GCD Lecture 2

• Frederick Griffith (1928): Living type R cells and dead S cells keep mice alive. Live R cells combined with dead S cells and live S cells will kill mice.
• Avery, Macleod, McCarthy (1944): Added protein, DNA, and RNA (from S cells) to R cells. DNA was the only gene that turned R cells into S cells, concluding that genes are made of DNA
• Hershey and Chase (1952): infected cells with either phosphorus or sulfur, after blending and centrifugation, it was shown that DNA entered the cell, while protein did not. Therefore it was confirmed that DNA is genetic material
• both DNA and RNA nucleotides consist of a phosphate, a sugar, and a base (A, T, G, or C)
• Edwin Chargaff: when any DNA molecule was cleaved into nucleotides, it produced the same amount of nucleotides A and T and the same amount of nucleotides G and C. However, the (G+C) amount alwaysdiffered from the (A+T) amount.
• Rosalind Franklin: passed X-rays through DNA fibers and concluded that the DNA molecule was helical
• Hydrogen bond: takes three atoms to make, partial negative charges of O and N attract H with partial positive charges.
• James Watson and Francis Crick: noticed if A and G bases were rotated 180 degrees they could H bond to T and C bases, when phosphate of one nucleotide and sugar link the strands form a helix
• sugar in RNA or RNA nucleotides is called ribose
• the sugar in DNA or DNA nucleotides is called deoxyribose because an oxygen is missing from the 2’ carbon of the sugar
• the only difference between the bases in RNA and DNA is the presence of a methyl group in the T nucleotide and having the U nucleotide missing from DNA
• the extra oxygen in RNA makes RNA incapable of forming a Bhelix
• phosphate in DNA and DNA nucleotides is attached to the 5’ carbon of the sugar
• the base in DNA and DNA nucleotides is attached to the 1’carbon of the sugar
• a gene is a section of the DNA in a chromosome that gets copied into RNA by RNA polymerase
• RNA copy is called a transcript and that this manner of RNA synthesisis called transcription (using a DNA strand as a template)
• coding strand: the strand that carries the genetic code for the protein
• template DNA strand: a DNA strand that is complementary to the template RNA strand
• RNA polymerase gets loaded on the gene at the promotor
• a gene ends at a termination signal
• the stronger the promotor, the more RNA copies of the genewill be made