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Notes ch12 DNA

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DNA has three main functions: storing genetic information, copying that information during cell division, and transmitting the information to offspring. DNA is made up of nucleotides containing a sugar, phosphate, and one of four nitrogenous bases. Rosalind Franklin discovered that DNA has a double helix structure with the bases on each strand bonding with their complement on the other strand in a regular pattern. Watson and Crick were the first to model DNA as a double helix with antiparallel strands held together by hydrogen bonding between complementary nucleotide base pairs. DNA replication copies the DNA before cell division, unwinding the double helix and using DNA polymerase to add complementary bases to each strand.

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Chapter 12: DNA
12.1 The Role of DNA DNA has 3 functions: Storing information Copying information Transmitting information
12.2 The Structure of DNA DNA deoxyribonucleic acid Nucleotides monomers that make up a DNA molecule 3 parts: 5 Carbon sugar (deoxyribose) Phosphate group Nitrogenous base Adenine (A) Guanine (G) Cytosine (C) Thymine (T)
Solving the Structure of DNA Edwin Chargaff (1949) Chargaffs Rule [A]=[T] [C]=[G] Adenine Thymine Guanine Cytosine 35% 45%
Rosiland Franklin used X-ray diffraction to visualize DNA structure (1952).
Watson and Crick were the first to model DNA as a double helix in 1953.
The Double Helix Model All the previous discoveries show us the structure of DNA and how DNA can function as a carrier of genetic information. Characteristics of the double helix model: Antiparallel strands Hydrogen Bonding Base Pairing
Antiparallel Strands Run in opposite directions Base Pairing Bases are held together by hydrogen bonds. Base Pairing A bonds with T, and C bonds with G Complimentary base pairs hydrogen bond covalent bond
Practice Base Pairing If the sequence of bases on one strand of a DNA molecule is TCGAACTGA, the sequence on the other (complimentary) strand is:
12.3 DNA Replication Why does DNA replicate? (Hint: Think back to Mitosis) DNA is replicated in the S phase of the cell cycle, before the cell divides.
Copying the Code Step 1 The DNA double helix unwinds DNA helicase (enzyme). breaks the H bonds between the bases. The areas where the double helix separates are called replication forks.
Step 2 DNA polymerase (enzyme) moves along each DNA strand adding complimentary bases according to the base pairing rules. DNA polymerase also proofreads the DNA molecule to reduce errors.
Step 3 The process continues until all of the DNA has been copied. DNA polymerase detaches.
This process produces two DNA molecules each composed of one new and one original strand. Both DNA molecules produced are identical to each other. DNA replication takes place at many points on a eukaryotic chromosome. Allows replication to happen more quickly.

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Notes ch12 DNA

  • 2. 12.1 The Role of DNA DNA has 3 functions: Storing information Copying information Transmitting information
  • 3. 12.2 The Structure of DNA DNA deoxyribonucleic acid Nucleotides monomers that make up a DNA molecule 3 parts: 5 Carbon sugar (deoxyribose) Phosphate group Nitrogenous base Adenine (A) Guanine (G) Cytosine (C) Thymine (T)
  • 4. Solving the Structure of DNA Edwin Chargaff (1949) Chargaffs Rule [A]=[T] [C]=[G] Adenine Thymine Guanine Cytosine 35% 45%
  • 5. Rosiland Franklin used X-ray diffraction to visualize DNA structure (1952).
  • 6. Watson and Crick were the first to model DNA as a double helix in 1953.
  • 7. The Double Helix Model All the previous discoveries show us the structure of DNA and how DNA can function as a carrier of genetic information. Characteristics of the double helix model: Antiparallel strands Hydrogen Bonding Base Pairing
  • 8. Antiparallel Strands Run in opposite directions Base Pairing Bases are held together by hydrogen bonds. Base Pairing A bonds with T, and C bonds with G Complimentary base pairs hydrogen bond covalent bond
  • 9. Practice Base Pairing If the sequence of bases on one strand of a DNA molecule is TCGAACTGA, the sequence on the other (complimentary) strand is:
  • 10. 12.3 DNA Replication Why does DNA replicate? (Hint: Think back to Mitosis) DNA is replicated in the S phase of the cell cycle, before the cell divides.
  • 11. Copying the Code Step 1 The DNA double helix unwinds DNA helicase (enzyme). breaks the H bonds between the bases. The areas where the double helix separates are called replication forks.
  • 12. Step 2 DNA polymerase (enzyme) moves along each DNA strand adding complimentary bases according to the base pairing rules. DNA polymerase also proofreads the DNA molecule to reduce errors.
  • 13. Step 3 The process continues until all of the DNA has been copied. DNA polymerase detaches.
  • 14. This process produces two DNA molecules each composed of one new and one original strand. Both DNA molecules produced are identical to each other. DNA replication takes place at many points on a eukaryotic chromosome. Allows replication to happen more quickly.