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Exploring DNA: Structure, Functions, and Replication

Discover the intricate structure and essential functions of DNA, the genetic powerhouse found in cells. Learn about nucleotides, base pairs, and the fascinating process of DNA replication. Explore the contributions of key scientists and unravel the mysteries of DNA in this comprehensive guide.

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Exploring DNA: Structure, Functions, and Replication

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  1. DNA Structure

  2. DNA… WHAT IS IT!?!?! • DNA stands for DEOXYRIBONUCLEIC ACID • DNA holds genetic information in cells • DNA is a nucleic acid polymer. • The monomer of a nucleic acid is a nucleotide. • Nucleotides have 3 components: • Sugar • Phosphate • Nitrogen base

  3. Complimentary base pairing Adenine pairs with Thymine Guanine pairs with Cytosine The size of the purine weakly hydrogen bonded to a pyrimidine creates a DNA strand that is equal in width

  4. Complimentary base pairing continued • The opposite arrangement of the nucleotides gives the DNA strands direction and allows for the antiparallel orientation.

  5. Complimentary base pairing continued • The covalent bond between the sugar and phosphate gives the DNA two STRONG backbones  Get out your nucleotide…number the carbons on your nucleotide now

  6. ANOTHER NUCLEIC ACID • RNA • RNA stands for Ribonucleic Acid • It acts as a messenger between DNA and the cytoplasmic tools that make proteins • RNA is different from DNA … • RNA contains the sugar RIBOSE • RNA is single stranded • RNA contains the nitrogen base Uracil and does NOT contain Thymine

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  8. REVIEW Describe the contributions of the following scientists in the discovery of genetic material. Your description may be in sentence, table, picture, poetry, and/or cartoon format. • Frederick Griffith • Oswald Avery • Alfred Hershey and Martha Chase • Erwin Chargaff • Linus Pauling, Rosalind Franklin and Maurice Wilkins • James Watson and Francis Crick

  9. DNA Replication

  10. Replication • What is it? Why does it happen? • The DNA molecule copies itself for the new cells • When does it happen? • During the cell cycle(interphase/synthesis) just before mitosis and/or meiosis.

  11. Replicate! • What is the complimentary strand for this segment of DNA? • G C T A C T G G A C A T T A • C G A T G A C C T G T A A T • END RESULT  Two identical DNA molecules!

  12. Results? • Replication simple • http://www.youtube.com/watch?v=hfZ8o9D1tus • Project example of replication • http://www.youtube.com/watch?v=Bju4C5GxeQs • Replication with leading and lagging strand • http://www.youtube.com/watch?v=vNXFk_d6y80

  13. Semi-conservative replication • Matthew Meselson and Franklin Stahl studied DNA replication using E. coli and isotopes of Nitrogen. • They developed a model of DNA replication that showed a semi-conservative process. • Original splits • Half is conserved & half is new in each new strand

  14. How does it happen? • The enzyme helicase attaches at the origin of replication and breaks the hydrogen bonds and unzips the 2 DNA strands in both directions. • Complimentary bases (from the cytoplasm/nucleus) attach to both unzipped strands. • The enzyme DNA polymerase bonds the sugar-phosphate ladder sides and the nucleotide ladder rungs to the 3’ end of the DNA molecule.

  15. How does it happen? Continued… • Two strands of DNA are replicated in different directions • Strand one (the leading strand 5’  3’) can replicate continuously

  16. How does it happen? Continued… • Strand two (the lagging strand 3’  5’) is replicated in pieces (discontinuously). The Okazaki fragments are connected by enzyme DNA ligase. • Errors and damage in DNA are fixed by DNA polymerases and DNA ligase.

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