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DNA forms and Structures 0723bh-e-zoo-20.pptx
- 1. DNA forms andstructures PRESENTATION BY: MUHAMMAD AWAIS TARIQ 0723-BH-E-ZOO-20
- 2. What is DNA? DNA is a group of molecules that is responsible for carrying and transmitting the hereditary materials or the genetic instructions from parents to offsprings. DNA is known as Deoxyribonucleic acid.It is an organic compound that has a unique molecular structure. It is found in all prokaryotic and eukaryotic cells. Nuclear DNA is the DNA contained within the nucleus of every cells in eukaryotic organisms. It codes for the majority of organisms genome.
- 3. The DNApresent in the mitochondria of the cell is termed as mitochondrial DNA.It is inherited from mother to the child. In humans,there are approximately 16,000 base pairs of mitochondrial DNA. Similarly plastids have their own DNA and they play an essential role in photosynthesis.
- 4. Discovery of DNA DNA was first recognized and identified by the Swiss biologist Johanes Friedrich Meischer in 1869 during his research on white blood cells. The double helical structure of a DNA molecule was later discovered through the experimental data by James Watson and Francis Crick. It was proved that DNA is responsible for storing genetic information in living organisms.
- 5. DNA Diagram DNAcomprises a sugar phosphate backbone and the nucleotide bases. The bases includes guanine ,cytosine, adenine and thymine.
- 6. Chargaff’s Rule ErwinChargaff ,a biochemist ,discovered that the number of nitrogenous bases in the DNA was present in equal quantities. The amount of A is equal to T ,whereas the amount of C is equal to G. A=T;C=G
- 7. DNA Structure TheDNA structure can be thought of as a twisted ladder.This structure is described as a double helix . It is a nucleic acid and all nucleic acids are made up of Nucleotide and each nucleotide is composed of three different components such as sugar ,phosphate groups and nitrogenous bases. The sugar and phosphate group links the Nucleotides together to form each strand of DNA.
- 8. There are4 Nitrogenous base pairs together in the following way:A with T ,and C with G. These base pairs are essential for the DNA’s double helical structure ,which resembles a twisted ladder. The order of the nitrogenous bases determine the genetic code or the DNA’s instructions.
- 10. Among thethree components of DNA structure, sugar is the one which forms the backbone of the DNA molecule.It is also called deoxyribose.
- 11. The twostrands of DNA run in opposite directions. These strands are held together by the hydrogen band that is present between the two complementary bases. The strands are helical twisted ,where each strand forms a right handed coil,and then Nucleotides makes up a single turn. The pitch of each helix is 3.4 nm.Hence ,the distance between two consecutive base pairs is 0.34nm.
- 12. DNA Types Thereare three different DNA types which are as follows: A-DNA B-DNA Z-DNA
- 13. A DNA Itis a right handed double helix similar to the B-DNA form. Dehydrated DNA takes an A form that protects the DNA during extreme conditions such as dedication. Protein binding also removes the solvent from DNA and DNA takes A form.
- 14. B-DNA This isthe most common DNA conformation and it is right handed helix. The majority of DNA has a B type conformation under normal Physiology conditions.
- 15. Z-DNA Z-DNA isa left handed DNA where the double helix winds to the left in zig zag pattern. It was discovered by Andres Wang and Alexander Rich. It is found ahead of the start site of a gene and hence, is believed to play some role in gene regulation.
- 16. DNA Function DNAis the genetic material which carries all the hereditary information. Apart from storing genetic information, DNA is involved in: Replication process:Transferring the genetic information from one cell to its daughter and from one generation to next and equal distribution of DNA during the cell division. Mutations. Transcription Cellular metabolism Gene therapy