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First Five 2/10

First Five 2/10 Without using your lab, who were the people, in order, that discovered the structure of DNA? Turn in your lab notebook to the bin behind Kringle’s computer. Schedule First Five DNA notes HW: Discovering DNA Lab – Due Today DNA Molecule/Replication wkst – due Friday

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First Five 2/10

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  1. First Five 2/10 • Without using your lab, who were the people, in order, that discovered the structure of DNA? • Turn in your lab notebook to the bin behind Kringle’s computer. • Schedule • First Five • DNA notes • HW: • Discovering DNA Lab – Due Today • DNA Molecule/Replication wkst – due Friday • GQ2: How does DNA’s structure relate to its function?

  2. Schedule • First Five • Finish Movie • Letter Assignment • HW: Letter Due Friday • GQ: How does DNA’s structure relate to its function? First Five 2/4 • Who do you think contributed the most to the discovery of DNA’s structure and Why? - Watson/Crick - Franklin - Wilkins - Pauling - Chargaff 2. Turn in your lab notebook to the bin behind Kringle’s computer.

  3. Choose one of the following letters to write. • Write a letter to James Watson as Rosalind Franklin, detailing your disappointment for not receiving credit for providing pertinent information for DNA’s structure. • Write a letter to Rosalind Franklin as Maurice Wilkins, detailing why Franklin should have received credit for DNA’s structure. • Write a letter to the Nobel Prize committee as Rosalind Franklin, detailing your contributions to Watson and Crick’s discovery of DNA structure.

  4. Schedule • First Five • Quiz – Cell Cycle • Replication Notes • Replication Lab • HW: DNA Molecule – Due Thurs • DNA Replication – Due Thurs • GQ: How is DNA replicated? First Five 2/4 • Without your movie notes; what did the following people discover about DNA’s Structure? - Watson/Crick - Franklin - Wilkins - Pauling - Chargaff

  5. 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 phosphate group nitrogen-containing base deoxyribose (sugar) DNA is composed of four types of nucleotides.

  6. The nitrogen containing bases are the only difference in the four nucleotides.

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

  8. Watson and Crick’s discovery built on the work of Rosalind Franklin and Erwin Chargaff. • Franklin’s x-ray images suggested that DNA was a double helix of even width. • Chargaff’s rules stated that A=T and C=G.

  9. KEY CONCEPT DNA replication copies the genetic information of a cell.

  10. Remember that a cell’s DNA needs to replicate (duplicate) before the cell can divide. Write a hypothesis proposing how DNA replicates.

  11. G C A T Nucleotides always pair in the same way. • Chargaffs Rules: • #A = #T • #G = #C • The base-pairing rules show how nucleotides always pair up in DNA. • A pairs with T • C pairs with G • Because a pyrimidine (single ring) pairs with a purine (double ring), the helix has a uniform width.

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

  13. Replication copies the genetic information. • A single strand of DNA serves as a template for a new strand. • The rules of base pairing directreplication. • DNA is replicated during theS (synthesis) stage of thecell cycle. • Each body cell gets acomplete set ofidentical DNA.

  14. Schedule • First Five • Replication Notes • Replication Lab • HW: DNA Molecule – Due Tomorrow • DNA Replication – Due Tomorrow • Cell Cycle Quiz Make up – Due Friday • GQ: How is DNA replicated? First Five 2/5 • What is the monomer of DNA? • Write a hypothesis as to how DNA is replicated.

  15. nucleotide The DNA molecule unzips in both directions. Proteins carry out the process of replication. • DNA serves only as a template. • Enzymes and other proteins do the actual work of replication. 1. Enzymes unzip the double helix. (Helicase) 2. Free-floating nucleotides form hydrogen bonds with the template strand.

  16. nucleotide new strand DNA polymerase • 3. DNA polymerase enzymes bond the nucleotides together in the new strand (covalent bonds between sugars and phosphates) to form the double helix. • DNA Polymerase fixes misplaced nucleotides in the new strand.

  17. new strand original strand Two molecules of DNA • Two new molecules of DNA are formed, each with an original strand and a newly formed strand. • DNA replication is semiconservative.

  18. There are many origins of replication in eukaryotic chromosomes. Replication is fast and accurate. • DNA replication starts at many points in eukaryotic chromosomes. • DNA polymerases can find and correct errors.

  19. Schedule • First Five • Replication Lab/ Oral Quizzes • Clean Up • HW: DNA Molecule – Due Today • DNA Replication – Due Today • Cell Cycle Quiz Make up – Due Friday • Test/Test Packet – Due Thurs 2/13 • Review – Due Wednesday 2/12 • GQ: How is DNA replicated? First Five 2/6 • What two enzymes are involved in replication? • Take out your DNA molecule and DNA Replication wksts.

  20. Questions • In step 1 of replication, how does the DNA unzip? • In step 2 of replication, how do the new strands compare with the template strands? • What enzyme is important in step 2? • What is the result of DNA replication? • Why is it important for the cell to correct any errors that occur during replication?

  21. Oral Quiz • What do we mean when we say that DNA replication is semiconservative? • What are the three steps of DNA replication? What happens in each step? • What type of molecule creates the bonds between the sugars and the phosphates of the new nucleotides? What type of bond is formed? • What do we call the location where DNA replication begins? • Where do the free-floating nucleotides come from?

  22. Why do cells need to divide? Replace old and damaged cells Big cells begin to starve and lack Oxygen Big cells cannot get rid of waste or CO2 fast enough

  23. DNA andhistones SupercoiledDNA DNA doublehelix Chromatin Chromosomes condense at the start of mitosis. • DNA wraps around proteins (histones) that condense it.

  24. chromatid telomere centromere telomere Condensed, duplicated chromosome • One half of a duplicated chromosome is a chromatid. • Sister chromatids are held together at the centromere. • Telomeres protect DNA and do not include genes. • DNA plus proteins is called chromatin.

  25. Human Cells have 23 pairs of chromosomes (total 46) • Homologous chromosomes • Two chromosomes that have copies of the same genes

  26. Duplicated vs. Unduplicated Homologous Chromosomes

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