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DNA: The Molecule of Heredity

Learn about the structure and function of DNA, the molecule that holds the genetic information in cells. Discover how DNA is made up of nucleotides and how these nucleotides pair up to form the double helix structure. Explore the process of DNA replication and its importance in maintaining genetic integrity.

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DNA: The Molecule of Heredity

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  1. DNA: The Molecule of Heredity

  2. The Size of DNA... If the DNA of one cell is stretched out, it makes a 7 ft. long string There are about 5 trillion cells in the human body If you connected all the DNA together, it would be long enough that it would take light over 10 hours to travel its length (ruptured bacteria)

  3. DNA • Codes for your genes • Located inside the nucleus in the form of chromosomes

  4. Nucleotides • DNA is made up of repeating units called NUCLEOTIDES • Nucleotides have 3 parts: • Simple sugar • Phosphate • Nitrogenous base

  5. Nucleotides A) Simple sugar = deoxyribose (the sugar gives it its name deoxyribonucleic acid) B) phosphate group C) 1 nitrogenous base • Adenine • Guanine • Cytosine • Thymine B A C

  6. Rules for Base Pairing: They are called complementary base pairs A.Cytosine Guanine (C G) the lines between the letters are hydrogen bonds B.     Adenine = Thymine (A = T)

  7. Phosphate Nitrogen Bases Sugar C G A A T G

  8. Review QUESTIONS?? How many parts are there in a nucleotide? What is the simple sugar that makes up DNA? What pairs with A? What pairs with G?

  9. QUESTIONS??? Find the complementary DNA strand that matches the following bases ATGA = ____________ TTGC = ____________

  10. Fun Facts If you wrote down all of the bases in one cell, you would fill a stack of 1,000 phone books with A's, T's, G's and C's

  11. Fun Facts If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.

  12. DNA a double helix? Why do you think DNA is called a double helix?

  13. DNA Replication

  14. The DNA in the chromosome is copied in a process called DNA Replication DNA Replication

  15. During Replication, each strand serves as a pattern or template, to make a new DNA molecule just like the original Replication of DNA

  16. Question??? What is DNA Replication?

  17. An enzyme, DNA Helicase, comes on the scene UNWINDS the DNA upstream UNZIPS the DNA, breaking the hydrogen bonds Replication of DNA

  18. DNA Replication • All DNA strands are read from the 5’ to 3’ end • The 5’ end terminates in a phosphate group • The 3’ end terminates in a sugar molecule (deoxyribose)

  19. DNA Replication • Okazaki Fragments are short, newly synthesized DNA fragments that are formed on the lagging template strand (3’ to 5’ side) during DNA Replication

  20. DNA Replication • The leading strand is continuously built in the 5’ to 3’ direction • DNA polymerase can only add new nucleotides to a free 3’ end of a growing chain or the Lagging strands. These are discontinuous with Okazaki fragments coming in to fill in the gaps

  21. Biology Humor

  22. This process continues until the entire molecule has been unzipped and replicated. Each new strand formed is a complement of the original – part old, part new Replication of DNA

  23. Question Compare the 2 new strands formed through DNA Replication?

  24. DNA Review • Basic structure is made up of a nucleotide • Phosphate • Sugar • Deoxyribose • Nitrogen Base • A pairs with T • G pairs with C • DNA Replication • Copying of DNA • DNA Helicase unzips the DNA • Polymerase attaches the free nitrogen base • Works the leading strand (5’ to 3’) • Has to work backwards on the lagging strand (3’ to 5’) & fill in the gaps with Okazaki fragments

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