BIOL 2050 1nd Edition Lecture 22Outline of Last Lecture I. Sex-Linked CharactersII. Rh FactorIII. Polygenic TraitsOutline of Current Lecture IV. DNAa. Research Methodsb. Structurec. ReplicationCurrent LectureDNA (Deoxyribonucleic Acid)- The substance of inheritance- Heredity information is encoded in DNA and reproduced in all cells of the body- Directs the development of biochemical, anatomical, physiological and behavioral traits.Research MethodsI. T.H. Morgan’s group showed that genes are located on chromosomesa. Didn’t what was genetic material; protein or DNAII. Frederick Griffith in 1928a. Discovered the genetic role of DNAb. He worked with two strains of bacteria c. Transformation: a change in genotype and phenotype due to assimilation of foreign DNA.d. Griffith mixed heat-killed remains of the pathogenic strain of bacteria with living cells of the harmless strain and some living cells became pathogenic.III. Hershey and Chase 1952a. Worked with a virusb. Bacteriaphages: form of viruses that infect bacteria and are widely used in molecular genetics research.c. Showed that DNA is the genetic material of this phageIV. Chargaff 1950These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Chargaff’s rules:i. DNA composition varies from one species to the nextii. In any species the number of A and T bases are equal and the number of G and C bases are equalStructureI. X-Ray crystallography was used to study the molecular structurea. Used by Maurice Wilkins and Rosalind Franklinb. Franklin produced a picture of the DNA moleculei. The pattern in the photo suggested that the DNA molecule was made of two strands forming a double helixii. She suggested that there were two outer sugar-phosphate backbones with nitrogenous bases paired in the interior.II. Watson and Cricka. Constructed a model of the double helix DNA from Rosalind’s photo.b. The backbones were antiparallelc. Paired a purine with a pyrimidine and this resulted in a uniformed width that was consistent with the photod. Pairing was more specific i. A pairs with Cii. C pairs with GReplicationI. The two strands making the double helix are separate, therefore they can each act as a template for building a new strandII. DNA Replication: the parent molecule unwinds and two new daughter strands are built based on the base-pairing rulesIII. Semiconservative Model: when a double helix replicates, each daughter molecule will have one new strand and one old strand.IV. Replication Processa. Copying of DNA is remarkably fastb. More than a dozen enzymes take partc. Origin of replication: where the two DNA strands are separated and open a replication bubble.d. Replication proceeds in both directionse. Replication Fork: a Y-shaped region where new DNA strands are elongatingf. Helicases: enzymes that untwist the double helix at the forksg. Single-strand binding proteins: bind to and stabilize single-strand DNAh. Topoisomerase: corrects overwinding ahead of replication forks bybreaking, swiveling and rejoining DNA strandsi. DNA Polymerase: catalyzes the elongation of new DNA at a replication
View Full Document
Unlocking...