Lab Biology- Chapter 10 Honors Biology- Chapter 9

 Found on chromosomes  Segment of DNA  Codes for a trait

 Characteristic due to a single gene or multiple genes  Eye color  Hair color  Blood type

 Deoxyribose sugar  Phosphate group  Nitrogen containing base ◦ Four possible bases

 2 rings of carbon and nitrogen  Adenine  Guanine

 1 ring of carbon and nitrogen atoms  Thymine  Cytosine

 DNA is composed of 2 nucleotide chains  Nucleotides connected through covalent bonds

 Each strand has a 5’ and a 3’ end  Each strand runs in an opposite (antiparallel) direction

 Nucleotide linkage  Covalent bonds between sugar and phosphate molecules  Forms a sugar- phosphate backbone 5’ 3’

 Covalent bond  Chemical bonding through sharing of electron pairs

 Purine Pyrimidine  A T – 2 Hydrogen bonds  C G – 3 Hydrogen bonds

 Hydrogen bonding between base pairs  Hydrogen atom - electronegative atom

 Hydrogen bonds?  Covalent bonds?

 Chargaff’s rule  The DNA of any given species contains ◦ adenine = thymine ◦ guanine = cytosine

 Wilkins and Franklin  Used X-ray diffraction ◦ A picture of how X-rays bounced off a DNA molecule FranklinWilkinsX-ray diffraction

 X-Ray diffraction  Used to determine arrangement of atoms within a crystal structure  Distance between dark spots- distance between turns of the helix

 Performed no physical experiments on DNA  Spent a lot of time thinking about DNA  Focused on creating a model that fit with the data

 Wilkins, Watson, and Crick received the Nobel Prize in 1962  Franklin died in 1958 and was not recognized  Nobel Prize cannot be awarded posthumously

 Write a two paragraph reflection on Rosalind Franklin. ◦ One paragraph should detail her contribution to the discovery of the structure of DNA. ◦ Second paragraph should state your answer to the questions:  Do you think Franklin deserved the Nobel Prize?  Why do you think she did not receive more recognition? ◦ Evidence must be provided to support your opinions. ◦ Complete this assignment on loose leaf paper.

 Occurs in all living organism  Takes place in the nucleus  One double stranded molecule two identical copies Original strand New strand

 Helicase (enzyme) holds the two strands apart ◦ Break hydrogen bonds between bases

 Replicates simultaneously

 DNA polymerase synthesizes DNA by adding nucleotides in a 5’ 3’ direction  Leading strand- continuous ◦ Moves in the direction of unwinding  Lagging strand- discontinuous

 Lagging Strand  Discontinuous  Forms in the opposite direction of replication fork  Creates Okazaki fragments  Must wait for a new primer to be placed

 DNA Primase- lays down short segments of RNA primer  DNA Polymerase III- adds new nucleotides  DNA ligase- bonds Okazaki fragments together

 Semiconservative model

 What happens when DNA Polymerase makes a mistake?  Mutation- Change in nucleotide sequence  Can be repaired through DNA repair mechanisms

 One nucleotide is substituted for another  Sickle Cell Anemia

 A nucleotide is deleted  Cystic fibrosis ◦ Deletion of "AT" from the sequence "ATAT" in the CFTR gene  Causes a frameshift

 A nucleotide is added  Huntington’s disease  Causes a frameshift

 DNA segment is broken and flipped  No frameshift  No loss of genetic information  Different order  Hemophilia

 Part of the gene is moved ◦ Either moved on the same chromosome or moved to a different chromosome  A form of Down syndrome  Part of Chromosome 21 is moved to Chromosome 14

 DNA Replication Game  cine/dna_double_helix/dnahelix.html cine/dna_double_helix/dnahelix.html  Honors: DNA Replication  /student/animations/dna_replication/in dex.html /student/animations/dna_replication/in dex.html  DNA Replication:  rombonefinald.swf rombonefinald.swf