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Introduction-to-DNA | Discovery | Chemical Structure
- 1. DNA The hereditary material By-Sana Shaikh
- 2. What is DNA ? 1. DNA also known as Deoxyribonucleic acid, 2. It is the blueprint of life. 3. It holds the genetic instructions for all living organisms. 4. DNA is a molecule that contains the genetic code, which determines an organism's traits. 5. It is located in the cell nucleus (where it is called nuclear DNA), 6. A small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
- 3. Discovery of DNA 1 1869: Friedrich Miescher Isolates Nuclein Swiss chemist Friedrich Miescher discovered a new substance in the nucleus of white blood cells, which he called "nuclein." This substance was later identified as DNA. 2 1944: Avery, MacLeod, and McCarty's Experiment Oswald Avery, Colin MacLeod, and Maclyn McCarty demonstrated that DNA is the genetic material responsible for inheritance. This was a major breakthrough in our understanding of DNA's role in life. 3 1953: Watson and Crick's Double Helix Model James Watson and Francis Crick, with help from Rosalind Franklin and Maurice Wilkins, determined the structure of DNA as a double helix. This discovery was a landmark achievement in science.
- 4. Chemical structure of DNA 1 Sugar-Phosphate Backbone DNA is made up of two long strands of nucleotides, linked together by a sugar-phosphate backbone. These strands are twisted around each other to form a double helix. The sugar-phosphate backbone gives DNA its structural integrity and flexibility. Thymidine Adenine Cytosine
- 5. 2 Nitrogenous Bases The nucleotides in DNA are made up of a sugar, a phosphate group, and a nitrogenous base. The four nitrogenous bases in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T).
- 6. 3 Complementary Base Pairing The nitrogenous bases on one strand of DNA pair with the nitrogenous bases on the other strand. Adenine always pairs with thymine with two hydrogen bonds, and guanine always pairs with cytosine with three hydrogen bonds. This base pairing is essential for DNA replication and the transmission of genetic information. 4 Double Helix The two strands of DNA are held together by hydrogen bonds between the nitrogenous bases. The two strands twist around each other to form a double helix, giving DNA its characteristic helical shape. A G C
- 7. Genetic information in DNA Genes DNA is organized into units called genes, which contain instructions for building proteins. These proteins perform a wide range of functions in the body, from building tissues and organs to regulating metabolism and immune responses. Codons The sequence of nitrogenous bases in DNA is read in groups of three called codons. Each codon codes for a specific amino acid, which is the building block of proteins. Genetic Code The genetic code is the set of rules that relates codons to amino acids. It is nearly universal, meaning that the same codons code for the same amino acids in all living organisms.
- 8. Mutations and genetic disorders Mutation Description Effect Point Mutation Change in a single base Can alter the amino acid sequence of a protein, leading to a change in its function Insertion Addition of one or more bases Can shift the reading frame, altering the amino acid sequence and protein function Deletion Removal of one or more bases Similar to insertion, can shift the reading frame, leading to a change in the amino acid sequence and protein function
- 9. Future of DNA research Gene Editing CRISPR-Cas9 is a powerful tool that allows scientists to precisely edit DNA sequences. This technology has the potential to cure genetic disorders, develop new treatments for diseases, and improve crop yields. Personalized Medicine DNA sequencing is being used to develop personalized medicine approaches, tailoring treatments to an individual's genetic makeup. This allows for more effective and targeted therapies, minimizing side effects and improving outcomes. Forensic Science DNA analysis has become a crucial tool in forensic science, used for identifying suspects, determining paternity, and resolving criminal cases. Evolutionary Biology DNA sequencing is revolutionizing our understanding of evolution. It allows us to study the genetic relationships between different species and trace the history of life on Earth.
- 10. DNA Replication Unwinding The double helix is unwound by an enzyme called helicase, which breaks the hydrogen bonds between the nitrogenous bases. Base Pairing Each strand of DNA serves as a template for the synthesis of a new complementary strand. An enzyme called DNA polymerase adds nucleotides to the new strand, following the rules of base pairing: A with T, and G with C. New Strands Two identical DNA molecules are formed, each containing one original strand and one new strand. This process ensures that each daughter cell receives a complete copy of the genetic information. Lagging strand