2. Watson and Crick – 1 st to propose structure of DNA. Requires precise transmission during replication.

3. http://www.ncbe.reading.ac.uk/DNA50/Resources/wc1993.gif

4. Prior to Watson, Griffith tested transmission. Griffith - injected live bacterial strains into mice. Mixed R strain of bacteria (harmless) with heat-killed S strain (harmful) and injected it. After mouse died, removed strain from mouse.

6. Substance eventually found to be DNA - supported by injecting bacteria into viruses. Viruses consist of DNA (sometimes RNA) enclosed by protective coat of protein. To replicate - virus infects host cell; takes over cell’s metabolic machinery. Viruses that specifically attack bacteria - bacteriophages (phages)

7. http://www.monografias.com/trabajos5/virus/Image164.gif

8. Transformation - change in genotype and phenotype due to assimilation of foreign substance (now DNA) by cell.

9. http://www.swbic.org/products/clipart/images/bacteriophage.jpg

10. Hershey and Chase labeled protein and DNA - injected them into bacteria. Hershey and Chase concluded that DNA, not protein, is responsible for transmission. DNA doubles prior to mitosis.

12. 1940’s - DNA made of bases (adenine, thymine, cytosine, guanine) Also known that sugar of one nucleotide attached to phosphate of another - forms backbone of DNA. Chargaff’s rules - even amount of thymine and adenine. (and guanine and cytosine)

14. Watson 1 st to figure DNA in helix shape + specific distance between nucleotides. Partnered with Crick – came up with double stranded model of DNA - double helix.

15. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 16.5

16. Found purine (A, G) has to pair with pyrimidine (T, C) to achieve distance needed. Knew A - T (2 H bonds), C - G (3 H bonds

19. Each gene found to have unique sequence of nitrogen bases - DNA strands not all the same.

20. http://academy.d20.co.edu/kadets/lundberg/dna_wallpaper/dna800x600.jpg

21. Each strand of DNA can be template to make more DNA. Cell copies DNA - each strand forms as template to determine new complementary bases. Nucleotides pair in complementary fashion, one by one.

23. Semiconservative replication - each DNA molecule has one parent strand and one daughter strand.

25. Even though process is amazingly quick, only about 1 in a billion nucleotides copied wrong. Proteins and enzymes also part of process, not just nucleotides.

26. http://www.bio.miami.edu/dana/250/nucleotides.jpg

27. Origins of replication - where replication begins. Bacteria - 1 site - replication is bubble moving along DNA. Eukaryotes - many origins of replication on each chromosome. Origin sites - DNA strands separate forming replication “bubble” with replication forks at each end.

29. Elongation of DNA catalyzed by 1 DNA polymerase. Polymerase adds complementary bases to growing strand of new DNA. 2 Helicase - untwists double helix of DNA at replication fork. 3 Single-strand binding proteins help keep strands apart from one another during replication.

31. Strands of DNA - antiparallel. Sugar-phosphate backbones run in opposite directions. Each end of strand labeled either 5 ’ end or 3 ’ end.

33. Nucleotides only be added to 3 ’ end. DNA strand can only elongate from 5 ’ end to 3 ’ end. Replication fork - problem - system because strands run in opposite directions (antiparallel)

34. http://www.mie.utoronto.ca/labs/lcdlab/biopic/fig/11.16.jpg

35. 1 parent strand (leading strand - one that runs 3’ to 5’) used as template to keep complementary strand continuous. Other strand (lagging strand - one that runs 5’ to 3’) copied from fork in small segments - Okazaki fragments.

36. http://www.biology.arizona.edu/molecular_bio/problem_sets/nucleic_acids/graphics/repfork1.gif

37. Fragments “ glued ” together by 4 DNA ligase to form backbone (made of sugar and phosphate) of single DNA strand.

39. Polymerase adds nucleotides to strands, cannot start whole process. Done by a piece of RNA - primer.

40. http://www.biologie.uni-hamburg.de/b-online/library/bio201/primase.jpg

41. Once primer formed, polymerase adds DNA nucleotides to growing daughter strand of DNA. After, 5 DNA polymerase (different) replaces original RNA with new complementary DNA nucleotides - no RNA left in strand.

44. Replication fork, leading strand copied continuously into fork from single primer. Lagging strand copied away from fork in short segments, each requiring new primer.

46. Original errors in reading of template occur. Enzyme (DNA polymerase) removes mistake and replaces it. Some things can alter DNA outside of body.

47. http://library.thinkquest.org/C0123260/basic%20knowledge/images/basic%20knowledge/DNA/polymerase%201.jpg

48. X-rays, UV rays can alter DNA after replication. Mistakes can be fixed after DNA synthesis - cell continually monitors DNA. 1 Mismatch repair - special enzymes fix incorrectly paired nucleotides - happens in certain types of cancers.

49. http://www.sinauer.com/cooper4e/sample/Figures/Chapter%2006/highres/CELL4e-Fig-06-24-0.jpg

50. 2 Nucleotide excision repair - nuclease cuts out segment of damaged strand. Xeroderma pigmentosa (genetic disease) cannot go through process. Disease prevents person from going in sun - UV rays interfere with DNA replication (more susceptible to skin cancer - can’t fix mistakes)

52. http://162.129.70.33/images/xeroderma_pigmentosa_2_040620.jpg

53. Ends of DNA strand can break down from constant replication. Ends of chromosomal DNA molecules – telomeres - special nucleotide sequences. Telomeres protect genes from being eroded through multiple rounds of DNA replication.

55. When telomeres shorten, telomerase uses piece of RNA to lengthen telomere. Telomerase has life span to certain tissues or organism. Important for telomerase to be in gamete cells so they can pass long telomeres on to zygote. Active telomerase in body cells can be responsible for cancer cells because cells keep dividing.

56. Proteins - link between genotype (what DNA says) and phenotype (physical expression) Beadle and Tatum – 1 st to make connection between genes and enzymes that carry out genes (bread mold experiments)

57. http://fig.cox.miami.edu/~cmallery/150/gene/17x3.jpg

58. Bridge between DNA, proteins - RNA. RNA similar to DNA - sugar ribose; contains uracil instead of thymine. RNA single-stranded.

59. http://gibk26.bse.kyutech.ac.jp/jouhou/image/nucleic/rna/rna_bb_st.gif

60. Nucleotides found in DNA and RNA - code - determines order of amino acids. 2 steps - transcription and translation. Transcription - DNA serves as template for complementary RNA strand.

61. http://www.ktf-split.hr/glossary/image/nucleotide.gif

62. Transcription produces mRNA strand (messenger RNA). Translation uses mRNA sequence to determine order of amino acids - creates polypeptide.

63. http://www.brooklyn.cuny.edu/bc/ahp/BioInfo/graphics/Transcription.02.GIF

64. Bacteria - transcription and translation occur at once. Eukaryotes, most transcription occurs in nucleus, translation occurs at ribosome. Before primary transcript can leave nucleus - modified during RNA processing before enters cytoplasm.

67. Genetic code - triplet code - series 3 nitrogen bases that code for specific amino acid. 64 possible combinations of nitrogen bases. Only 20 amino acids = each amino acid has more than 1 code.

68. http://www.dls.ym.edu.tw/lesson/gen.files/codon.jpg

69. 61 of 64 codes specific to an amino acid. Other 3 - stop codons - determine when process stops. Specific code that signals start of translation - also codes for amino acid. Start begins correct reading frame of polypeptide.

71. Transcription, 1 DNA strand - template strand, provides template for ordering sequence of nucleotides in RNA transcript. Translation, blocks of 3 nucleotides, codons, decoded into sequence of amino acids.

73. Possible to take genetic code of 1 organism, place it into another - nearly universal. Firefly gene for luminescence transplanted into tobacco plant. Bacteria can be inserted with specific genes to synthesize genes in large amounts.

75. Synthesis and Processing of RNA mRNA transcribed from template of original gene. RNA polymerase separates DNA strands and bonds RNA bases along complementary strand. Bases can only be added to 3 ’ end.

76. http://www.csu.edu.au/faculty/health/biomed/subjects/molbol/images/7_9.jpg

77. Specific sequences determine where transcription starts and where it ends. Promoter sequence – initiates; terminator ends.

79. Presence of promotor determines which strand of DNA helix is template. Proteins (transcription factors) recognize promotor region (TATA box) and bind to promotor.

80. http://www.nslij-genetics.org/pic/promoter.gif

81. After binding, RNA polymerase binds to transcription factors. RNA polymerase starts transcription.

83. RNA polymerase moves along - nucleotides added to 3’ end. Single gene can be transcribed simultaneously by several RNA polymerases at a time. Growing strand of RNA trails off from each polymerase.

85. RNA splicing - removal of large portion of RNA molecule because most eukaryotic genes and RNA transcripts have long noncoding (introns) stretches of nucleotides between coding regions (exons)

86. http://ghs.gresham.k12.or.us/science/ps/sci/ibbio/chem/nucleic/chpt15/introndeletion.gif

87. RNA splicing removes introns, joins exons to create mRNA molecule with continuous coding sequence. Splicing done by spliceosome.

90. Translation - cell interprets codons along mRNA molecule. Transfer RNA (tRNA) transfers amino acids from cytoplasm’s pool to ribosome. Ribosome adds each amino acid carried by tRNA to growing end of polypeptide chain.

92. tRNA links mRNA codon with amino acid. tRNA arriving at ribosome carries specific amino acid at 1 end, has specific nucleotide triplet, anticodon, at other. Anticodon base-pairs with complementary codon on mRNA.

93. http://bioweb.uwlax.edu/GenWeb/Molecular/Theory/Translation/ribosome.jpg

94. tRNA synthesized like other forms of RNA. Once in cytoplasm, each tRNA used repeatedly to pick up and drop off that amino acid.

96. Anticodons recognize more than one codon. Rules for base pairing between 3 rd base of codon and anticodon relaxed (wobble).

97. http://www.geneticengineering.org/chemis/Chemis-NucleicAcid/Graphics/tRNA.jpg

98. Each ribosome has 3 binding sites for tRNA molecules. P site holds tRNA carrying growing polypeptide chain. A site carries tRNA with next amino acid. Discharged tRNAs leave ribosome at E site.

100. http://nobelprize.org/educational_games/medicine/dna/a/translation/pics/translation2.gif

101. 1 Initiation brings together mRNA, tRNA with 1 st amino acid. 2 Elongation - each amino acid added to previous one. 3 steps of elongation continue codon by codon to add amino acids until polypeptide chain completed.

103. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 17.18

104. 3 Termination - 1 of 3 stop codons reaches A site. Release factor binds to stop codon, breaks bond between polypeptide and tRNA in P site - frees polypeptide.

106. 2 types of ribosomes active in process. 1 Free ribosomes suspended in cytosol synthesize proteins in cytosol. 2 Bound ribosomes attached to endoplasmic reticulum.

107. Fig. 17.21 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

108. Bacteria and eukaryotes have differences in details of processes. Eukaryotic RNA polymerases differ from prokaryotic; require transcription factors.

109. Differ in how transcription terminated. Ribosomes also different. Prokaryotes can transcribe and translate same gene simultaneously.

111. Mutations - changes in genetic material of cell (or virus). Chemical change in 1 base pair of gene causes point mutation. Occur in gametes or cells producing gametes - may be transmitted to future generations.

112. http://staff.jccc.net/PDECELL/evolution/mutations/mutypes.gif

113. If it results in replacement of pair of complementary nucleotides with another nucleotide pair - base-pair substitution. Can have little or no impact on protein function (silent mutations).

114. http://fajerpc.magnet.fsu.edu/Education/2010/Lectures/26_DNA_Transcription_files/image008.jpg

115. Missense mutations - code for different amino acid. Nonsense mutations - code for “ stop ” - leads to malfunctioning protein.

116. Fig. 17.24 Copyright © Pearson Education, Inc., publishing as Benjamin Cummings

117. Insertions and deletions - additions or losses of nucleotide pairs in gene. Unless these mutations occur in multiples of 3 - cause frameshift mutation.

118. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 17.24

119. Mutations can occur in many ways - during DNA replication, DNA repair, or DNA recombination. Mutagens - chemical or physical agents that interact with DNA to cause mutations (high-energy radiation - X-rays UV light).