, hydrogen, oxygen and
nitrogen needed for the proper functioning of the human body.

 Classification:
They are classified based on the quantity needed by the body
 Macro minerals: which are needed by the body in amount greater than
100 mg/day
Example:
calcium(Ca),phosphorous(P),magnesium(Mg),sodium(Na),potassium(K),c
hlorine(Cl)
 Trace minerals: are needed by the body in amount less than 20 mg/day
Example: fluorine (F), iron (Fe), copper (Cu), zinc (Zn), iodine (I)

 Role (in general):

 Structural role: formation of bones and teeth: (ex: Ca and P).
 Functional role: activating the enzyme system (ex: Cl).
 Controlling PH of blood.
  Constitute some compounds that have special physiological function (ex:
Fe in hemoglobin “Hb”).

Chapter 5: nutrition requirements

Energy requirements
Nutritional requirements
Growth and maintenance requirements

1) Energy requirements:
The energy requirements are converted mainly from carbohydrates (16 Kj/g), lipids (38 Kj/g)
and partly from proteins (17 Kj/g). Some of this energy is converted into mechanical energy
some into heat and some used to maintain metabolic processes.
2) Growth and maintains requirements:
These requirements are converted by proteins, when hydrolyzed provide the body with the
essential a.a. needed to build and replace tissue they include:
- Growth requirement: gaining weight (higher at young age).
- Gestation requirements: fetus growth during pregnancy.
- Lactation period: secretion of milk.

 Metabolism, anabolism and catabolism:

- Catabolism: large molecules are broken down into smaller ones.
Large molecules → small molecules + energy
- Anabolism: small molecules are joined together to form larger molecules.
Small molecules + energy → large molecule
- Metabolism: catabolic and anabolic reaction are called metabolism
 Energy production:
- Energy from carbohydrates:
Digestion Cellular
Carbohydrates Intestinal tract monosaccharides oxidation CO2 + H2O +
energy

- Energy from lipids:

Digestion
Fatty substances fatty acids + glycerol Oxidation CO2 + H2O +
energy
 - Energy from proteins:

Protein synthesis
proteins amino acids
oxidation (give energy)

In case of starvation :
proteins amino acids glucose + nitrogen (lost in urine) brain
energy

In general proteins are the building material for the human body: they can’t be transformed
into energy except in case of starvation.
 Chapter 6: The principal food

A. The principal food:

1) Cereals (wheat, rice and corn):

 They are rich in carbohydrates (60-70 %)
 The most important source of food for humans and animals

2) Milk and dairy products:

2.1. Cheese:
 Is prepared by precipitating the milk protein (casein), by adding rennet
which diminishes the PH of milk and coagulate the protein.
 It does not contain carbohydrates
2.2. Lactose intolerance:

 Lactose is found in milk

 In normal cases, lactose must be hydrolyzed in the small intestine by
lactase into glucose and galactose.
 Some people cannot digest lactose, (lactose intolerance) for the following
reasons:
 Genetic defect
 Physiological decline with age
 Injuries to the mucosa lining the intestine
 When the lactose remains in the intestine undigested, it may cause:
 Attraction of water causing fullness, nausea and diarrhea
 Bacterial fermentation of lactose which produces lactic acid and gas
adding to the discomfort.
3) Eggs:
 The white egg is composed basically of albumin, and traces of minerals
and vitamins.
 The yolk is composed of dispersed lipids and protein in water, the main
proteins are vitellin and vitellin.
 Yolk is insoluble in water.
 4) Fatty substances:
Rancidity of lipids:
 Oxidation (rancidity) of an unsaturated component (contains double bonds)
leads to the formation of aldehydes, ketones and carboxylic acids which
cause the unpleasant taste and objectionable odors.
 Polyunsaturated fatty acids are oxidized faster than mono-unsaturated fatty
acids.

5) Vegetables proteins:
 Cereals (wheat), some leguminous plants (soya beans, fava beans, and
peanuts), and potatoes are important sources of low cost proteins.
 Soya beans is particularly rich in proteins (also in lipids).

B. Food additives:
Definition:
Food additives are substances that are not consumed as food by themselves, but
are added to food for the following reasons:

 To preserve and maintain the nutritional quality of food

 To make food more attractive
1) Preservatives:
 They prevent or reduce the growth of microorganisms in food
 Example: benzoic acid which may be toxic at high levels of consumption
2) Antioxidants:
 They are used to prevent the rancidity (oxidation) of unsaturated fatty acids
 Kinds:
 Natural antioxidant: vitamin E and vitamin C
 Artificial antioxidants: BHA (butylated hydroxyanisole)
They may cause tumors and allergy
3) Sweetners:
 Sweetners are not sugar (carbohydrates)
 Kinds:
 Natural: aspartame which is dipeptide
 Synthetic: saccharine and cyclamates
4) Colorants:
 Colorants are added to food to make them attractive or to replace color lost
during processing
 They may have allergic effect
 Kinds:
 Natural colorants: riboflavin (vitamin B2), chlorophyll
 Synthetic: tartazine
5) Emulsifiers, stabilizers and thickners:
 Emulsifiers and stabilizers are used to stabilize food emulsions
 Thickners are utilized to reinforce food texture
6) Miscellaneous food additives:
There are many other types of additives such as flavors, flavor enhancements,
additives for PH control...
 Chapter 7: Food diet

1) Energy requirements for human:

Energy is required by the human body for basal metabolism and physical activity.

A. Basal metabolism:
Definition: it is the energy needed for the basic metabolism processes which
keep the body live; that is to keep the heart beating and the lungs functioning.
B. Physical activity:
Energy is also needed for the various physical (muscular) activities done in
our daily life such as walking, sitting, standing, running…
2) What is a balanced diet?
A balanced diet is a diet that is balanced nutritionally; that is containing the
following groups each day:
Group 1: meat, fish and eggs:
Nutrients for growth and maintenance: proteins, iron, phosphorus
Suppliers of energy: lipids
Regulatory nutrients: vitamins

Group 2: milk and dairy products:

Nutrients for growth and maintenance: proteins, calcium

Suppliers of energy: lipids and carbohydrates
Regulatory nutrients: vitamins
Group 3: fatty substances (oil, butter…)
Nutrients for growth and maintenance: none
Suppliers of energy: lipids
Regulatory nutrients: fat soluble vitamins
Group 4: cereals and leguminous grain (rice, lentils…)
Nutrients for growth and maintenance: proteins
Suppliers of energy: carbohydrates
Regulatory nutrients: minerals
Group 5: fruits and vegetables:
Nutrients for growth and maintenance: calcium
Suppliers of energy: none
Regulatory nutrients: vitamins and minerals
 Group 6: beverages:
Nutrients for growth and maintenance: calcium
Suppliers of energy: carbohydrates
Regulatory nutrients: vitamins and minerals

3) Effect of cooking on nutrition value of food:

A. Effect of cooking on carbohydrate:
Cooking starch facilitates its digestibility
B. Effect of cooking on proteins:
Cooking denature proteins and improves their digestibility; it is easier for the
digestive enzymes to work on denatured proteins.
C. Effect of cooking on lipids:
Excessive heating causes fats and oils to oxidize because of the unsaturated
fatty acids, this make fat inconsumable as a result of formation of polymers
and some toxic compounds.

Heating
Fats and oils (unsaturated fatty acids) polymers +
toxic compounds Oxidation

D. Effect of cooking on minerals and vitamins:

Treatment of food with water leads to a great loss of minerals and water
soluble (hydro-soluble) vitamins.
Vitamins are also thermos sensitive (vitamins A and C) and are destroyed at
high temperature in the presence of oxygen.
 Unit 2: current medical drugs
Chapter 10: current medical drugs.

1. What are medical drugs:

1.1 Definition:
Medical drugs are substances used for treating diseases or relieving pain.

1.2 Sources:
 Some are synthesized (Panadol, aspirin…)
 Some are obtained by fermentation or by microbial culture (antibiotics)
 Some are obtained from animal source (insulin, hormones…)
 Some are obtained from plants (opium)

1.3 Conditions:
 A drug must not be toxic
 Has no side effect
 The range between the therapeutic and toxic doses must be wide
 The effectiveness of a drug should not be diminished by substances present in
the human body (gastric acid)
 A drug must be administered in reasonable size
 Be stable and inexpensive.

2. Drug formulation and drug additives:

 Drugs can be formulated into tablets, capsules, liquid, sprays, ointments,
suppositories
 Drugs are composed of active ingredients and inert ingredients (additives):
Active ingredient is the same for different brands
Inert ingredients (additives) may vary with the brand.
 Role of additives:
Serve as fillers, binders and coating/ adjust the size, shape, flavor and
appearance.
 3. Classification of drugs: (according to their pharmaceutical activity)

3.1 Analgesics:
Def: are substances that reduce or eliminate pain.

Analgesics are divided into 3 main groups:

 Narcotic: are used to reduce or eliminate moderate and sever pain. (ex:
morphine and codeine)
 Anti-pyretic: are used to lower fever. (ex: aspirin, Panadol)
 Anti-rheumatics: are used to reduce inflammation of muscles and joints.
(ex: aspirin)

Comparison between aspirin and Panadol:

Generic name Trade name Pharmaceutical action Side effects

Aspirin aspirin Analgesic (anti-pyretic, - Cause severe damage to stomach
Anti-rheumatic) - Inhibits the formation of blood
platelets.
paracetamol Panadol Analgesic (anti-pyretic) Affect the liver in high doses.

3.2 Anesthetics:
Def: are substances that produce anesthesia, a state of being unable to feel pain, heat
and cold.

Classification:

 Local anesthetic:
Are used to provide temporary pain relief on localized regions of the body.
They act directly on the nerve cells to block their ability to transmit
impulses.
They are used for minor surgery.
Ex: ethyl chloride, which is an example of local anesthetic used as a spray,
it evaporates quickly when it is sprayed on the surface of the skin, and it
freezes the tissues near the surface making them insensitive to pain.
Side effects: tremor, restlessness, drowsiness.

 General anesthetic:
These are reversible depressants of the central nervous system that produce
a loss of sensation and consciousness.
 Classification:
 Inhaled anesthetic: induce unconsciousness with few minutes
after inhalation of the drug (ex: nitrous oxide).
 Intravenous anesthetic: are administered by injection (ex:
penthiobarbital).

Side effects of general anesthetic:

 Depression of respiratory drive, depression in the cardiovascular
function, nausea and vomiting.
 An overdose my lead to coma and death.

3.3 Anti-acids:
Def: are substances used to treat problems caused by excessive gastric acid
secretions (HCl).

3.4Anti-inflammatory:
Def: are substances that reduce inflammation. Inflammations is the reaction of
tissues to injuries, it constitutes a reaction of defense of the organism against
external aggressions (foreign bodies, microorganisms, surgery…)

Classification:

 Steroidal anti-inflammatory agents: (based on steroid nucleus)

ex: cortisone, cortisol, hydrocortisone.
Side effects: fluid retention, unwanted hair, mental depression.
Overdose effects: overweight and obesity.

 Non-steroidal inflammatory agents:

ex:

Generic name Trade name Side effects

aspirin Aspirin Stomach distress, nausea

Ibuprofen Advil Nausea, vomiting, diarrhea,
anemia
diclofenac Voltarene Nausea, vomiting, diarrhea,
anemia
 3.5 Antibiotics:
Def: are chemicals produced by one microorganism (natural antibiotics), or by
chemical synthesis to kill or inhibit the growth of other microorganisms.

 Antibiotics that kill bacteria are called bactericidal.

 Antibiotics that kill fungi are called fungicidal.
Classification:

 Broad spectrum antibiotics:

Effective against a wide range of bacteria.
Used when the invading microorganism is unknown.
Their use should be restricted because they may kill some beneficial
bacteria.
 Narrow spectrum antibiotics:
Effective against a specific microorganism.
Effective when the invading microorganism is identified.

Bacteria resistance to antibiotics:

Bacteria may develop resistance to antibiotics, it can be natural or acquired.

Bacteria resistance to antibiotics can be explained by different mechanisms:

 Some resistant bacteria have the capacity to produce enzyme, which

modify or break the molecule of antibiotics.
 Some bacteria are capable of growing in the presence of unmodified
antibiotics.
- They acquire a state of tolerance.
- They change their active site.
Overdose effects: dysfunction of the brain, troubles in perception, intense
contractions in heart muscles and in limb muscles.
 3.6 tranquilizers:
Def: are substances used to sedate without inducing sleep. They are used to relieve
anxiety, excitement and restlessness.

Overdose effects: state of intoxication (drunkenness), drowsiness, coma depression

in respiratory drive, muscle rigidity and death.

3.7 Anti-depressants:
Def: are drugs used for treating depression.

Symptoms of depression:

Continuous sadness, loss of interest and pleasure in activities, crying spells, feeling
guilt, worthless.

Overdose effects: unconsciousness, coma, death.