NUTRITIONAL BIO-CHEMISTRY-ANSx - A Distance EDU College

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20 Φεβ 2013 (πριν από 4 χρόνια και 5 μήνες)

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5 MARKS:

1. Nutrition

Nutrition

(also called
nourishment

or
aliment
) is the provision, to
cells

and
organisms
, of the
materials necessary (in the form of food) to support
life
. Many common health problems can be
prevented or alleviated with a
healthy diet
.

The
diet

of an organism is what it eats, which is largely determined by the perceived
palatability

of foods.
Dietitians

are
health professionals

who sp
ecialize in
human nutrition
, meal planning,
economics, and preparation. They are trained to provide safe, evidence
-
based dietary advice and
management to individuals (in health and disease), as well as to institutions. Clinical
nutritionists

are health professionals who focus more specifically on the role of nutrition in chronic disease,
including possible prevention or remediation by addressing nutritional deficiencies before
resorting to drugs. While govern
ment regulation of the use of this professional title is less
universal than for "dietician", the field is supported by many high
-
level academic programs, up
to and including the Doctoral level, and has its own voluntary certification board,
[1]

professional
associations, and peer
-
reviewed journals, e.g. the
American Society fo
r Nutrition

and the
American Journal of Clinical Nutrition
.

A poor diet may have an injurious impact on health, causing deficien
cy diseases such as
scurvy
[2]

and
kwashiorkor
;
[3]

health
-
threatening conditions like
obesity
[4]
[5]

and
metabolic syndrome
;
[6]

and
such common chronic systemic diseases as
cardiovascular disease
,
[7]
[8]

diabetes
,
[9]
[10]

and
osteoporosis
.


2. Nutrients

There are six major classes of nutrients:
carbohydrates
,
fats
,
minerals
,
p
rotein
,
vitamins
, and
water
.

These nutrient classes can be categorized as either
macronutrients

(needed in relatively large
amounts) or
micronutrients

(needed in smaller quantities). The macronutrients include
carbohydrates (inc
luding
fiber
), fats, protein, and water. The micronutrients are minerals and
vitamins.

The macronutrients (excluding fiber and water) provide structural material (amino acids from
which proteins are built, and lipids from which cell membranes and some signaling molecules
are built) and
energy
. Some of the structural material can be used to generate energy internally,
and in either case it is measured in
Joules

or
kilocalories

(often called "Calories" and written
with a capital
C

to distinguish them from little 'c' calories). Carbohydrates and proteins provide
17

kJ approximately (4

kcal) of energy per gram, while fats provide 37

kJ (9

kcal)
per gram.,
[17]

though the net energy from either depends on such factors as absorption and digestive effort,
which vary substantially from instance to instance. Vitamins, miner
als, fiber, and water do not
provide energy, but are required for other reasons. A third class of dietary material, fiber (i.e.,
non
-
digestible material such as cellulose), is also required,
[
citation needed
]

for both mechanical and
biochemical reasons, although the exact reasons remain unclear.

Other micronutrients include
antioxidant
s

and
phytochemicals
, which are said to influence (or
protect) some body systems. Their necessity is not as well established as in the case of, for
instance, vitamins.

Most foods

contain a mix of some or all of the nutrient classes, together with other substances,
such as toxins of various sorts. Some nutrients can be stored internally (e.g., the fat soluble
vitamins), while others are required more or less continuously. Poor heal
th can be caused by a
lack of required nutrients or, in extreme cases, too much of a required nutrient. For example,
both salt and water (both absolutely required) will cause illness or even death in excessive
amounts.
[18]
[19]

3. Other nutrients

Other micronutrients include antioxidants and phytochemicals
. These substances are generally
more recent discoveries that have not yet been recognized as vitamins or as required.
Phytochemicals may act as antioxidants, but not all phytochemicals are antioxidants.
[
citation needed
]

Antioxidants

As cellular
metabolism
/energy production requires oxygen, potentially damaging (e.g.
mutation

causing) compounds known as
free radicals

can form. Most of these are oxidizers (i.e. acceptors
of electrons) and some rea
ct very strongly. For the continued normal cellular maintenance,
growth, and division, these free radicals must be sufficiently neutralized by antioxidant
compounds. Recently, some researchers suggested an interesting theory of
evolution of dietary
antioxidants
. Some are produced by the human body with adequate
precursors

(
glutathione
,
Vitamin C
), and those the body cannot produce may only be obtained in
the diet via direct
sources (Vitamin C in humans,
Vitamin A
,
Vitamin K
) or produced by the body from other
compounds

(
Beta
-
carotene

converted to Vitamin A by the body,
Vitamin D

synthesized from
cholesterol

by
sunlight
).

Phytochemicals

A growing area of interest is the effect upon human health of trace chemicals, collectively called
phytochemicals
. These nutrients are typically found in edible plants, especially colorful fruits
and vegetables, but also other organisms including seafood, algae, and fungi. The e
ffects of
phytochemicals increasingly survive rigorous testing by prominent health organizations.
[
citation
needed
]

One of the principal classes of phytoch
emicals are
polyphenol antioxidants
, chemicals that
are known to provide certain health benefits to the
cardiovascular system

and
immune system
.
These chemicals are known to down
-
regulate the formation of
reactive oxygen species
, key
chemicals in
cardiovascular disease
.


20 MARKS:

4. Biochemist

Role

The
most common industry role is the development of biochemical products and processes.
Identifying substances' chemical and physical properties in biological systems is of great
importance, and can be carried out by doing various types of analysis. Biochemist
s must also
prepare technical reports after collecting, analyzing and summarizing the information and trends
found.

In biochemistry, researchers often break down complicated biological systems into their
component parts. They study the effects of foods, dr
ugs, allergens and other substances on living
tissues; they research molecular biology, the study of life at the molecular level and the study of
genes and gene expression; and they study chemical reactions in metabolism, growth,
reproduction, and heredity
, and apply techniques drawn from biotechnology and genetic
engineering to help them in their research. About 75% work in either basic or applied research;
those in applied research take basic research and employ it for the benefit of medicine,
agriculture
, veterinary science, environmental science, and manufacturing. Each of these fields
allows specialization; for example, clinical biochemists can work in hospital laboratories to
understand and treat diseases, and industrial biochemists can be involved in
analytical research
work, such as checking the purity of food and beverages.

Training

A degree in biochemistry or a related science such as
chemistry

is the minimum requirement for
any work in this field. This is sufficient for a position as a technical assistant in industry or in
academic settings. A Ph.D. (or equivalent) is generally required to pursue or direct independent
research. To advance furth
er in commercial environments, one may need to acquire skills in
management
.

Biochemistry requires an understanding of
organic

and
inorganic chemistry
. All types of
chemistry are required, with emphasis on biochemistry, organic chemistry and
physical
chemistry
. Basic classes in
biology
, including
microbiology
,
molecular biology
,
molecular
genetics
,
cell biology
, and
genomics
, are focused on. Some instruction in experimental
techniques and quantification is also part of most
curricula.

Employment

Biochemists are typically employed in the
life sciences
, where they work in the
pharmaceutical

or
biotechnology

industry in a research role. They are also employed in academic institutes,
where in addition to pursuing their research they may also be invo
lved with teaching
undergraduates, training graduate students, and collaborating with post
-
doctoral fellows.

Because of a biochemists' background in both biology and chemistry, they may also be employed
in the medical, industrial, governmental, and environ
mental fields. The field of medicine
includes
nutrition
,
genetics
,
biophysics
, and
pharmacology
; industry includes beverage and food
technology,
toxicolog
y
, and
vaccine

production; while the governmental and environmental
fields includes
forensic science
,
wildlife management
,
marine biology
, and
viticulture
.

5. Chemistry

Chemistry
, a branch of
physical science
, is the study of the composition, properties and
behavior of
matter
.
[1]
[2]

Chemistry is concerned wi
th atoms and their interactions with other
atoms, and particularly with the properties of
chemical bonds
. Chemistry is also concerned with
the interactions between atoms (or grou
ps of atoms) and various forms of energy (e.g.
photochemical reactions, changes in phases of matter, separation of mixtures, properties of
polymers, etc.).

Chemistry is sometimes called "
the central science
" because it connects physics with other
natural sciences

such as
ge
ology

and
biology
.
[3]
[4]

Chemistry is a branch

of
physical science

but
distinct from p
hysics
.
[5]

The etymology of the word chemistry has been much disputed.
[6]

The genesis of chemistry can
be traced

to certain practices, known as
alchemy
, which had been practiced for several
millennia

in various parts of the world, particularly the Middle East.
[7

Etymology

The word
chemistry

comes from the word
alchemy
, an earlier set of practices that encompassed
elements of chemi
stry, metallurgy, philosophy, astrology, astronomy, mysticism and medicine; it
is commonly thought of as the quest to turn lead or another common starting material into
gold.
[8]

The wo
rd
alchemy

in turn is derived from the
Arabic

word al
-
kīmīā (الكيمياء). The
Arabic term is borrowed from the Greek χημία or χημεία.
[9]
[10]

This may have
Egyptian

origins.
Many believe that al
-
kīmīā is derived from χημία,
which is in turn derived from the word
Chemi

or
Kimi
, which is the ancient name of
Egypt

in
Egyptian
.
[9]

Alternately, al
-
kīmīā may be derived
from χημεία, meaning "cast together".
[11]

An alchemist was called a
'chemist' in popular speech, and later the suffix "
-
ry" was added to this
to describe the art of the chemist as "chemistry".

Ancient Egyptians

pioneered the art of synthetic "wet
" chemistry up to 4,000 years ago.
[19]

By
1000 BC ancient civilizations were using technologies that formed the basis of the various
branches of chemistry such as; extracting metal fr
om their ores, making pottery and glazes,
fermenting beer and wine, making pigments for cosmetics and painting, extracting chemicals
from plants for medicine and perfume, making cheese, dying cloth,
tanning

leather,
rendering fat
into soap
, making glass, and making
alloys

like bronze.

Elements

An elemen
t is the smallest physical unit of an atom that retains distinctly different properties
.

An
element
is made up of one kind of atom. Most elements are solid and most are metals. So far, 113
elements have been discovered. Examples: oxygen, nitrogen, and lea
d. We don’t eat elements though
ele
mental sulfur is sometimes used in the garden or a winery. We breathe in elemental oxygen and
nitrogen.

Elemental oxygen is made up of two atoms of oxygen; this is also molecular oxygen. All this
nomenclature is confusi
ng yet its understand
ing will help you grasp a useful overview of the
chemistry of food and metabolism.

Each element is represented by a:



Chemical symbol



Atomic number



Atomic mass

What chemical symbols do you already know? Hydrogen? Carbon? Chlorine?

The number of electrons equals the number of protons in an atom; however, since an electron is so
small it’s not considered in the mass of an atom. Basically, the electrons are the particles in an
element that move and determine the chemical properties.

Ru
ssian scientist Dmitri Mendeleev discovered an order to the elements that he called families which
share similar properties. He put these families into a grid,
The Periodic Table of Elements.
Each
column of elements share some common properties. The elemen
ts that the human body can use are
those with lower molecular weights, basically those on the first four rows of the Periodic Table.
Remember the only difference between each of the elements is the number of protons, electrons and
neutrons, which are invis
ible subatomic particles.

6. Nutritional Biochemistry

Nutritional biochemistry is one of the academic foundations that make up nutritional sciences, a
discipline that encompasses the knowledge of
nutrients

and other food components with
emphasis on their range of function and influence on mammalian physiology, health, and
behavior. Nutritional biochemistry is a subdiscipline that is made up of the core knowledge,
concepts, and methodology related t
o the chemical properties of nutrients and other dietary
constituents and to their biochemical,
metabolic
, physiological, and epigenetic functions. A
primary focus of research in nutritional
biochemistry

is the scientific establishment of optimal
dietary intakes (Dietary Reference Intakes or DRIs) for every
nutrient

and food component
througho
ut the life cycle (Thomas and Earl, 1994; Standing Committee, 1998).

Nutritional biochemistry is an integrative science whose foundation is derived from knowledge
of other biological, chemical, and physical sciences, but it is distinguished in its applicat
ion of
this knowledge to understanding the interactive relationships among diet, health, and disease
susceptibility. For example, nutritional bio
-
chemistry is rooted in analytical methodology that
permits the purification of individual nutrients and the de
termination of their structures, as well
as in classical biochemical approaches that identify metabolic pathways and
elucidate

the role of
dietary components in regulating
metabolism

and gene expression. Additionally, human genetic
studies of inherited
inborn

errors of metabolism, such as
phenylketonuria
, have contributed to
core nutritional biochemical knowledge by revealing important interrelationships among
nutrition, metabolism, and
genotype

and their interactions during normal and

abnormal human
development.

Knowledge generated from nutritional biochemistry research forms the foundation upon which
nutrition
-
based public health interventions are designed and implemented. Many common
diseases and disabilities afflicting human populat
ions in both developing and developed
countries result from general
malnutrition
, deficiencies of specific nutrients, or overnutrition.
Inadequate diets or poor dietary habits are associated with in
creased risk for
morbidity

and
mortality, including birth defects, diabetes,
cardiovascular disease
,
obesity
, and certain cancers.
Specific nutrients, food components, or metabolites, singularly or in combination, can contribute
to risk for disease or, alternatively, can be protective by preventing disease. Furthermore,
associations a
mong dietary components and diseases are strongly influenced by subtle genetic
variation, such as single
nucleotide

polymorphisms, which are prevalent in all human
populations. Research
-
based diet the
rapies and strategies to decrease the incidence of nutrition
-
related diseases have a successful history of improving public health and individual quality of
life. Such strategies include (1) the fortification of grain products with
folic acid

to decrease the
incidence of common birth defects (
spina bifida
), (2) the iodinization of table salt to prevent
cretinism
, a developmental disorder associated with severe
neurological

and cognitive deficits in
children, and (3) the promotion of diets low in
cholesterol

to prevent and to manage
cardiovascular disease. These nutrition
-
based interventions have impacted the quality of life for
individuals, and the monetary effects associated with the
amelioration

of these disorders have
significantly benefited health care systems and national economies.

Current research and discovery in nutritional biochemistry is focused broadly in several areas,

including nutritional genomics and metabolomics. Nutritional genomics is the study of genome

nutrient interactions and includes (1) the role of nutrients and dietary components in regulating
genome structure, expression, and stability, and (2) the role of

genetic variation on individual
nutrient requirements. Nutritional metabolomics is the study of metabolic pathways and
networks and includes (1) the regulation of metabolic pathways and networks, by nutrients and
other food components, and (2) the establi
shment of analytical methods that "profile" human
serum

and
urinary

metabolites to assess nutritional imbalances and disease risk. It is anticipated
tha
t knowledge derived from these new approaches will enable nutrient requirements to be
tailored to an individual's genetic profile for optimal health throughout the life cycle. In addition,
information obtained from these new technologies will inform effort
s (1) to improve or to
enhance the food supply through the targeted introduction of traditional or novel foods, (2) to
fortify food chemically with specific nutrients, or (3) to enhance crops genetically for higher
nutrient content or quality.

Nutritional
sciences academic training programs with a strong emphasis in nutritional
biochemistry reside in medical colleges (e.g., Columbia University), schools of public health
(e.g., Harvard University), and land grant universities (e.g., Cornell University). Nutr
itional
sciences training programs can be independent units, jointly administered or affiliated with
programs of
toxicology
, biochemistry, animal sciences, food sciences, and various medical
programs.

Academic faculty in nutritional biochemistry can be expert in many disciplines,
including chemistry, biochemistry, genetics, and physiology. Therefore, individual nutritional
sciences programs with distinct nutritional biochemistry concentrations are high
ly unique.
Nutritional biochemists establish careers in teaching and research within universities,
governmental and regulatory agencies, and the food, pharmaceutical, or
biotechnology

industries. N
utritional biochemists may also work in fields related to public policy, health care,
or product development and marketing in the food industry.

Core Knowledge That Defines Nutritional Biochemistry



Structure and function of nutrients and other dietary cons
tituents



Chemical structure and metabolic functions of essential and
nonessential

nutrients



Physiological and biochemical basis for nutrient requirements



Motifs of absorption and transport of nutri
ents



Integration, coordination, and regulation of macro
-
and
micronutrient

metabolism



Regulation of nutrient metabolism and nutritional needs by
hormones

and growth factors



Interaction of nutrients with the genome; nutrient control of gene expression; DNA
stability



Dietary bioactive components (functional foods)

nontraditional roles of nutrients



Food, diets, and supplements



Food sources of nutrie
nts and factors affecting nutrient bioavailability



Effect of food processing and handling on nutrient content and bioavailability



Nutritional toxicology

upper limits of intake; nutrient

nutrient and drug

nutrient
interactions



Dietary Reference Intakes
(DRIs); Food Guide Pyramid



Nutrient supplements

risks/benefits, life stage, bioavailability



Molecular markers of nutrient intake

gene arrays and analytical chips



Nutrition and disease



Impact of disease and genetics on nutrient function and requirements



Gen
etic basis of inherited metabolic disease


7. Fundamentals of Nutrition/Nutritional Biochemistry

Nutrition is the nourishment of an organism to support its functions, with substances called
nutrients. In humans, nutrition more specifically refers to the co
nsumption, absorption,
utilization and excretion of essential chemical compounds found in foods and drinks that are
required by the body to produce energy as well as to assist the body to grow and develop.
Nutrients also help the body prevent or fight dise
ases more effectively. There are six major
classes of nutrients which include carbohydrates, fats, proteins, vitamins, minerals and water.
Other substances have been identified that play an important role in human health such as
phytochemicals, but are not

yet considered being essential. Nutrients cannot be created by the
body and thus must be obtained through diet. Diet, in turn, refers to the total consumption of
food by an organism and is sometimes used interchangeably with nutrition, although the two
te
rms have different meanings.

Nutritional science is the study of nutrients, their function and how they are involved in health
and disease. The goal is to ensure specific nutritional guidelines suitable for different groups of
people depending on their age
, sex, activity level and special groups such as in pregnancy or
disease. It is a relatively new discipline and began to evolve the last 100 years, even though the
importance of diet to maintain health was recognised a lot earlier. It is an applied subject

that
draws information from many other biological areas particularly biochemistry, therefore a good
understanding of biochemistry is required to fully understand nutrition. Nutritional scientists
employ many of the techniques used in biochemistry, althoug
h nutritionists are more health
oriented and concerned particularly with nutrients. In fact, the wealth of knowledge of nutrition
is greatly attributed to biochemists.

In the following chapters we discuss the biochemistry of nutrients and how they are meta
bolised
in the body.

1.
Energy Metabolism

2.
Carbohydrates

3.
Lipids

4.
Proteins

5.
Vitamins

6.
Minerals

7.
Other substances

Hypothetical types of biochemistry

Hypothetical types of biochemistry

are forms of
biochemistry

speculated to be scientifically viable but
not proven to exist at this time. While the kinds of
living beings we know on Earth

commonly use
carbon

for basic structural and
metabolic

functions,
water

as a
solvent

and
DNA

or
RNA

to define and control
their form, it may be possible that undiscovered life
-
forms could exist that differ radically in their basic
structures and biochemistry from that known to science.

Silicon biochemistry

The most commonly proposed basis for an alte
rnative biochemical system is the silicon atom,
since silicon has many
chemical properties

similar to carbon and is in the same
periodic table
group
, the
carbon group
. Like carbon, silicon can create molecules that are sufficiently large to
carry biological
information.
[17]

However, silicon has several drawbacks as a carbon alternative. Silicon, unlike carbon, lacks the
ability to form chemical bonds with diverse types of atoms necessary for the chemical versatility
required for
metabolism
. Elements creating organic functional groups with carbon include
hydrogen, oxygen, nitrogen, phosphorus, sulfur, and metals such as iron, magnesium, and zinc.
Silicon, on the other hand, interacts with very few other typ
es of atoms.
[17]

Moreover, where it
does interact with other atoms, silicon creates molecules that have been described as
"monotonous compared with the combinatorial universe of organic macromolecules".
[17]

This is
because silicon atoms are much bigger, having a larger
mass

and
atomic r
adius
, and so have
difficulty forming double bonds (the double bonded carbon is part of the
carbonyl

group, a
fundamental motif of bio
-
organic chemistry).

Silanes
, which are
chemical compounds

of
hydrogen

and silicon that ar
e analogous to the
alkane

hydrocarbons
, are highly reactive with
water
, and long
-
chain silanes spontaneously decompose.
Molecules incorporating
polymers

of alternating silicon and
oxygen

atoms instead of direct
bonds between silicon, known collectively as
silicones
, are much more stable. It has been
suggested that silicone
-
based chemicals wou
ld be more stable than equivalent hydrocarbons in a
sulfuric
-
acid
-
rich environment, as is found in some extraterrestrial locations.
[18]

Complex

long
-
chain silicone molecules are still less stable than their carbon counterparts, though.

Another obstacle is that
silicon dioxide

(a common ingredient of many sands), the

analog of
carbon dioxide
, is a non
-
soluble

solid at the temperature range where water is liquid, making it
difficult for silicon to be introduced into water
-
based biochemical systems even if the necessary
range of biochemical molecules could be constructed out of it. Another problem with silicon
d
ioxide is that it would be the product of aerobic respiration. If a silicon
-
based life form were to
breathe using oxygen, as life on Earth does, it would possibly produce silicon dioxide as a
by
-
product

of this, assuming that the only difference between the two types of life is silicon in place
of carbon. This implies that the exhaled product, silicon dioxide, would be a solid, thus filling the
respiratory organs of the organism with sa
nd. This however would be solved if the organism
lives in temperatures of several hundred to thousand degrees, where the silicon dioxide becomes
a liquid. Oxygen
-
breathing silicon life, if it exists, is therefore most likely to exist in
environments with v
ery high temperatures or pressure.