Presentation on theme: "DNA video project SOME BACKGROUND INFO…. WHAT IS THE “STUFF” OF HEREDITY? WHAT IS ITS STRUCTURE? The following scientists helped to answer these questions."— Presentation transcript:
WHAT IS THE “STUFF” OF HEREDITY? WHAT IS ITS STRUCTURE? The following scientists helped to answer these questions. GriffithAveryHershey-Chase Watson, Crick Wilkins and Franklin Chargaff
I. GRIFFITH’S EXPERIMENT 1928 A. - make a vaccine against harmful S. pneumoniae bacteria harmful S. pneumoniae bacteria 1. virulent S strain (S. pneumoniae) 1. virulent S strain (S. pneumoniae) a. virulent means disease causing a. virulent means disease causing b. capsule around the bacteria b. capsule around the bacteria provides protection from body provides protection from body defenses defenses 2. non virulent R strain (no capsule) 2. non virulent R strain (no capsule) a. destroyed by body(can not cause a. destroyed by body(can not cause disease) disease)
B. PROCEDURE and RESULTS 1. mouse injected with R cells 2. mouse injected with S cells 3. mouse injected with heat killed S cells 4. mouse injected with killed S cells mixed with live R cells mouse lives mouse dies mouse lives mouse dies
C. C - Heat-killed S bacteria release hereditary material that makes R strain bacteria virulent HOW??? HOW??? 1.Principle of Transformation 1.Principle of Transformation a. transfer of genetic material (DNA) from one organism to another a. transfer of genetic material (DNA) from one organism to another b. DNA for making a capsule was transferred from the S strain to the b. DNA for making a capsule was transferred from the S strain to the R strain making it virulent R strain making it virulent
II. AVERY’S EXPERIMENTS (early 1940’s) A – Is the transforming agent protein, RNA or DNA? B. PROCEDURE – (Three Experiments) 1. destroy 3 different molecules in the 1. destroy 3 different molecules in the heat-killed S strain bacteria and mix heat-killed S strain bacteria and mix with R strain bacteria with R strain bacteria a. destroy protein (protease enzyme) a. destroy protein (protease enzyme) b. destroy RNA (RNase enzyme) b. destroy RNA (RNase enzyme) c. destroy DNA (DNase enzyme) c. destroy DNA (DNase enzyme)
C. Results 1. Missing protein a. transforms R cells to S cells a. transforms R cells to S cells (mouse dies) (mouse dies) 2. Missing RNA a. transforms R cells to S cells) a. transforms R cells to S cells) (mouse dies) (mouse dies) 3. Missing DNA a. did not transform R cells to S cells a. did not transform R cells to S cells (mouse lives) (mouse lives)
Oswald Avery Oswald Avery D. Conclusion – DNA is responsible for the transforming principle the transforming principle
III. HERSHEY-CHASE EXPERIMENT 1952 (Martha Chase and Alfred Hershey) – Is the hereditary material in viruses protein or DNA? B. PROCEDURE 1. Label protein and DNA in a phage with radioactive isotopes (S-35 and P-32) 1. Label protein and DNA in a phage with radioactive isotopes (S-35 and P-32) a. a phage is a virus that attacks a. a phage is a virus that attacks bacteria bacteria b. S-35 labels protein and P-32 b. S-35 labels protein and P-32 labels DNA labels DNA
Martha Chase and Alfred Hershey used Phage Viruses for Their Experiment
B. Procedure 2. Allow protein-labeled and DNA- 2. Allow protein-labeled and DNA- labeled phage (virus) to infect E. coli labeled phage (virus) to infect E. coli bacteria bacteria 3. remove and separate phage (virus) 3. remove and separate phage (virus) from the bacteria (E. coli ) from the bacteria (E. coli )
Hershey-Chase Experiment - all viral DNA and a small amount of protein entered the bacteria D. CONCLUSION - DNA is the hereditary molecule in viruses
IV. Watson and Crick (1953) /Wilkins and Franklin A. Watson and Crick 1. double helix model of DNA based on the 1. double helix model of DNA based on the work of other scientists work of other scientists B. Maurice Wilkins and Rosalind Franklin 1. x-ray diffraction photographs of DNA 1. x-ray diffraction photographs of DNA helped Watson and Crick develop their helped Watson and Crick develop their model model 2. Watson, Crick and Wilkins received 2. Watson, Crick and Wilkins received Nobel Prize in l962 (Franklin died in 1958 Nobel Prize in l962 (Franklin died in 1958 and could not be named for the award) and could not be named for the award)
X-ray Diffraction Photo Rosalind Franklin of DNA) and Maurice Wilkens
V. Erwin Chargaff - 1949 A. Percent of nitrogen bases that pair with each other (complementary bases) is the same 1. percent adenine equals percent thymine 1. percent adenine equals percent thymine percent guanine equals percent cytosine percent guanine equals percent cytosine 2. implied base pairing rules 2. implied base pairing rules
Questions you should be able to answer… 1)Where is DNA located in the cell? 2)How is it arranged? 3)What is the purpose of DNA? What does it do???? 4)How many strands does it have and what does it generally look like? 5)What is the basic building block of DNA called and what three components make it up? 6)What are the complimentary base pairs of DNA?
Chromosome - DNA Chromosome-Chromatid Where is it located in the cell? NUCLEUS! How is it arranged? Purpose? To code for everything in your body...genetic blueprint!
DNA Structure 1. Deoxyribonucleic acid is shaped like a twisted ladder (double helix)
2.DNA is a polymer made up of monomers called nucleotides Each nucleotide consists of: a. a sugar called deoxyribose b. a phosphate c. 1 of 4 nitrogen bases (A, G, T, C) DNA Structure
Purine and pyrimidine adenine nitrogen bases (purine)= thymine nitrogen bases (pyrimidine) guanine nitrogen bases (purine)= the cytosine nitrogen bases (pyrimidine) DNA Structure
Erwin Chargaff: discovered complementary base pair rules the # of adenine nitrogen bases = the # of thymine nitrogen bases the # of guanine nitrogen bases = the # of cytosine nitrogen bases DNA Structure
A = T G= C DNA carries the genetic code in its sequence of bases
What is the complementary sequence of the bases listed below? A T T G C A A G C T C T G C
3.The sides of the DNA helix are held up by phosphates and sugars (deoxyribose) Hydrogen bonds: hold complimentary bases together; very weak and can be easily broken DNA Structure
DNA Replication Build a DNA molecule http://learn.genetics.utah.edu/conte nt/begin/dna/builddna/ http://learn.genetics.utah.edu/conte nt/begin/dna/builddna/
WE ALSO HAVE RNA in our bodies A. RNA contains 1. sugar molecule - ribose 1. sugar molecule - ribose 2. phosphate 2. phosphate 3. nitrogen bases 3. nitrogen bases a. adenine and guanine a. adenine and guanine b. cytosine and uracil b. cytosine and uracil B. The three types of RNA are: a) messenger RNA (m-RNA) a) messenger RNA (m-RNA) b) transfer RNA (t-RNA) b) transfer RNA (t-RNA) c) ribosomal RNA (r-RNA) c) ribosomal RNA (r-RNA)
Differences between DNA -RNA DNA RNA Deoxyribose Ribose Double strand Single strand Thyamine Uracil
GENES ARE SEGMENTS OF DNA THAT CODE FOR A CHARACTERISTIC, LIKE DIMPLES. REALLY ITS THE ORDER OF THE BASES IN THE DNA DETERMINE THE CHARACTERISTIC. BUT SOMETIMES PROBLEMS ARISE….
Mutations A. Location of Mutations 1. somatic cell (body cell) 1. somatic cell (body cell) 2. germ cell (cells that form sperm 2. germ cell (cells that form sperm and egg cells) and egg cells) B. Causes 1. radiation 1. radiation a. x-rays, alpha, beta, gamma a. x-rays, alpha, beta, gamma radiation, u.v. light radiation, u.v. light 2. chemicals (mutagens) 2. chemicals (mutagens) 3. DNA sequence changes in replication 3. DNA sequence changes in replication
C. Effects of Mutations 1. lethal (deadly) 1. lethal (deadly) 2. may be beneficial 2. may be beneficial 3. no effect 3. no effect
Point Mutation change in one nucleotide …or change in a base (A,T,C,G) in the DNA molecule Types of mutations – a. substitution – one base is substituted for another b. addition or insertion – an extra base is added c. removal or deletion of a base
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