Bodies Cells DNA. Bodies are made up of cells All cells run on a set of instructions spelled out in DNA

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1 What is DNA? Although the environment influences how an organism develops, the genetic information that is held in the molecules of DNA ultimately determines an organism s traits. DNA achieves its control by determining the structure of proteins. Within the structure of DNA is the information for life the complete instructions for manufacturing all the proteins for an organism.

2 Bodies Cells DNA Bodies are made up of cells All cells run on a set of instructions spelled out in DNA

3 The Transforming Principle 1928 Frederick Griffith Streptococcus pneumonia bacteria was working to find cure for pneumonia harmless live bacteria ( rough ) mixed with heat-killed pathogenic bacteria ( smooth ) causes fatal disease in mice a substance passed from dead bacteria to live bacteria to change their phenotype Transforming Principle

4 The Transforming Principle mix heat-killed pathogenic & live pathogenic live non-pathogenic heat-killed non-pathogenic strain of bacteria strain of bacteria pathogenic bacteria bacteria A. B. C. D. mice die mice live mice live mice die Transformation = change in phenotype something in heat-killed bacteria could still transmit disease-causing properties

5 DNA is the Transforming Principle Avery, McCarty & MacLeod purified both DNA & proteins separately from Streptococcus pneumonia bacteria which will change non-pathogenic bacteria? injected protein into bacteria no effect injected DNA into bacteria transformed harmless bacteria into virulent bacteria mice die 1944 What s the conclusion?

6 Confirmation of DNA Hershey Hershey & Chase Why use Sulfur vs. Phosphorus? classic blender experiment worked with bacteriophage viruses that infect bacteria grew phage viruses in 2 media, radioactively labeled with either 35 S in their proteins 32 P in their DNA infected bacteria with labeled phages

7 Hershey & Chase Protein coat labeled with 35 S T2 bacteriophages are labeled with radioactive isotopes S vs. P DNA labeled with 32 P bacteriophages infect bacterial cells Which radioactive marker is found inside the cell? bacterial cells are agitated to remove viral protein coats Which molecule carries viral genetic info? 35 S radioactivity found in the medium 32 P radioactivity found in the bacterial cells

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9 Blender experiment Radioactive phage & bacteria in blender 35 S phage radioactive proteins stayed in supernatant therefore viral protein did NOT enter bacteria 32 P phage radioactive DNA stayed in pellet therefore viral DNA did enter bacteria Confirmed DNA is transforming factor Taaa-Daaa!

10 Hershey & Chase Hershey Martha Chase & Alfred Hershey

11 The structure of nucleotides DNA is a polymer made of repeating subunits called nucleotides.(the monomer) Nucleotides have three parts: a simple sugar, a phosphate group, and a nitrogenous base. Phosphate group Nitrogenous base Sugar (deoxyribose)

12 The structure of nucleotides In DNA there are four possible nucleotides, each containing one of these four bases. The phosphate groups and deoxyribose molecules form the backbone of the chain, and the nitrogenous bases stick out like the teeth of a zipper. Nucleotide Phosphate group Nitrogenous base (A, G, C, or T) Thymine (T) Sugar (deoxyribose) Sugar-phosphate Website upload backbone 2015 DNA nucleotide

13 Chargaff DNA composition: Chargaff s rules varies from species to species all 4 bases not in equal quantity bases present in characteristic ratio humans: A = 30.9% T = 29.4% G = 19.9% C = 19.8% Rules A = T C = G 1947 That s interesting! What do you notice?

14 Paired bases DNA structure double helix 2 sides like a ladder Bases match together A pairs with T A : T C pairs with G C : G

15 Structure of DNA James Watson and Francis Crick worked out the threedimensional structure of DNA, based on work by Rosalind Franklin and Maurice Wilkins Wilkins

16 Rosalind Franklin ( )

17 DNA is a double-stranded helix Watson and Crick also proposed that DNA is shaped like a long zipper that is twisted into a coil like a spring. Because DNA is composed of two strands twisted together, its shape is called double helix.

18 The structure of DNA Base pair Hydrogen bond Ribbon model Partial chemical structure Computer model

19 Anti-parallel strands DNA molecule has direction complementary strand runs in opposite direction

20 The importance of nucleotide Chromosome sequences The sequence of nucleotides forms the unique genetic information of an organism. The closer the relationship is between two organisms, the more similar their DNA nucleotide sequences will be.

21 The importance of nucleotide Chromosome sequences Scientists use nucleotide sequences to determine evolutionary relationships among organisms, to determine whether two people are related, and to identify bodies of crime victims.

22 Organizing & packaging DNA DNA cell nucleus DNA in chromosomes in everyday working cell DNA has been wound up cell 4 chromosomes in this organism nucleus DNA in chromosomes in cell getting ready to divide

23 DNA Packing DNA double helix (2-nm diameter Histones Beads on a string Nucleosome (10-nm diameter) Tight helical fiber (30-nm diameter) Supercoil (200-nm diameter) 700 nm Metaphase chromosome

24 Nucleosomes Beads on a string 1 st level of DNA packing histone proteins 8 protein molecules positively charged amino acids bind tightly to negatively charged DNA 8 histone molecules