2. BIOMOLECULES and the CELL
The cell speaks:
“I am the unit of biological activity;
Organized into subcellular organelles;
Assigned to each are specific duties;
Thus, I truly represent life!”
3. The living matter is composed of mainly six elements:
carbon
hydrogen
oxygen
nitrogen
phosphorous
sulfur
These elements together constitute about 90% of the dry
weight of the human body.
Several other functionally important elements are also found
in the cells. It includes:
Ca K Na Cl Mg Fe Cu
Co I Zn F Mo Se
4. Carbon - a unique element of life
Carbon is the most predominant and versatile element of life.
It possesses a unique property to form infinite number of
compounds.
This is attributed to the ability of carbon to form stable
covalent bonds and C - C chains of unlimited length.
It is estimated that about 90% of compounds found in
living system invariably contain carbon.
5. The Major Complex Biomolecules of Cells
Biomolecule
Building Block
(repeating unit) Major Functions
1. Protein Amino Acids Fundamental basis of structure and
function of cell (static and dynamic
functions).
2. Deoxyribonucleic
acid (DNA)
Deoxyribonucleotides Repository of hereditary information.
3. Ribonucleic acid
(RNA)
Ribonucleotides
Essentially required for protein
biosynthesis.
4. Polysaccharide
(glycogen)
Monosaccharides
(glucose)
Storage form of energy to meet term
demands.
5. Lipids Fatty acids, glycerol Storage form of energy to meet long
term demands; structural components
of membranes.
6. Chemical Composition of a Normal Man
(weight 65kg)
Constituent Percent(%) Weight (kg)
Water 61.6 40
Protein
17.0 11
Lipid
13.8 9
Carbohydrate 1.5 1
Minerals
6.1 4
7. THE CELL
- is the structural and functional unit of life.
- it may be also regarded as the basic unit of biological activity.
Prokaryotic and eukaryotic cells
The cells of the living kingdom may be divided into two categories:
1.Prokaryotes - lack a well defined nucleus and possess relatively simple
structure. These include the various bacteria.
2. Eukaryotes - possess a well defined nucleus and are more complex in their structure and
function. The higher organisms (animals and plants) are composed
of eukaryotic cells.
8. Comparison between prokaryotic and eukaryotic cells
Characteristics Prokaryotic Cell Eukaryotic Cell
1. Size Small (generally 1 - 10 μm) Large (generally 10 - 100 μm)
2. Cell membrane Cell is enveloped by a rigid wall Cell is enveloped by a flexible plasma membrane
3. Sub - cellular
organelles
Absent
Distinct organelles are found (e.g.,
mitochondria, nucleus, lysosomes)
4. Nucleus
Not well defined;DNA is found as
nucleoid,histones are absent
Nucleus is well defined, surrounded by a
membrane;DNA is associated with histones
5. Energy metabolism
Mitochondria absent, enzymes of
energy metabolism bound to
membrane
Enzymes of energy metabolism are located in
mitochondria
6. Cell division Usually fission and no mitosis Mitosis
7. Cytoplasm Organelles and cytoskeleton absent
Contains organelles and cytoskeleton (a
network of tubules and filaments)
9. BIOCHEMICAL/CLINICAL CONCEPTS
•A living cell is a true representative of life with its own
organization and specialized functions.
• Accumulation of lipofuscin, a pigment rich in lipids and
proteins, in the cell has been implicated in ageing process.
• Leakage of lysosomal enzymes into the cell degrades
several functional macromolecules and this may lead to
certain disorders (e.g. anthritis)
10. SUMMARY
1. Life is composed of lifeless chemical molecules. The
complex biomolecules, proteins, nucleic acids (DNA and
RNA), polysaccharides and lipids are formed by the
monomeric units amino acids, nucleotides, monosaccharides
and fatty acids, respectively.
2. The cell is the structural and functional unit of life. The
eukaryotic cell consists of well defined subcellular organelles,
enveloped in a plasma membrane.
3. The nucleus contains DNA, the repository of genetic
information. DNA, in association with proteins (histones), forms
nucleosomes which, in turn, make up the chromosomes.
11. 4. The mitochondria are the centres for energy metabolism. Thy
are the principal producers of ATP which is exported to all parts
of the cell to provide energy for cellular work.
5. Endopalsmic reticulum (ER) is the netweok of membrane
enclosed spaces that extends throughout the cytoplasm. ER
studded with ribosomes, the factories of protein
biosynthesis, is referred to as rough ER. Golgi apparatus are
a cluster of membrane vesicles to which the newly
synthesized proteins are handed over for further processing
and export.
12. 6. Lysosomes are the digestive bodies of the cell, actively
involved in the degradation of cellular compounds.
Peroxisomes contain the enzyme catalase that protects the
cell from the toxic effects of H2O2 . The cellular ground
matrix is referred to as cytosol which, in fact, is
composed of a network of protein filaments, the
cytoskeleton.
13. Primary Recommendations to promote Good Health through
Proper Nutrition
1. Eat a variety of foods every day.
2. Breast - feed infants exclusively from birth to 4-6
months, and hen, give appropriate foods while continuing breast -feeding.
3. Maintain children’s normal growth through proper diet and monitor
their growth regularly.
4. Consume fish, lean meat, poultry or dried beans.
5. Eat more vegetables, fruits and root crops.
6. Eat foods cooked in edible oil/cooking oil daily.
7. Consume milk, milk products or other calcium - rich foods
such as small fish and dark green leafy vegetables everyday.
14. 8. Use iodized salt, but avoid excessive intake of salty foods.
9. Eat clean or safe food.
10. For healthy lifestyle and good nutrition, exercise regularly,
do not smoke, and avoid drinking alcoholic beverages.
15. Nutritional Status or Nutriture
- condition of health of body as a result of ingestion and
utilization of food.
Classification:
Normal Nutriture = + or - 10%
of Desirable Ideal Body Weigth
Overweight = Actual Weight is 11 to 20% above the DBW.
Obese = Actual weight is more than 20% of the DBW.
Undernutrition - 1st degree
- actual weight is 75.90% of DBW.
19. What is Energy?
- Energy is the capacity to do work.
- Commonly expressed in Kilocalories or cal Kilojoules
Components of Energy Requirement
Basal
metabolism
Thermic Effect of
Exercise (Physical
Activity)
Thermic effect of
food
20. Energy
1. Basal metabolic Rate (BMR)
Energy needed to maintain life when a body is at complete
rest after a 12 hour fast.
2. Basal Metabolism
Energy expended to maintain metabolism during
complete physical & mental rest
21. Components of Energy Expenditure
Basal energy is needed to:
Heat or cool the body normal organ functions maintenance of tissues
metabolic homeostasis
Computation of BMR
Krause and Mahan Method ( for normal weight and height
Adult Male = 1 kcal E/kg desirable body wt./hr.
Female = 0.9 kcal E/kg desirable body wt/hr.
BMR = 1kcal x body weight (kg) x 24 hrs.
22. Sample Calculation:
1. For a 24 year old Filipino who is confined
at the hospital and is 5’2” tall
DBW = 157 cm - 100 = 57 kg
- 5.7 = 51 kg.
Thanhausser’s Formula:
Height(cm) - 100 = weight(kg) for Western Standard
(Deduct 10% for Filipinos)
23. 1 inch = 2.54cm.
62 inch x 2.54 cm = 157.4 cm
For a 29 year old Filipino and is 5’2” tall
5 x 12 = 60 inch + 2 = 62 inch
62 x 2.54cm = 157.48 cm.
DBW = 157 cm - 100 = 57 - 5.7
= 51.3 or 51 kg.
BMR = 1cal x w + kg x 24 hrs.
= 1 x 51 x 24
= 1224 cal.
24. Basal Metabolic Rate Determinants
•Body size
•Sex
•body Temperature
•State of Nutrition/body condition
•climate
•Relaxation of muscle tension
•hormone secretions
•hyperthyroidism
•hypothyroidism
25. Water, bone and fat do not actively participate in energy metabolism
since the seat of energy exchange is in the active protoplasm or in the
muscles.
•Thus, women usually have a lower basal metabolic rate than men.
•Non - athletes lower than athletes by about 5%
•The skeletal muscles expend almost 1/5 of the resting metabolism.
26. Women have 6 - 10% lower basal metabolic rates than men
because of sex differences in body mass and hormones.
Women usually have more adipose tissue.
Adipose tissue is much less metabolically active than in lean tissue
SEX
27. BODY SIZE
A tall, lean man will have higher basal metabolism than a stout,
short person of the same weight because of the greater surface
in the former.
BODY TEMPERATURE
ºTemp as in fever
•will cause 13% rise for each degree above 37 ºC.
º Temp
•shivering results and as response,
BMR increases
28. GROWTH
The growth hormone stimulates cell metabolism and
raises BMR 15% - 20%
Thus, the BMR slowly rises during the first 5 years of life,
levels off somewhat, rises again just before and during
puberty, and then gradually declines into old age.
29. CLIMATE
The adjustment is based more on the amount of
physical activity performed on account of climate.
AGE
BMR declines during old age due to the slowing
down of body processes.
There is a decrease of 5% for each decade between
40 - 58 years.
For decades 60 - 69 and 70 and above,
the decrement is increased to 10% per decade.
30. PREGNANCY AND LACTATION
During pregnancy and lactation, the BMR is increased by 20 - 25%
because of the development of the fetus and placenta or an increase in
metabolic activity of the maternal tissues.
Energy expended during lactation.
