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Updated February 2006 Created by C. Ippolito April 2005 Chapter 12 DNA and RNA 12-1 DNA pp. 287-294 12-2 Chromosomes and DNA Replication pp. 295-299 12-3.

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Presentation on theme: "Updated February 2006 Created by C. Ippolito April 2005 Chapter 12 DNA and RNA 12-1 DNA pp. 287-294 12-2 Chromosomes and DNA Replication pp. 295-299 12-3."— Presentation transcript:

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2 Updated February 2006 Created by C. Ippolito April 2005 Chapter 12 DNA and RNA 12-1 DNA pp Chromosomes and DNA Replication pp RNA and Protein Synthesis pp Mutations pp

3 Updated February 2006 Created by C. Ippolito April 2005 Chapter 12 Section 1 DNA Objectives: Summarize the relationship between genes and DNA. Describe the overall structure of the DNA molecule.

4 Updated February 2006 Created by C. Ippolito April 2005 Griffith and Transformation Studied bacteria that cause pneumonia Studied bacteria that cause pneumonia –Smooth (S) Form – cause pneumonia –Rough (R) Form – does not cause pneumonia

5 Updated February 2006 Created by C. Ippolito April 2005 Griffith Experiments

6 Updated February 2006 Created by C. Ippolito April 2005 Transformation Heat killed S-form bacteria passed their disease causing ability to harmless R-form bacteria Heat killed S-form bacteria passed their disease causing ability to harmless R-form bacteria –R-form bacteria became S-form bacteria and reproduced as S-form bacteria

7 Updated February 2006 Created by C. Ippolito April 2005 Avery and DNA Oswald Avery at Rockefeller University Oswald Avery at Rockefeller University –separated each chemical from heat killed S- form bacteria –injected each component with live R-form –ONLY DNA caused TRANSFORMATION –DNA may transmit genetic information

8 Updated February 2006 Created by C. Ippolito April 2005 Bacteriophage Virus that attacks bacteria Virus that attacks bacteria Virus – “nonliving” Virus – “nonliving” –Outer protein coat –Inner DNA or RNA

9 Updated February 2006 Created by C. Ippolito April 2005 Hershey Chase Experiment Used radioisotopes (tracers) P 32 and S 35 Used radioisotopes (tracers) P 32 and S 35

10 Updated February 2006 Created by C. Ippolito April 2005 The Structure of DNA DNA is composed of nucleotides DNA is composed of nucleotides Each DNA nucleotide has: Each DNA nucleotide has: –Sugar – deoxyribose –Phosphate Group –Nitrogen Base  Purines – double ring – adenine & guanine  Pyrimidines – single ring – thymine & cytosine

11 Updated February 2006 Created by C. Ippolito April 2005 DNA Nucleotides Chargaff’s Rule Chargaff’s Rule –% of guanine always equals amount of cytosine –% of adenine always equals amount of thymine –G = C –A = T

12 Updated February 2006 Created by C. Ippolito April 2005 X-Ray Evidence Rosalind Franklin Rosalind Franklin –used x-ray crystallography to photograph DNA –Photograph 51 used by Watson and Crick to build model –Visit these links to find out more about Miss Franklin and her photo ess_photo51_globeandmail.html ess_photo51_globeandmail.html ess_photo51_globeandmail.html

13 Updated February 2006 Created by C. Ippolito April 2005 Watson and Crick Model Shape is a “twisted ladder” or Double Helix Shape is a “twisted ladder” or Double Helix –Sides - sugar and phosphates –Steps – nitrogen base pairs  adenine and thymine OR guanine and cytosine –Link for interactive tutorial:  lmb.cam.ac.uk/DNA/index. html lmb.cam.ac.uk/DNA/index. html lmb.cam.ac.uk/DNA/index. html  To use site download Chime Plug-In from mr- ippolito-science-class.org mr- ippolito-science-class.orgmr- ippolito-science-class.org

14 Updated February 2006 Created by C. Ippolito April 2005 Chapter 12 Section 2 Chromosomes and DNA Replication Objectives: Summarize the events of DNA replication. Relate the DNA molecule to chromosome structure.

15 Updated February 2006 Created by C. Ippolito April 2005 DNA and Chromosomes Chromosomes are made of DNA & Proteins Chromosomes are made of DNA & Proteins –DNA is wrapped around the protein histone –Nucleosomes are groups of histones

16 Updated February 2006 Created by C. Ippolito April 2005 DNA Replication DNA makes a copy of itself before cell division DNA makes a copy of itself before cell division 1.DNA separates into two strands 2.Each strand acts as a template 3.Complementary strands formed by base pairing 4.Catalyzed by the enzyme DNA polymerase visit these links:

17 Updated February 2006 Created by C. Ippolito April 2005 DNA Unzips 4a special enzyme opens the double helix 4It does this by breaking the weak hydrogen bonds between bases 4The enzyme slowly proceeds down the middle of the DNA molecule 4until the DNA molecule is completed opened 4This will allow exposed bases to be matched forming new “sides”

18 Updated February 2006 Created by C. Ippolito April 2005 DNA Polymerase 3Nucleotides from cell storage area are brought in by enzymes 3The enzyme positions them opposite the proper base to form new base pairs 3new hydrogen bonds form between the bases 3Resulting in two identical strands of DNA 3Each strand is half new and half old DNA

19 Updated February 2006 Created by C. Ippolito April 2005 Chapter 12 Section 3 RNA and Protein Synthesis Objectives: Tell how RNA differs from DNA. Name the THREE (3) main types of RNA. Describe transcription and the editing of RNA. Identify the genetic code. Summarize translation. Explain the relationship between genes and proteins.

20 Updated February 2006 Created by C. Ippolito April 2005 Structure of RNA Each RNA nucleotide has: Each RNA nucleotide has: –Sugar –ribose –Phosphate Group –Nitrogen Base  Purines – double ring – adenine & guanine  Pyrimidines – single ring – uracil & cytosine

21 Updated February 2006 Created by C. Ippolito April 2005 Types of RNA Three kinds of RNA Three kinds of RNA –Messenger RNA (mRNA) – carries instructions to ribosome –Transfer RNA (tRNA) – carries amino acids to ribosome –Ribosomal RNA (rRNA) – forms part of the ribosome

22 Updated February 2006 Created by C. Ippolito April 2005 Transcription DNA copies its nucleotide sequence into RNA DNA copies its nucleotide sequence into RNA 1.RNA polymerase binds to DNA promoter region. 2.DNA separates into two strands. 3.RNA polymerase uses one DNA strand as a template. 4.Complimentary bases match template to form RNA. 5.RNA leaves and DNA closes

23 Updated February 2006 Created by C. Ippolito April 2005 RNA Editing Introns – parts of DNA that form pre-edited RNA that are cut out of the mRNA Introns – parts of DNA that form pre-edited RNA that are cut out of the mRNA Exons – parts of DNA that form parts of pre- edited RNA that are spliced together to make mRNA. Exons – parts of DNA that form parts of pre- edited RNA that are spliced together to make mRNA.

24 Updated February 2006 Created by C. Ippolito April 2005 Genetic Code Nitrogen base sequence “names” amino acids of a protein Nitrogen base sequence “names” amino acids of a protein –20 different amino acids –4 bases A C G U –3 bases names an amino acid (codon)

25 Updated February 2006 Created by C. Ippolito April 2005 Translation mRNA decoded at ribosome to form proteins mRNA decoded at ribosome to form proteins 1.mRNA attaches to ribosome 2.tRNA anticodon matches mRNA codons 3.Amino acids on tRNA’s bond together 4.Ribosome moves to next repeating process 5.At end mRNA, protein and ribosome released Visit: Lew-Port’s Biology Place - Protein Synthesis Animation Visit: Lew-Port’s Biology Place - Protein Synthesis Animation Lew-Port’s Biology Place - Protein Synthesis Animation Lew-Port’s Biology Place - Protein Synthesis Animation –Biostudio Protein Synthesis Animation Biostudio Protein Synthesis AnimationBiostudio Protein Synthesis Animation

26 Updated February 2006 Created by C. Ippolito April 2005 Chapter 12 Section 4 Mutations Objectives: Contrast gene mutations and chromosome mutations.

27 Updated February 2006 Created by C. Ippolito April 2005 Mutations Changes in DNA that affect an individual’s genetic information Changes in DNA that affect an individual’s genetic information –Gene Mutation – affects a single gene –Chromosome Mutation – affects whole or parts of chromosomes

28 Updated February 2006 Created by C. Ippolito April 2005 Gene Mutations Point Mutation Point Mutation –changes one nucleotide in DNA

29 Updated February 2006 Created by C. Ippolito April 2005 Chromosomal Mutations


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