3/10/16 DNA. Essential Question. Answer in your journal notebook/ What impact does DNA play in agriculture, science, and society as a whole?

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1 DNA Essential Question. Answer in your journal notebook/ What impact does DNA play in agriculture, science, and society as a whole? 1

2 Benchmark SC.912.N.1.3, SC912.L16.9 Explain how & why the genetic code is universal & common to all organisms EOC Study Items: 1. Describe a bacteriophage. 2. Identify and describe the structure & function of DNA. 3. Explain the basic process of DNA replication 4. Explain the basic process of transcription & translation 5. Types of genetic mutations 6. mrna codon chart Pg 244 WARM-UP 2

3 Why are proteins important? 1. Proteins make up the structural components of a cell 2. Direct most of the cells chemical activity 3. Body movement 4. Defense against germs (antibodies) 5. Biochemical reactions (enzymes) DNA (Deoxyribonucleic Acid) 3

4 Friedrich Miescher 1869 Swiss physician Discovered DNA Studied pusridden bandages Isolated nuclei called nuclein Montage showing (from left to right) Friedrich Miescher, Tübingen castle, a vial containing DNA isolated by Miescher, his original publication describing his discovery of DNA and his laboratory in Tübingen castle. A HISTORY OF DNA SEE p Discovery of the DNA double helix A. Frederick Griffith Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928) B. Rosalind Franklin - X-ray photo of DNA. (1952) C. Watson and Crick - described the DNA s structure molecule from Franklin s X-ray. (1953) 4

5 Fredrick Griffith microbiologist was investigating two forms of the bacterium that causes pneumonia. What material changed harmless R bacteria into diseasecausing S bacteria? Griffith called this mystery material the transforming principle. Alfred Hershey and Martha Chase American biologists Studied viruses that infect bacteria called bacteriophage Takes over a bacterium s genetic machinery and directs it to make more viruses. DNA molecule surrounded by a protein coat 5

6 DNA molecule surrounded by a protein coat Bacteriophage Experiment concluded that the phages DNA had entered the bacteria, but the protein had not. Hersey-Chase Experiment 6

7 Genetic material of cells GENES units of genetic material that CODES FOR A SPECIFIC TRAIT Called NUCLEIC ACIDS (DNA/RNA) DNA is made up of repeating molecules called NUCLEOTIDES (monomer) DNA Nucleotide (3 Parts) Phosphate Group O O=P-O O CH2 C 4 Sugar (deoxyribose) 5 O C 3 C 2 C 1 N Nitrogenous base (A, G, C, or T) Single or double rings 7

8 Watson & Crick proposed DNA had specific pairing between the 4 nitrogen bases: ADENINE THYMINE CYTOSINE - GUANINE DNA was made of 2 long stands of nucleotides arranged in a specific way called the Complementary Rule DNA Double Helix Rungs of ladder Nitrogenous Base (A,T,G or C) Legs of ladder Phosphate & Sugar Backbone 8

9 5 O DNA Double Helix 3 P 3 O 5 P strong 5 4 O 1 G C P 5 3 O 2 T A 1 O 3 5 P P 3 weak O 5 P Nitrogenous Bases PURINES 1. Adenine (A) 2. Guanine (G) PYRIMIDINES 3. Thymine (T) A or G 4. Cytosine (C) T or C 9

10 Chargaff s Rule Adenine must pair with Thymine Guanine must pair with Cytosine Their amounts in a given DNA molecule will be about the same. T A G C BASE-PAIRINGS H-bonds G C T A 10

11 Genetic Diversity Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms. The Code of Life The code of the chromosome is the SPECIFIC ORDER that bases occur. A T C G T A T G C G G 11

12 DNA is wrapped tightly around histones and coiled tightly to form chromosomes LET S REVIEW DNA 1. List the conclusions Griffith & Avery, Hershey & Chase drew from their experiments. 2. Summarize the relationship between genes & DNA. 3. Describe the overall structure of the DNA molecule. 4. What are the 4 kinds of bases? 12

13 LET S REVIEW DNA 1. List the conclusions Griffith & Avery, Hershey & Chase drew from their experiments. Genetic material is made of DNA 2. Summarize the relationship between genes & DNA. Genes are segments on DNA 3. Describe the overall structure of the DNA molecule. Stores genetic information, Double helix, 2 spirals or DNA strands twisted, phosphate group, sugar, nitrogen bases 4. What are the 4 kinds of bases? ADENINE THYMINE CYTOSINE - GUANINE What is DNA? 13

14 DNA Replication DNA must be copied The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing: A-T, G-C Each strand of the original DNA serves as a template for the new strand See p. 235 Interesting fact! 14

15 DNA Replication Semiconservative Model: 1. Watson and Crick showed: the two strands of the parental molecule separate, and each functions as a template for synthesis of a new complementary strand.. Parental DNA DNA Template New DNA Replication Quiz 1. Why is replication necessary? A---? G---? 2. When does replication occur? C---? T---? 3. Describe how replication works. A---? G---? 4. Use the complementary rule to A---? create the complementary strand: G---? C---? A---? G---? T---? 15

16 Replication Quiz 1. Why is replication necessary? So both new cells will have the correct DNA 2. When does replication occur? During interphase (S phase). 3. Describe how replication works. Enzymes unzip DNA and complementary nucleotides join each original strand. 4. Use the complementary rule to create the complementary strand: A---T G---C C---G T---A A---T G---C A---T G---C C---G A---T G---C T---A (1961) Watson & Crick proposed DNA controlled cell function by serving as a template for PROTEIN structure. 3 Nucleotides = a triplet or CODON (which code for a specific AMINO ACID) See p.303 AMINO ACIDS are the building blocks of proteins. 16

17 DNA Transcription DNA can unzip itself and RNA nucleotides match up to the DNA strand. See p.301 Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids. AMAZING DNA FACTS DNA from a single human cell extends in a single thread for almost 2 meters long!!! It contains information equal to some 600,000 printed pages of 500 words each!!! (a library of about 1,000 books) 17

18 DNA Translation The cell uses information from messenger RNA to produce proteins See p We will discuss details of this on a later date Transcription/Translation Quiz 1. Why is transcription necessary? 2. Describe transcription. 3. Why is translation necessary? 4. Describe translation. 5. What are the main differences between DNA and RNA. 6. Using the chart on page 303, identify the amino acids coded for by these codons: UGGCAGUGC 18

19 1. Why is transcription necessary? Transcription makes messenger RNA (MRNA) to carry the code for proteins out of the nucleus to the ribosomes in the cytoplasm. 2. Describe transcription. RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble MRNA. 3. Why is translation necessary? Translation assures that the right amino acids are joined together by peptides to form the correct protein. 4. Describe translation. The cell uses information from MRNA to produce proteins. 5. What are the main differences between DNA and RNA. DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil. 6. Using the chart on page 303, identify the amino acids coded for by these codons: UGGCAGUGC tryptophan-glutamine-cysteine 19