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Unraveling the DNA Structure: The Molecule of Life and Replication Process

Explore the intricate DNA structure shared by all organisms, its crucial role as the molecule of life containing genetic information for cell functions, growth, and division. Delve into the discovery of the double helix shape by Watson & Crick, the composition of nucleotides, and the base-pairing rules of Adenine-Thymine and Cytosine-Guanine. Learn how DNA replication works through processes involving DNA helicase, polymerase, and the formation of replication bubbles with leading and lagging strands. Understand the significance of semi-conservative replication in producing two complete DNA copies.

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Unraveling the DNA Structure: The Molecule of Life and Replication Process

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  1. KEY CONCEPT DNA structure is the same in all organisms.

  2. DNA is the molecule of Life • Deoxyribonucleic Acid • Containsgenetic information for cell functions, growth, and division • Shape – Double Helix • Watson & Crick – Discovered the shape of DNA

  3. phosphate group nitrogen-containing base deoxyribose (sugar) • DNA is made up of a long chain of nucleotides. • Each nucleotide has three parts. • a phosphate group • a deoxyribose sugar • a nitrogen-containing base

  4. DNA is composed of four types of nucleotides. • -Adenine -Thymine • -Cytosine -Guanine

  5. Watson and Crick determined the three-dimensional structure of DNA by building models. • DNA is a double helix that is made up of a sugar-phosphate backbone on the outside with bases on the inside.

  6. G C A T Nucleotides always pair in the same way. • The base-pairing rules show how nucleotides always pair up in DNA. • A pairs with T • C pairs with G

  7. covalent bond hydrogen bond • The backbone is connected by covalent bonds. • The bases are connected by hydrogen bonds.

  8. History of Replication • Watson & Crick – realized that complementary base pairing provided a way for DNA to copy itself - base pairing could allow a new strand to be built on an old strand

  9. DNA Replication – • Replication = DNA making copies of itself • DNA must be copied before a cell can divide • Each new cell will have a complete set of DNA

  10. DNA Replication: Process • Replication begins when the enzyme DNA helicaseopens the DNA forming replication bubbles

  11. DNA Replication- The Big Picture Each Bubble has 2 Forks – each fork has a leading and lagging strand

  12. DNA Replication – DNA Polymerase • The enzyme DNA polymerase brings new nucleotides to the replication fork - it pairs them according to base pairing rules A pairs with T C pairs with G

  13. DNA Replication • The process continues until 2 complete copies of the DNA are produced • Each copy of the DNA contains one strand of DNA from the original DNA molecule and one new strand that was produced by replication • Known as semi-conservativereplication

  14. DNA Replication

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