HUMAN NUTRITION AND DIET
BIOLOGICAL MOLECULES
Biological molecules are large molecules necessary for life , that are built from
smaller organic molecules . There are four major classes of biological
macromolecules. These are ;
1. Carbohydrate
2. Lipids
3.Protein
4. Nucleic acid (DNA)
CARBOHYDRATES
 Carbohydrate is made up of carbon, hydrogen and oxygen
 Types of Carbohydrates
 1.Monosaccharide ; This sugar contains a single ring. They are the simplest
sugar e.g glucose ,fructose and galactose. They have a general formula of C6
H12 O6
Sub-unit – Glucose
GLUCOSE
2. Disaccharide (Reducing sugar) ; These contain two carbon rings in their molecules
and are represented with the formula C12 H22 011 e.g
(i) Maltose = glucose and glucose
(ii) Sucrose = glucose and fructose
(iii) Lactose = glucose and glactose
3. Polysaccharide ; are made of long chains of monomers (simple sugar) held
together by chemical bond . The general formula is (C6 H10 O5)n e.g starch, cellulose
, glycogen .Polysaccharide are not soluble in water
IMPORTANCE OF CARBOHYDRATES
 Provides energy
FATS AND OILS
Fats and oils are known as lipids .They contain high proportion of carbon, hydrogen
but very little oxygen. Fats are solid .When fats are liquid they are known as oils.
A molecule of fat or oil is made up of three molecules of fatty acid and one
molecule of glycerol e.g olive oil, cold liver oil , waxes , melon oil, butter e.t.c
Sub-unit- Fatty acid and glycerol
IMPORTANCE OF FATS AND OIL
1. Formation of cell membrane and nuclear membrane
2. Provides more energy than carbohydrates
3. Serves as solvent for some vitamins
4. It protects vital organs
5. It smoothens the skin
PROTEINS
Protein is composed of carbon , hydrogen , oxygen , nitrogen and sometimes
phosphorus and sulphur .Their molecules are made up of long chains of simpler
chemicals called amino acids . There are about 20 different amino acids in
animal protein and each type has its amino acid arranged in a special sequence
e.g enzymes , muscle, haemoglobin, cell membranes, meat ,fish , beans
,groundnut ,soyabeans e.t.c
Break down of protein during digestion takes place in the following stages
Protein – Peptones – Polypeptides – Amino acid
Sub unit – Amino acids
Importance of protein
1. For body building
2. For growth
3. For repair of damaged tissues
4. For the supply of the necessary amino acids
5. For formation of hormones , enzymes, antibodies and forming of fibrinogen
necessary for blood clotting
PROTEIN SHAPE
There are thousands of different proteins in the human body and other
organisms. Different sequence of amino acids give different shapes to protein
molecules.
For example:
- Enzymes have an area in them known as the active site, This is important as this
is the place where another molecule fits into the enzyme in order for a reaction to
take place
- If the shape of the active site does not match the shape of the molecule that fits
into it, the reaction will not take place
- Every enzyme has a different shaped active site
- Antibodies are proteins produced by certain types of white blood cell to attach to
antigens on the surface if the pathogens
- The shape of the antibody must match the shape of the antigen so that it can
attach to it and signal it for destruction
- In this way every protein has a unique 3- D shaped that enables it to carry out its
function
STRUCTURE OF DNA
 A DNA is made up of long chains of nucleotides , formed into two
strands(double helix) .
 Each nucleotide is made up of ;
1) Deoxyribose – a 5-carbon sugar molecule
2) Phosphate group
3) An organic base which is either Adenine (A), Thymine (T) , Guanine (G) or
Cytosine (C).Cross-links between the strands are formed by pair of bases
 The bases always pair up in the same way : Adenine (A) with Thymine (T) and
Guanine (G) with Cytosine (C)
Draw the above structure
STRUCTURE OF DNA
The size of the DNA molecules makes sure that A always pair with T and C with G.
They are complementary strands .
The double strands is twisted to make a helix .
Scientist that are involved in the discovery of DNA ;
1. Crick and Watson
2. Rosalind Franklin
ROLE OF mRNA IN PROTEIN SYNTHESIS
 mRNA carries a copy of the gene /DNA/ base pair sequence
 mRNA travel from the nucleus to the cytoplasm/ribosome . The order of
amino acids depends on the sequence of bases in mRNA
MINERAL SALT
Mineral salts are required for metabolic activities within the body. They are taken
in minute quantity through the food we eat. Lack of these mineral salts will result
in nutritional deficiency.Mineral salt include Calcium , Phosphorus , Magnesium ,
Potassium, Suphur , Sodium , Chlorine , Iron , Iodine , Msgaaese e.t.c
THE SOURCE, FUNCTION AND DEFICIENCY SYMPTOMS OF SOME MINERAL SALTS
Mineral
Calcium
Phosphorus
Iron
Sodium and
Chlorine
Iodine
VITAMINS
Sources
Milk, Cheese, Egg,
Fish
Functions
- Bone and teeth formation
and development
- For blood clotting
- Normal functioning of
heart , Nervous system and
muscles
Milk , Cheese , Egg , - For strong development of
Fish and Wheat
teeth and bones
- Forms part of DNA and
RNA
- For respiration
Eggs , Liver ,
- Formation of haemoglobin
kidneys , Beans ,
in red blood cells
Vegetables
Table salt , Fish ,
- Transmission of nervous
Friuts
impulses
- Maintenance of osmotic
balance of the cells
Seafoods
- Required by the thyroid
gland to make thyroxine
Deficiency Symptoms
-Rickets
- Tooth decay
- Osteomalacia
- Ricket
- Tooth decay
- Osteomalacia
- Anaemia
- Dehydration
- Muscle cramp
- Goitre
Vitamins are inorganic compounds and they are biocatalyst i.e they promote
chemical reactions in the body .
Groups of vitamins : i. Fat soluble vitamins e.g Vitamins A,D,E and K
Ii. Water soluble vitamins e.g Vitamins B- Complex and Vitamin C
Vitamins required by humans
Vitamin
Vitamin A
(Retinol )
Vitamin B1
(Thamine)
Vitamin B2
( Riboflavin)
Vitamin B3
(Niacin )
Source
Liver, eggs, fish ,
milk , palm oil ,
fresh vegetables
Yeast , unpolished
rice , milk, beans ,
palmwine
Function
- For proper vision of the eye
- Required for normal growth
Deficiency Symptoms
- Night blindness
- Skin becomes flaky
- needed for synthesis of coenzymes
- involved in cellular
respiration
- Formation of co-enzymes
involved in cellular respiration
- Beriberi ( a condition
due to loss of appetite
, weight, tiredness and
paralysis)
- Cracking of the skin
around the corners of
nose , mouth and eyes
- Pellagra ( Scally
pigmented skin , sore
mouth and tongue ,
nervous disorder )
- Disorder of nervous
system and gut
Yeast, Soyabeans ,
egg , milk , green
vegetables
Yeast , beans , milk - needed for cellular
, palmwine , yam , respiration
vegetables
Vitamin B5
( Pantothenic )
Yeast, egg , rice
bran
- Formation of co-enzymes
involved in cellular respiration
Vitamin B6
( Pyridoxine )
Yeast , egg , cereal
Vitamin B12
Kidney, liver , fish ,
milk
- Formation of enzymes
- Anaemia
involved in synthesis of amino- - Diarrhoea
acids
-Formation of red blood cells
- Pernicious aneamia
( Cyanocobalamin)
Vitamin C
Fresh fruits e.g
(Ascorbic acid )
orange and green
vegetables
Vitamin D
Fish , milk , egg,
(Calciferol )
liver , formed in
the skin by sunlight
- aids wound healing
- helps to resist infection
- Scurvy
- needed for strong bone and
teeth formation and
development
- Ricket
- softening of bones in
adult
Vitamin E
(tecopherol)
Vitamin K
Green vegetables ,
egge , butter , liver
Fresh green
vegetables , liver
- promotion of fertility in
animals
- aids clotting of blood
-Sterility and
premature abortion
-Haemorrhages i.e
inability of blood to
clot in time
WATER
Water is composed of two elements: Hydrogen and oxygen.
IMPORTANCE OF WATER
1. Aids excretion
2. Acts as solvent for soluble substances in digestion
3. It is necessary for the digestion of food
4. It can be used for the maintenance of body temperature
5. Acts as a medium of transportation for nutrients
6. It helps to maintain the osmotic content of the body tissues
ROUGHAGES
Roughages consists of indigestible fibre materials derived from vegetables, fruit,
carbohydrates and proteins
IMPORTANCE OF ROUGHAGES
1. Stimulates bowel movement / peristalsis
2. Reduces blodd cholesterol / bowel cancer / Gall stones
3. They do not contribute to weight gain / High blood sugar
4. It releases glucose slowly
5. It prevents constipation / Add digestion
FOOD TEST
TEST FOR VITAMIN C
BALANCED DIET
Balanced diet is a diet containing all nutrients/components in correct proportions
to maintain health and appropriate energy requirements.Balanced diet
requirements varies according to age/sex/ lifestyle/pregnancy.
IMPORTANCE OF BAKANCED DIET
1. It encourages growth and normal development of the body
2. It increases resistant to diseases
3. It provides energy required for normal activities
4. Balanced diet prevents malnutrition / deficiency disease
Lack of some food substance e.g protein in a diet can cause a nutritional disease
called kwashiorkor in children and Marasmus as a result of early weaning is
characterized by:
a. Retarded growth
b. Loss of weight
c. Diarrhoea
d. Fatigue
e. Muscle wasting
f. Pale body
g. Change in the colour of the hair , the hair becomes reddish brown
Don’t draw