GENETIC INFORMATION - 1. OVERVIEW Storage of Genetic Information Structure of DNA Ch 9 Making Copies of Genetic Information Replication of DNA Ch 9 – DNA Ch 11 & 12 - Cells Using Genetic Information to Make Cell Structures and Regulate Energy Use Process of Gene Expression Ch 10 An Overview of Information Flow in a Cell Gene Transcription DNA => RNA Translation RNA => Protein Proteins – cell structures & tools (F10.8, p. 175) Copyright © 2005 Pearson Prentice Hall, Inc.

Copyright © 2005 Pearson Prentice Hall, Inc. transcription rRNA + proteins mRNA tRNA ribosomes tRNA amino acids translation Figure :10-8 Title: An overview of information flow in a cell, from gene transcription to chemical reactions catalyzed by enzymes Caption: modification degradation Copyright © 2005 Pearson Prentice Hall, Inc.

Figure: 9-UO Title: Inheritance Caption: Inheritance provides for both similarity and difference. All dogs share many similarities because their genes are nearly identical. The enormous variety of body size, fur length and color, and proportion among breeds results from tiny differences in their genes.

Chapter 9 DNA: The Molecule of Heredity Copyright © 2005 Pearson Prentice Hall, Inc.

Discovery That Genes Are Made of DNA Transformed Bacteria Revealed the Link Between Genes & DNA Transformed bacteria (F9.1 p. 150) Unnumbered Figure 1 Pyrimidine nucleotides (p. 151) Unnumbered Figure 2 Purine nucleotides (p. 151) Copyright © 2005 Pearson Prentice Hall, Inc.

Bacterial strain(s) injected into mouse Results Conclusions R strain does not cause pneumonia. Living R strain S strain causes pneumonia. Living S strain Figure :9-1 Title: Transformed bacteria Caption: Griffith's discovery that bacteria can be transformed from harmless to deadly laid the groundwork for the discovery that DNA contains genes. Question If Griffith had used malaria, which is caused by a single-celled eukaryote, instead of pneumonia, would his experiment have had the same result? Heat-killed S strain does not cause pneumonia. Heat-killed S strain A substance from heat-killed S strain can transform the harmless R strain into a deadly S strain. Living R strain, heat-killed S strain

Structure of DNA DNA: Composed of Four Nucleotides DNA: Double Helix of Two Nucleotide Polymers X-ray diffraction of DNA - Rosalind Franklin (F9.2 p. 152) Watson-Crick model of DNA structure (F9.3 p. 153) The discovery of DNA (FE9.1 p. 154) Copyright © 2005 Pearson Prentice Hall, Inc.

phosphate base = adenine sugar phosphate sugar base = guanine Figure: 9-UN2 Title: Purine nucleotides phosphate sugar base = guanine

Figure :9-2 Title: X-ray diffraction studies of DNA taken by Rosalind Franklin Caption: (a) The X formed of dark spots is characteristic of helical molecules such as DNA. Measurements of various aspects of the pattern indicate the dimensions of the DNA helix; for example, the distance between the dark spots corresponds to the distance between turns of the helix. (b) Rosalind Franklin published about 40 scientific papers before her untimely death in 1958 at the age of 37.

Figure: 9-3 Title: The Watson-Crick model of DNA structure Caption: (a) Hydrogen bonding between complementary base pairs holds the two strands of DNA together. Three hydrogen bonds hold guanine to cytosine; two hydrogen bonds hold adenine to thymine. (b) Strands of DNA wind about each other in a double helix, like a twisted ladder, with the sugar-phosphate backbone forming the uprights and the complementary base pairs forming the rungs. (c) A space-filling model of DNA structure. Question Which are harder to break, A-T bonds or C-G bonds?

Figure: E9-1 Title: The discovery of DNA Caption: James Watson and Francis Crick with a model of DNA structure.

Structure of DNA Hydrogen Bonds Between Complementary Bases Hold the Two DNA Molecules Together The Order of Nucleotides in DNA Can Encode Vast Amounts of Information Copyright © 2005 Pearson Prentice Hall, Inc.

DNA Replication: The Process The Replication of DNA Is a Critical Event in a Cell’s Life DNA Replication Produces Two DNA Double Helices, Each with One Old Strand and One New Strand Basic features of DNA replication (F9.4 p. 155) DNA replication (F3 p. 158) Copyright © 2005 Pearson Prentice Hall, Inc.

free nucleotides Figure :9-4 Title: Basic features of DNA replication Caption: During replication, the two strands of the parental DNA double helix separate. Free nucleotides that are complementary to those in each strand are joined to make new daughter strands. Each parental strand and its new daughter strand then form a new double helix. free nucleotides

replication forks DNA helicase DNA helicase DNA polymerase #1 DNA replication bubble DNA polymerase #1 continuous synthesis discontinuous synthesis DNA polymerase #2 DNA polymerase #1 continues along parental DNA strand DNA polymerase #2 leaves continuous synthesis Figure: E9-2 Title: Details of DNA replication Caption: (a) DNA helicase separates the parental strands to form a replication bubble. (b) DNA polymerase synthesizes new pieces of DNA. (c) DNA helicase and DNA polymerase move along a replication bubble. (d) DNA ligase joins the small DNA segments into a single daughter strand. Question During synthesis, why doesn't DNA polymerase move away from the replication fork on both strands? discontinuous synthesis DNA polymerase #3 DNA polymerase #3 leaves DNA polymerase #4 DNA ligase joins daughter DNA strands

DNA replication Figure: 9-UN3 Title: DNA replication

DNA Replication: Accuracy Genetic Constancy During Cell Reproduction Proofreading: Produces Almost Error-Free Replication of DNA 1 Replication Error/ 1,000 to 10,000 BP Proofreading => 1 Error/1,000,000 BP Mistakes Do Happen Produces Variability Natural Selection Can Only Act on Variants that Exist Essential for Evolution Good for Population, Even if Bad for Individual Human Vs. HIV Copyright © 2005 Pearson Prentice Hall, Inc.