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Presentation on theme: "FINDING DNA."— Presentation transcript:


2 Proof of DNA as Genetic Material
Was the genetic material protein or DNA? Mendel (peas) and Morgan (flies) did not know it was DNA. Worksheet links Bozeman Biology: DNA and RNA Part I Bozeman Biology: DNA and RNA Part II

3 Frederick Griffith A medical officer was trying to find a vaccine against pneumococcus

4 Rough and Smooth Pneumococcus

5 Griffith 1920’s Streptococcus pneumoniae used to show a “transforming factor”

6 Griffith’s Conclusion
Some material in the heat-killed S strain that was responsible for “transforming” the R-strain into a lethal form transformation = passing the inheritance factor from one organism to another THIS TRANSFORMING FACTOR WAS LATER FOUND TO BE DNA

7 Oswald Avery 1944 He had reported that DNA, not protein (which was believed at the time), was the hereditary substance (transforming material). Studied medical research

8 Oswald Avery 1940’s

9 Avery’s Conclusion Removed DNA, RNA, protein from S-strain pneumococcus AVERY PROVED THAT DNA WAS THE TRANSFORMING MATERIAL

10 Alfred Hershey and Margaret Chase 1953
Showed that the hereditary material in bacteriophage viruses is DNA. DNA in water

11 Hershey-Chase

12 Radioactive S35 in protein
Hershey-Chase Bacteriophages Youtube McGraw-Hill Hershey-Chase Experiment Radioactive P32 in DNA Radioactive S35 in protein

13 Hershey-Chase CONCLUSION – DNA is genetic material because (32P) nucleic acid not (35S) protein guides viral replication

14 Bacteriophages (“bacteria-eaters”)
Mostly made of just protein coat and DNA

15 Virus Examples HIV Virus Cold Virus Bird Flu Virus Ebola Virus

16 Herpes Virus

17 Bacteriophage Structure

18 Virus: Are they Alive? Viruses can only replicate in a living host.
"Viruses straddle the definition of life. They lie somewhere between supra molecular complexes and very simple biological entities. Viruses contain some of the structures and exhibit some of the activities that are common to organic life, but they are missing many of the others.” Dr. Mark Young of MSU youtube (4:00)

19 Bacteriophage Lytic Infection
Attach to host 2. Insert DNA 3. Make and assemble DNA parts 4. Lyse (burst) EXAMPLES: Cold Flu

20 Lysogenic Infection BIOL 230 Lecture Guide - Lysogenic Life Cycle of a Temperate Bacteriophage (animation link) 1. Virus lands on host. 2. Virus injects DNA into host. 3. Virus DNA attaches to host DNA = prophage. 4. Virus Prophage will become lytic when conditions are favorable (you are sick, tired).


22 Lysogenic Cycle Animation
Animation Quiz 2 - Lamda Phage Replication Cycle EXAMPLES: HERPES HIV CHICKEN POX

23 Click on “Journey into DNA”
NOVA Online | Cracking the Code of Life | Journey into DNA (keep clicking on “zoom” + button) View for extra credit Write 10 things you learned about DNA

24 What is the structure of DNA?
It is a nucleic acid Polynucleotide = Made of long chains of Nucleotides

25 DNA Nucleotide O O=P-O N CH2 O C1 C4 C3 C2 Phosphate Group
Nitrogenous base (A, G, C, or T) CH2 O C1 C4 C3 C2 5 Sugar (deoxyribose)


27 A Nucleotide MADE OF: Sugar Phosphate (A) (G) (T) (C) Base
Deoxyribose sugar PO4 4 kinds: (A) (G) (T) (C) (names on next slide)

28 4 Types of Base Pairs A = adenine T = thymine C = cytosine G = guanine NOW SING THE DNA SONG

29 Nitrogenous Bases PURINES -2 rings 1. Adenine (A) 2. Guanine (G)
PYRIMIDINES -1 ring 3. Thymine (T) 4. Cytosine (C) A or G T or C

30 Deoxyribonucleic Acid
DNA Deoxyribonucleic Acid (Get out colored pencils)

31 DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G or C)
“Legs of ladder” Phosphate & Sugar Backbone

32 DNA backbone Sugar Phosphate

33 DNA Structure Rungs of the Ladder: Backbone: Various orders of
A, T, C, G Backbone: Sugar and phosphates Alternate

34 DNA Double Helix P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A

35  National DNA Day, April 25, 2009 DNA SONG AND VIDEO

36 What’s RNA? Ribonucleic Acid Three types: mRNA tRNA rRNA

37 DNA RNA Comparing DNA and RNA Double stranded Sugar = deoxyribose
Bases: A-T, C-G Found only in nucleus Can repair itself RNA Single stranded Sugar = ribose Bases: A-U, C-G Found in and out of the nucleus Cannot repair itself


39 Pretty Similar Uracil Thymine

40 DNA RNA Both Single stranded molecule Contains uracil
Contains ribose sugar - Found in nucleus and cytoplasm Made of nucleotides - Contain adenine, guanine and cytosine Contains Thymine Contains deoxyribose sugar Double stranded molecule - Found only in nucleus

41 Bozeman Biology DNA and RNA Part 1
Griffith, Avery, Hershey and Chase, Watson and Crick, pro and eukaryotic chromos Bozeman Biology DNA and RNA part 2 DNA replication Transformation Protein synthesis

42 Relative Proportions (%) of Bases in DNA Organisms A T G C
Human Chicken Grasshopper   Sea Urchin Wheat Yeast E. coli

43 Question: If there is 30% Adenine, how much Cytosine is present?
HINT: A –T and C - G

44 Answer: There would be 20% Cytosine. Adenine (30%) = Thymine (30%)
Guanine (20%) = Cytosine (20%) Total of 100%

45 Chargaff’s Rules the amount of (A)denine will always equal the amount of (T)hymine And the amount of (G)uanine will always equal the amount of (C)ytosine. HOT!!!

46 Nitrogenous Bases Why does A bond only with T and C only with G?
What do you notice?

47 Nitrogenous Bases T and C are single-ring Pyrimidines
A and G are double-ring Purines A single bonds with a double

48 2 chains of nucleotides bind to form a DNA molecule
Hydrogen bonds form between the nitrogenous bases to join the 2 chains together The sugar and phosphate group together is known as the sugar-phosphate backbone

Helicase = separates 2 DNA strands (breaks H bonds) Primase=RNA primers at INITIATION

50 Topoisomerase = unwinding DNA
REPLICATION ENZYMES Topoisomerase = unwinding DNA DNA Polymerase = Adding of DNA nucleotides ELONGATION (proofread and repair)

LIGASE= Binds the Okazaki fragments Watch the enzymes in DNA Replication Animation

52 AT and C-G Base Pairing DNA Replication simple version) (link)
Media Showcase (cool animation link) Detailed Replication Link


54 in tons of combinations makes our genetic code
DNA STRUCTURE A-T C-G in tons of combinations makes our genetic code

55 DNA Replication Animation click here
Hi!...Still Awake? DNA Replication Animation click here

56 What is the complementary base sequence on the other strand of the DNA?

57 The Race is On! To Determine the Structure of the DNA molecule.

58 DNA Geek Rosalind Franklin was an English chemist who was working in an X-ray crystallography lab in Paris, France in 1951. FAMOUS PHOTO 51 (correct orientation of DNA)

59 Linus Pauling American biochemist suggested helix (spiral)shape
Most famous for Vitamin C prevents colds

60 DNA Geek Linus Pauling was a Caltech chemist (USA), who in 1951 had discovered the alpha helical nature of protein structure. I remember his books: Vitamin C and the Common Cold and Cancer and Vitamin C also The Nature of the Chemical Bond and protested nuclear testing

61 DNA Geeks James Watson, a biologist from Indiana University, and Francis Crick, a physicist, were working at the Cavendish Lab in Cambridge, England Nobel Prize for structure of DNA




65 Watson and Crick’s Wire Model
DOUBLE HELIX First put the nitrogenous bases on the outside

66 DNA Geek

67 DNA Base Pairs Adenine with Thymine Guanine with Cytosine

68 X ray Diffraction

69 Franklin’s Suggestion

70 DNA Bases










80 Beadle and Tatum


82 Happy DNA DAY The day commemorates the completion of the Human Genome Project in April 2003, and the discovery of DNA's double helix. DNA Song NOVA | Ghost in Your Genes | PBS

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