briefly about dna structure and nutrigenomics.

1. DNA: Watson & Crick perspective
Deoxyribonucleic acid (DNA) is a molecule that carries the genetic instructions used in the growth,
development, functioning and reproduction of all known living organisms and many viruses. DNA and
RNA are nucleicacids;alongside proteins,lipidsandcomplexcarbohydrates (polysaccharides), they are
one of the fourmajor typesof macromoleculesthatare essential for all known forms of life. Most DNA
molecules consist of two biopolymer strands coiled around each other to form a double helix. DNA
stores biological information. This information is replicated as and when the two strands separate. A
large part of DNA (more than98% for humans) isnon-coding,meaning that these sections do not serve
as patterns for protein sequences.
Double Helix structure of DNA
• Chargaff's realization that A = T and C = G, combined with some crucially important X-ray
crystallographyworkbyEnglishresearchersRosalindFranklinand Maurice Wilkins, contributed
to Watson and Crick's derivation of the three-dimensional, double-helical model for the
structure of DNA. DNA isa double-strandedhelix,withthe two strands connected by hydrogen
bonds.A basesare alwayspairedwith Ts, and Cs are always paired with Gs, which is consistent
with and accounts for Chargaff's rule.
• Most DNA double helicesare right-handed;thatis,if youwere to hold your right hand out, with
your thumb pointed up and your fingers curled around your thumb, your thumb would
representthe axisof the helix andyourfingerswouldrepresentthe sugar-phosphate backbone.
Only one type of DNA, called Z-DNA, is left-handed.
• The DNA double helix is anti-parallel, which means that the 5' end of one strand is paired with
the 3' end of its complementary strand (and vice versa). As shown in Figure 4, nucleotides are
linkedtoeachotherby theirphosphate groups,whichbindthe 3'end of one sugar to the 5' end
of the next sugar.
Nutrigenomics
Nutrigenomics is a branch of nutritional genomics and is the study of the effects of foods and food
constituentson gene expression.Thismeansthatnutrigenomicsisresearch focusing on identifying and
understanding molecular-level interaction between nutrients and other dietary bioactives with
the genome.The interactionbetweengeneticanddietary influencescanresultina higherrisk of disease
incertainindividualsandpopulations.Currently,diet-gene association studiesare revealingevidence on
which to base gene-specific dietary intervention trials to confirm results.
By determiningthe mechanismof the effects of nutrients or the effects of a nutritional regime,
nutrigenomicstriestodefine the causalityorrelationshipbetweenthese specific nutrients and specific

2. nutrient regimes (diets) on human health. Nutrigenomics has been associated with the idea of
personalizednutritionbasedongenotype.While there ishope thatnutrigenomicswillultimatelyenable
such personalised dietary advice, it is a science still in its infancy and its contribution to public
health over the next decade is thought to be major. Whilst nutrigenomics is aimed at developing an
understandingof howthe whole bodyrespondstoafoodviasystemsbiology,researchintothe effect of
a single gene/single food compound relationships is known as nutrigenetics.
Aging of cells occur because of the accumulation of excess free radicals formed due to the lack
of propernutritiontothe cellsandexternal factorslike UV rays,pollution,stress,food,etc.DNA analysis
is instrumental in identifying the right concoction of nutrients needed to eliminate the excess free
radicals present in the cell. Obesity is one of the most widely studied topics in nutrigenomics. Due to
genetic variations among individuals, each person could respond to diet differently. By exploring the
interaction between dietary pattern and genetic factors, nutrigenomics aim to suggest prevention
measures and/ or treatment to obesity via personal nutrition.
To put nutrigenomics into practice, genetic testing is required as the test results act as the
reference for diagnosis. As the subject is recently commercialized by companies which sell direct to
customer (DTC) genetic tests, as well as being applied by related professionals (such as dietic
practitioners), there have been increased awareness in the use of this information. These concerns
include but are not limited to the lack of analytical and clinical validity of genetic tests, emotional
distress of consumers, and other social concerns.
One of the major concerns regarding genetic tests would be privacy issue. There are concerns on who
has the right to have access to test results. Abuse of these tests could result in discrimination. For
example,geneticinformationmightbe usedbyinsurance companiestoriskrate theirclients.One of the
possible ethical concernsarise wouldbe private companiesproviding unverified information regarding
testresults. Interpretationsongenetictestresultsneedstobe handledverycarefully Misleadingand/or
inaccurate information may as well undermine customers' ability to make informed decisions.
Misinterpretation could possibly mislead patients and hence false medical claims are made.
Refrences
1. Watson, J. D., & Crick, F. H. C. A structure for deoxyribose nucleic acid. Nature 171, 737–738
(1953).
2. In Dube L, Bechara A, Dagher A, Drewnowski A, LeBel J, James P, Yada RY & Laflamme-Sanders
M-C. Obesity Prevention: the role of society and brain on individual behavior. pp. 149-160.
3. Müller M, Kersten S. (2003). Nutrigenomics: goals and strategies. Nature Reviews Genetics. 4(4):
315-322.
4. Castle,David;Ries,NolaM. (2007-09-01). "Ethical, legal and social issues in nutrigenomics: The
challenges of regulating service delivery and building health professional capacity". Mutation
Research/Fundamental and Molecular Mechanisms of Mutagenesis. Nutrigenomics. 622 (1–2):
138–143.
Presented By :- NISHA (20863)
ANIL KUMAR (20835)
BALWANT SINGH (20836)