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search for better health
part 1
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Contextual Outline
When physiological processes malfunction, the body tries to repair the damage. The process
is similar in all living things and it is only when the process fails to contain the damage that
disease can be recognised.
Humans have long recognised the symptoms of disease both in themselves and the animals
and plants around them. Since the beginnings of recorded history, they have noted the signs
that reveal that the body is malfunctioning. Increasing understanding of the causes of disease
together with accompanying advances in technology has changed approaches to treatment
and management of disease.
The search for measures to treat and manage diseases of humans and other organisms
continues and this search is paralleled by continued refinements in technology.
1. What is a healthy organism?

discuss the difficulties of defining the terms ‘health’ and ‘disease’
Health can be defined as the absence of disease. This has been modified by the World
Health Organisation (WHO) give the definition as “a state of complete physical, mental
and social well-being and not merely the absence of disease”.
It does not mean just having a ‘bad hair day’.
Disease can be defined as “any condition that disturbs the normal functioning of the
body”.
Problems with defining Health
Different people have different levels of ‘wellbeing’ when they say they are healthy.
Example: A ‘fit’ person will say that they are healthy if they currently do not have a
‘disease’.
In contrast a person with a chronic disease may say that they are healthy if the
symptoms are not too bad that day.
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Problems with defining Disease
There can be some confusion between the definition disease and disability e.g. health
reports will often say that arthritis is a disabling condition rather than a disease.
Pregnancy can often adversely affect the functioning of the mother’s body but most
people would not call pregnancy a disease.

outline how the function of genes, mitosis, cell differentiation and specialisation assist in the
maintenance of health
The maintenance of health in an individual is assisted by the maintenance and
repair of the body’s cells and tissues.
Gene Functioning
The function of genes is to ensure that the correct proteins are produced in a cell to
enable all the cellular processes to continue.
If there is a malfunction in a gene then a metabolic pathway may be disrupted and
the health of the organisms would be affected.
Mitosis
Mitosis is the process of cell division where one cell replicates to form two
identical daughter cells.
Mitosis enables genetic information to be copied correctly when new cells are
formed.
The ability to produce new cells enables an organism to grow and replace and
repair worn out or damaged cells.
Changes or mutations in the genetic material may occur during the life of an
organism.
If there is a mistake in the mitotic division of the zygote or early stage embryo
this may result in trisomy (three copies of a chromosome) or monosomy (just one
copy). The mitotic error may affect the health of the entire organism. The
symptoms of these conditions depend on the chromosomes affected.
Healthy cells that are growing and dividing normally have their cell cycle
regulated carefully.
DNA repair genes – ensure DNA is accurately copies Proto-oncogenes &
tumour suppressor genes – play a complementary role in regulating the cell
cycle.
Proto-oncogenes produce proteins that stimulate cell growth and cell division
Tumour suppressor genes – produce proteins that slow down or stop cell
growth and cell division.
In a healthy cell this balance results in the control of the cell cycle.
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If Control Breaks Down!!!!!
Control can break down if proto-oncogenes or tumour suppressor genes are
themselves damaged or mutated.
Example: Mutated proto-oncogenes are called oncogenes.
Oncogenes cause uncontrolled cell replication.
When tumour suppressor genes mutate they lose their ability to control cell
division. The rate of cell division increases and uncontrolled cell growth occurs.
Tumour suppressor genes tend to be recessive. Both alleles must mutate before
rapid growth occurs.
A single mutated suppressor gene may be inherited but a second mutation needs
to occur for uncontrolled growth and a tumour develop.
Cell Specialisation accompanies cell Differentiation:
Cell differentiation is a process undergone by cells that are formed after mitosis.
Each cell has the genetic information to produce all cell types.
Each cell however normally differentiates to become a specialized cell, with a
specialized structure and function.
Unspecialized cells become tumors.
Specialized cells have a specific role in maintaining the health of an organism.
Example – there are specialized blood cells that produce antibodies to attack
disease causing micro-organisms.
Different cells become specialized for different functions within a multicellular
organism.
Mammals have different tissues such as blood, nerve, bone and muscles. These
tissues work together in a healthy body in a controlled and coordinated way.
Healthy cells can adapt to change.
Changes can occur in the internal environment – for example the blood calcium
level can fall. As a result the bones may release calcium into the blood resulting in
the softening of the bones to prevent a more serious consequence of low calcium
levels in the body.
Processes like these occur as a result of healthy functioning of genes, the
production of perfect copies of genetic material and their expression in the process
of cell differentiation and cell specialization.
If these processes are impaired, the organism will not be healthy.
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
use available evidence to analyse the links between gene expression and maintenance
and repair of body tissues
Gene expression refers to the transfer of information from a gene to produce a
protein or RNA. If you cut yourself, the genetic code contained in all your cells is
used to form the new tissue to repair the damage from the cut.
Not all the cells in your body are the same. They have specialised for different
functions; muscle cells, nerve cells and blood cells etc.
Every cell in the body contains in its chromosomes, ALL the genes needed to
differentiate into all the special cells of the body that have specific functions and
traits. For a cell to differentiate the gene for that purpose must be ‘switched on’.
Genes are the units of inheritance. They control the process of protein synthesis.
They assist the maintenance of health by regulating the cell cycle and limiting the
growth and reproduction of cells.
Mitosis is cell division that produces identical cells. These cells are important for
growth and reproduction. Each day millions of cells die and are replaced by the
process of mitosis.
Cell differentiation is the process undergone by the cells that are formed after
mitosis. Each cell has the genetic information necessary to produce all types of
cells. However, each cell normally differentiates to become a specialised cell, with
a specialised structure and function.
Differentiation is essential for the correct functioning of the body, and therefore
health. If a muscle cells switched on the genes for a blood cell it would no longer
function properly. This could cause a loss of body function, and therefore, a lack of
good health.
Undifferentiated cells form tumors.
Many types of cells have specialised roles in maintaining the health of an
organism. For example, there are specialised blood cells that produce antibodies to
attack a disease causing micro-organism.
Contributions from
are acknowledge in this unit of work.
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