Ch. 12

DNA: the genetic material  Griffith , used a bacteria that causes pneumonia to figure out that there are smooth (S) strains and rough (R) strains, the S cells killed mice, while the R cells did not, a mixture of R and S Cells did however kill the mouse, he conclude that there was a transformation from R to S  Avery , identified molecule that transferred R into S  Hershey and Chase , discovered that DNA is the transforming factor by using Radioactive Labeling

Griffith’s Experiment

Hershey and Chase Experiment

DNA Structure  Nucleotides - subunits of nucleic acids, contain a 5-carbon sugar, a phosphate, and a nitrogenous base.  DNA  adenine (A), guanine (G), cytosine (C), and thymine (T)  RNA  adenine, guanine, cytosine, and uracil (U)  A and G are double rings so they are called Purine Bases  C, T and U are single rings called Pyrimidine Bases

Chargaff  Chargaff - found that the amount of G is equal to the amount of C, and A is equal to T  Chargaff's Rule - G=C, and A=T

Structure and Bases

DNA History Con’t  X-ray diffraction - used to figure out the shape of DNA (double helix)  Watson and Crick - Double Helix structure  1. two outside strands consist of alternating deoxyribose and phospate  2. cytosine and guanine bases pair to each other by three hydrogen bonds  3. thymine and adenine bases pair to each other by two hydrogen bonds  A purine always bonds to a pyrimidine base, so A=T and C=G Therefore, C+T = G+A

DNA Structure  Top rail goes from the 5' carbon on the left to the 3' carbon on the right ( 5'-3')  Bottom rail goes from the 3' carbon on the left to the 5' carbon on the right (3'-5')  Chromosome Structure  Human chromosomes have anywhere from 51 million to 245 million base pairs

DNA Replication  Semiconservative Replication - parental strands of DNA separate, serve as templates and produce DNA molecules that have one strand of parental DNA and one strand of new DNA  DNA Helicase - enzyme responsible for unwinding the DNA, breaks the Hydrogen bonds between the bases  When unzipped RNA primase adds a primer or starting point on each DNA strand  DNA Polymerase - enzyme that adds the nucleotides to the new DNA strand starting at the 3' end and then zips the strands back up

DNA Replication

DNA Replication Con’t  Chargaff's rule is demonstrated therefore there are exact copies of each other  Leading strand - strand that is copied as the DNA unwinds, built continuously  Lagging strand - replicates in the opposite direction as the DNA unwinds  Okazaki fragments - chunks nucleotides long on the lagging strand where replication takes place

DNA Replication

Nerdy Scientist Pick-Up Line

RNA  RNA - contains ribose (sugar), uracil (replaces thymine), and is usually single stranded  mRNA - messenger RNA, formed from one strand of a DNA molecule, they direct the synthesis of specific proteins  rRNA - ribosomal RNA, forms ribosomes in the cytoplasm  tRNA - transport RNA, smaller segments of RNA that transport amino acids to the ribosome

RNA  introns - sequences that are not coded for on the DNA molecule  exons - the sequences that are used in the code  DNA ultimately makes proteins, there are also 20 different amino acids that make up proteins  DNA sequences (codes) make up these amino acids  Codon - three base codes in DNA and mRNA that make up amino acids

Transcription  Transcription - DNA code is transferred to mRNA in the nucleus, then uses the code to synthesize proteins  Template strand - the strand of DNA that is copied by the RNA  Nontemplate strand - the strand of DNA that is not used by the RNA

Translation  Translation - once the mRNA is synthesized and processed, it moves to the ribosome, it attaches to the ribosome and the code is read and translated into proteins  tRNA - is basically an interpreter for the mRNA codon sequence  anticodon - three base coding sequence that is complimentary to the codon sequence

Amino Acids

What is the Sequence?  Start - Serine - Histidine - Tryptophan - Glycine - Stop  Start - Proline - Asparagine - Isoluecine - Valine - Glutamate - Stop  mRNA~  AUG - CCG - UUU - GGA - UGG - UGU - GGG - UAA

What is the Sequence Con’t  Amino Acids  tRNA  DNA

Terms  Gene regulation - ability of an organism to control which genes are transcribed in response to the environment  Operon - section of DNA that acts as an on/off switch for transcription  Mutation - permanent change occur in a cells DNA  point mutation - one base is exchanged for another (substitution)  Frame shift mutation - when a gain or a loss of a base  Duplication - when bases are duplicated  Expanding mutation - repetitive bases  Mutagen - Certain chemicals and radiation that can damage DNA sequences

Genetic Mutations

Test Info  TEST - 10 questions  Vocabulary with its definition  DNA Helicase, tRNA, DNA polymerase, Codon, rRNA, mRNA, genetic code, ribose, deoxyribose, RNA polymerase, anticodon, replication, transcription, translation, ribosomes, x-ray diffraction, and Hydrogen bond  Historical Contributions  Match the scientist with his/her contributions  Griffith, Avery, Hershey Chase, Franklin, Watson Crick, Chargaff  Comparing Molecules  Compare molecules of DNA, mRNA, and tRNA  know the structure!!!!!!!  Matching Codons  Fill in a table like we did in class  know the DNA, mRNA, tRNA, and the amino acid  Processes  Exactly from our notes  The process of DNA replication, transcription, and translation

Book Review  Review  Page 353 #’s: 3-5, 8-11,  Pg.354 #’s: 17, 18, 26-28, 30, 34 Pg #’s: 1-5, 9, 10, 12, 13, 16-18