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What am I?

What am I?. I'm called by three letters Though I have a long name. I'm in all of you, But I'm never the same. I'm all coiled up So that I am quite small, But if you stretch me out I'll be really tall. I could be the root  Of certain disease; If man can unlock me He'll solve many mysteries.

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What am I?

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  1. What am I? I'm called by three lettersThough I have a long name.I'm in all of you,But I'm never the same.I'm all coiled upSo that I am quite small,But if you stretch me outI'll be really tall.I could be the root Of certain disease;If man can unlock meHe'll solve many mysteries.

  2. Which of the 4 types of macromolecules is DNA? • Carbohydrates • Lipids • Nucleic Acids • Proteins Nucleic Acid!

  3. DNA • Remember! DNA is 1 of the 4 types of macromolecules (nucleic acid)! • Deoxyribonucleic Acid

  4. Remember that the 4 macromolecules are polymers, meaning they are made of monomers bonded together. What is the monomer of DNA? • Monosaccharides • Fatty Acids • Amino Acids • Nucleotides Nucleotides!

  5. Which types of cells contain DNA? • Eukaryotic • Prokaryotic • All of the above • None of the above All of the above! ALL living things (prokaryotes & eukaryotes) contain DNA!

  6. Where is DNA found in Eukaryotic cells? • Cytoplasm • Lysosomes • Nucleus • Vacuole Nucleus!

  7. DNA Structure

  8. What does DNA do? • DNA can: • Carry genetic information from one generation to the next (genes are made of DNA) • Be easily and accurately copied before cell division

  9. What is the monomer of DNA? • Nucleotide!

  10. Nucleotides – 3 Parts • a 5-carbon sugar called deoxyribose • a phosphate group • a nitrogenous base

  11. Nucleotides • Two types of nucleotides: • Purines • Pyrimidines • Purines: two rings • Adenine (A) • Guanine (G)

  12. Nucleotides • Pyrimidines: one ring • Cytosine (C) • Thymine (T)

  13. Nucleotides • When nucleotides bind together, they form a chain, which is the polymer DNA! • The sugar & phosphate groups form the backbone of the chain (like the sides of a ladder). • The nitrogenous bases stick out from the chain (like the rungs of a ladder).

  14. Each strand of DNA has directionality! • Each molecule will have a phosphate, or a 5’ end (5 prime) and a sugar, or a 3’ end (3 prime).

  15. DNA looks like a twisted ladder! The strands run in opposite directions, called antiparallel (like opposite flows of traffic).

  16. One strand runs 5’ to 3’ while the other strand runs 3’ to 5’. 5’ 3’ 3’ 5’

  17. Base Pairing Rules! • Each base pair is made of 1 purine & 1 pyrimidine! • Adenine from 1 strand and thymine from the other always pair together with 2 hydrogen bonds. • Guanine from 1 strand and cytosine from the other always bond together with 3 hydrogen bonds.

  18. A T A A A T T T C C C G G G

  19. What will the opposite strand look like? 5’-ATGGTTCCA-3’ 3’-TACCAAGGT-5’

  20. Chargaff’s Rules • Erwin Chargaff (1905-2002) discovered that in any DNA sample the amount of guanine is always equal to the amount of cytosine, and the amount of adenine was always equal to the amount of thymine. A = T G = C

  21. If adenine (A) makes up 35% of a DNA molecule, what percentage of the molecule is thymine (T)? • 70% • 35% • 15% • Not enough info. 35%

  22. If adenine (A) makes up 35% of a DNA molecule, what percentage of the molecule is guanine (G)? • 70% • 35% • 15% • Not enough info. 15%

  23. X-Ray Evidence (1952) • Rosalind Franklin studied the DNA molecule using x-ray diffraction (bending of waves around an edge or barrier) to see the structure of DNA. • From her work she was able to see that the DNA strands were twisted around each other forming a helix!

  24. The Double Helix Model (1953) • Francis Crick and James Watson were trying to figure out the structure of DNA by building models with cardboard and wire. • When they saw Franklin’s pictures they soon were able piece all the information together to come up with the 3-dimensional structure of DNA: a double helix with two strands winding around each other.

  25. Fun Facts! The DNA in just 1 of your cells is about 3 meters long! The DNA in all of your cells combined is twice the diameter of our solar system and could go from Earth to the sun 340 times! So how does DNA fit inside of our cells?

  26. DNA molecules are SUPER LOOOOOONG! In order to fit into our cells, they must fold up as much as possible!

  27. Chromosomes

  28. DNA & Chromosomes • In Eukaryotic cells, the DNA is bound to histone proteins, forming chromatin in the nucleus. DNA + Proteins = Chromatin

  29. How does DNA fit in the cell? • It is supercoiled! Meaning, the DNA & histone proteins are packed tightly together to make them fit.

  30. DNA + Proteins = Chromatin Tightly Packed Chromatin = Chromosome

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