The document summarizes key aspects of DNA structure and function. It describes the scientists involved in discovering DNA, including Watson, Crick, Wilkins and Franklin. It explains that DNA is located in the nucleus of cells and is made up of nucleotides containing a sugar, phosphate, and nitrogenous base. The bases adenine and thymine pair together, as do cytosine and guanine. DNA replicates through the bases separating and new strands forming complementary pairs. DNA fingerprinting can be used to identify individuals and determine genetic relationships.

1. LIFE SCIENCES
PRESENTATION: THE
DNA
REPURPOSING PRESENTATION.

2. THE HISTORY OF DNA
• The scientists involved in the discovery of the DNA by ( The university of
Mumbai, 2014)
• on the image are only three scientists
that had
• a contribution towards DNA
phenomenon.
• others include James Watson, Francis
• Crick, Maurice Wilkins and Rosalin
• franklin.

3. SOME OF THE CONTRIBUTIONS BY THE SCIENTISTS.
• Phoebus Levene is the one that discovered the three components that
make up the DNA which will be mentioned later in the presentation.
• James Watson and Francis Crick discovered that the DNA can “unzip” and
make new copies of itself otherwise called as DNA replication (university
of Mumbai, 2014), which will also be elaborated on at a later stage of the
presentation.
• Rosalind Franklin used the method of an x-ray crystallography to establish
and assist with the visualization of the structure of a DNA which is a
double helix. ( Mendoza, 2012)

4. WHERE IS THE DNA IN A CELL LOCATED ?

5. THE LOCUS: THE PLACE WHERE GENES ARE
FOUND IN CHROMOSOMES.
• 1. The chromatin is a substance which is found in a chromosome and it consists
of both protein and DNA , it is found in the nucleus of eukaryotic cells.
• 2. The main proteins in a chromatin are histones. (Tenderness, 2017)
• 3. The DNA (deoxyribonucleic acid) can be defined as a molecule that is located
in the nucleus of a cell and is made up of two strands which are polynucleotide
that form a double helix and it works to transmit genetic information. See image
below.

6. THE STRUCTURE OF A NUCLEOTIDE
• It comprises of three elements.
• 1. A pentose sugar (deoxyribose in DNA and ribose in RNA). It is a five carbon
sugar.
• 2. A phosphate group which links the sugar on one nucleotide to the phosphate
of another nucleotide , creating a polynucleotide.
• 3. A nitrogenous base , which is found in both DNA and RNA. (Tenderness, 2017)
DNA RNA
adenine adenine
thymine thymine
cytosine cytosine
guanine uracil

7. NITROGENOUS BASES
• Cytosine pairs with guanine while adenine pairs with thymine.
• These bonds happen through hydrogen bond which is a weak bond and is easily
broken
• They are usually broken through the process of DNA replication and the process of
protein synthesis.
• DNA replication can be described as when the DNA makes copies of itself (Khoza,
2012).
• Protein synthesis however is the formation of proteins within ribosomes which can be
found in and out of cells.
• There are two enzymes responsible for the breaking down of hydrogen bonds in DNA,
namely HELICASE and RNA POLYMERASE.

8. DNA FINGERPRINTING.
• Every human being has a different DNA sequence except for identical twins (
conceived from the same egg cell and sperm cell).
• if twins are not identical, they are referred to as fraternal twins ( developed from
different egg cells and sperm cells) (Khoza, 2012).

9. WHAT ARE THE USES OF DNA FINGERPRINTING?
 Paternity of a child – Fingerprinting is important when there is uncertainty of who the father
of the child is, the DNA can tell who is closest to paternity to the child by the DNA . (Khoza,
2012)
 Mapping genography- this is where the pattern of migration can be observed.
 Individual/ Personal identification- DNA fingerprinting is one of the best if not the best
method of identifying a person and it is the most accurate method. This can be important for
things like crime investigations where someone’s DNA can be put at a scene of a certain crime
or for forensics when it comes to identifying a person’s body remains.
 Identifying genetic disorders- some diseases can be genetic and DNA fingerprinting is good
way of recognizing whether a disease may be carried by someone’s offspring or not. (Khoza,
2012)

10. THE PROCESS OF REPLICATION OF THE DNA
• In the previous slides, we touched on the fact that DNA is able to replicate itself,
so how might this process happen?
• Whenever cell division occurs, the DNA should
• be copied so as to make sure that every cell
• has the exact DNA as the parent cell as
• mentioned by ( cross, 2010).

11. DNA REPLICATION CONT…
• The two strands that make up the double helix shape of the DNA separate due to
the hydrogen bonds between them breaking as a results of enzymes.
• These two single strands are able to take free nucleotides from the nucleoplasm
and form new strands that are double.
• But adenine can only pair up with thymine and guanine can only pair up with
cytosine therefore these new strands will be identical to each other and the initial
or original strands.

12. ILLUSTRATIONBY (CROSS, 2010)

13. REFERENCE LIST
• Cross., D. 2012. DNA – the molecule of life. Available at :
https://www.slideshare.net/desmondcross/dna-for-grade-12?qid=2169b021-6ab7-4004-9285-
24f52936896a&v=&b=&from_search=1
• Mendoza., E.G. 2012. DNA Structure and Function.
https://www.slideshare.net/elishagracediamsay/dna-structure-and-function-diamsay-mendoza
• Khoza., T.N. 2012. DNA FINGERPRINTING. Available at:
https://www.slideshare.net/thobilentombizodwakhoza/dna-fingerprinting-14883809?qid=2169b021-
6ab7-4004-9285-24f52936896a&v=&b=&from_search=3
• Tenderness., S.2017. DNA GRADE 12. available at :
https://www.slideshare.net/SiyabongaTenderness/dna-slides-grade-12-life-sciences?qid=2169b021-
6ab7-4004-9285-24f52936896a&v=&b=&from_search=2
• The university of Mumbai. 2014. DNA. Available at:
https://www.slideshare.net/search/slideshow?searchfrom=header&q=the+university+of+mumbai+life
+science&ud=&ft=&lang=&sort=