DNA STRUCTURE AND FUNCTION

DNA is the chemical responsible for the transmission of genetic information from one generation to next.
STRUCTURE
[coverattach=1]There are four nitregenous bases in DNA Adenine, Guanine, Thymine and Cytosine.The structure of DNA was discovered by James Watson and Francis Crick in 1953.They discovered the DNA consists of two chains of nucleotides,
twisted around each other to form a double helix. The pairing
between adjacent bases in DNA follows containing rules.Adenine always pairs with Thymine and Guanine always pairs with Cytosine.Knowing the sequence of bases in one strand allows the composition of its partner to be pedicted with certainly.

REPLICATION

Every time when a cell divides, a new copy of all the DNA is made.This involves to process called replication.A of DNA replication was suggested by Watson and Crick, based on the complementary nature of the two strands and the base-pairing rules.DNA can form a copy of one strand.

DNA FINGERPRINTING

The chemical structure of everyone’s DNA is the same.The only difference between people is the order of the base pairs.There are millions of base pairs in each persons DNA that every person could be identified by the sequence of their base pairs.These patterns do not, however, give an individual “fingerprinting”, but they are able to determine whether two DNA samples are from the same person, related people, or non-related people.
Scientists are doing this process by this methods:
1. Isolating the DNA from the rest of the cellular material in the nucleus.This can be done either chemically or mechanically.
2. Cutting the DNA into several pieces of different sizes.
3. Sorting the DNA pieces by size.
4. Denaturing the DNA.
5. Blotting the DNA.
This “DNA fingerprinting” is used for this events.
1. Paternity and maternity.
2. Criminal Identification and Forensics.
3. Personal Identification.

I. Generating a high probability:
The probability of a DNA fingerprinting belonging to a specific person needs to be reasonable, high especially in criminal cases.
II. Problems with determinating probability:
a. Population genetics:
If DNA bases like each other.
b. Technical difficulties:
If there is not enough machine to do the research.
GLOSSARY
Hybridzation: To mix two different DNAs and form a mixed DNA.
Adenine: A nitrogen and carbon containing molecule in the form of nucleotides, such as the energy-rich molecule ATP and nucleic acids, such as DNA and RNA.,[coverattach=2]
Cytosine: A nitrogen and carbon form of a single ring that is a major component of nucleotides and the nucleic acids DNA and RNA.
Guanine: A nitrogen and carbon form of a single ring that is a major component of nucleotides and the nucleic acids DNA and RNA.
Thymine: A nitrogen and carbon form of a single ring that is a major component of nucleotides and the nucleic acid DNA.

PEOPLE
Francis Circk: English biologist Francis Crick is noted for his co-discovery of the structure of DNA.Crick started researching the properties of organic molecules in 1947.In 1953 he and James Watson discovered that the DNA molecule is shaped like double helix.For this research, Crick and Watson shared the 1962 Nobel Prize.
James Watson: American biologist James Watson and the British biologist Francis Circk found that “DNA is found in every living organism.” Watson has researched also added to our understanding of the behaviour of the genes that cause herediatory diseases.

[coverattach=3]Rosalind Franklin: British molecular biologist Rosalind Franklin played a major role in the structure of the DNA molecule.In 1951 she obtained the images of the DNA.Crick’s and Watson’s researches are based on Franclins’ data.

Barbara McClintock: The American biologist Barbara McClintock is famous for her reseach “How physical characteristics are passed from one generation to next.” Her other findings were genes, chromosomes and DNA in the nucleus.

Oswald Avery:Oswal Avery was a Canadian bacteriologist whose work during late 19th and early 20th demostrated that DNA carries heritable characteristics.Avery, refined the material used in this inoculation and after further experiments, conculuded DNA was responsible for the changes brought about in the bacteria.But other reseachers were disagreed with Oswald Avery.

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