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Ch. 9 &10

Ch. 9 &10. DNA, RNA & Protein Synthesis. I. DNA-Deoxyribonucleic Acid. A. In 1953 James Watson and Francis Crick built a model of DNA based on x-rays taken by Rosalind Franklin. B. DNA Structure 1. Shape- Double Helix (winding staircase)

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Ch. 9 &10

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  1. Ch. 9 &10 DNA, RNA & Protein Synthesis

  2. I. DNA-Deoxyribonucleic Acid A. In 1953 James Watson and Francis Crick built a model of DNA based on x-rays taken by Rosalind Franklin

  3. B. DNA Structure 1. Shape- Double Helix (winding staircase) 2. Made of Repeating Nucleotides: 3 parts a) Phosphate group b) Deoxyribose Sugar c) Nitrogen base

  4. C. Nitrogen Bases- 2 types 1. Purines- 2 carbon rings in structure, Adenine & Guanine 2. Pyrimidines- 1 carbon ring in structure, Thymine & Cytosine

  5. D. A Purine is always paired with a pyrimidine, held together by weak H bonds A=T G C 2 stars 3 stars E. Bases are always attached to deoxyribose sugars

  6. DNA drawing Right-hand rule= nitrogen bases only bond on R side-results in 2 opposite running strands P S P S P S P S P S P S -A -C -G = = = -C -G -T http://www.ted.com/talks/james_watson_on_how_he_discovered_dna.html

  7. QUIZ • Name the people who made the first model of DNA. • What are the 4 nitrogen bases (words not letters)? • What are the three parts that make up a nucleotide? • What is DNA’s shape? • Which bases are pyrimidines? • Which are doubled-ringed, purines or pyrimidines? • What type of bonds hold the nitrogen bases together in the middle of the DNA strand? • How many bonds form between A and T? • How many bonds form between G and C? • Why is a DNA molecule said to be complementary? • What is the complementary strand of DNA for ACATGG?

  8. Answers-18 pts total • 2-Watson and Crick • 4-Adenine, Guanine, Cytosine, Thymine • 3-Phosphate, Sugar, Base • 1-Double helix/winding staircase • 2-Thymine, cytosine • 1-Purines • 1- Hydrogen Bonds • 1- 2 hydrogen bonds • 1- 3 hydrogen bonds • 1- by knowing the nitrogen bases on one side of the DNA we can determine the sequence of bases for the other side of the DNA • 1-TGTACC

  9. II. DNA Replication • Replication- the process of copying DNA to get ready for cell division, occurs in the nucleus • Steps • Helix unwinds and an enzyme (DNA helicase) breaks the Hydrogen bonds between the bases

  10. Enzyme (DNA Polymerase) moves along each strand and adds the complementary base to each ½ strand; Polymerase also proofreads its work

  11. 3. Strands Detach and 2 new identical strands are formed

  12. 4. Process is considered a semi-conservative process because the strands are ½ original, ½ new DNA

  13. III. Protein Synthesis A. The process of producing proteins made of amino acids from the instructions provided by the DNA

  14. B. RNA-(ribonucleic Acid) gets instructions to ribosome to make proteins • Single Strand • Ribose instead of Deoxyribose Sugar • No Thymine, Uracil replaces Thymine • 3 Types of RNA

  15. a) Messenger RNA- (mRNA)- copy of information from DNA - every 3 nitrogen bases make a codon, these code for a specific amino acid

  16. Transfer RNA- (tRNA)- transports amino acids, has a matching anti-codon -3 nitrogen bases make an anticodon

  17. c) Ribosomal RNA- (rRNA)- makes up ribosomes

  18. ***2 steps for Protein Synthesis C. Transcription-unwinds DNA and makes a copy called mRNA, occurs in the nucleus

  19. D. Translation- mRNA and tRNA build a protein out of amino acids. Occurs in the cytoplasm at a ribosome

  20. Animations • http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf • http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf

  21. IV. Mutations- a change in the DNA of a gene, occurs during replication 3 types: 1. Substitution- one nucleotide is replaced with a different nucleotide 2. Insertion- one or more nucleotides are added 3. Deletion- one or more nucleotides are deleted

  22. Humans inherit 3 billion base pairs of DNA from each parent. That means that each cell has 6 billion pairs that can be a target of a mutation. It is estimated that mutations occur in about 1 in every 50 million nucleotides. That means that each new cell could have some 120 mutations Mutations can: -have no effect (occur in the “junk DNA”, about 97% of DNA does not encode for anything- that we know of) -be silent-mutations that code for the same amino acid -cause disease such as Cystic Fibrosis, Retinoblastoma, Sickle Cell anemia -occur in gametes (egg & sperm)- can result in Fragile X syndrome and Huntington’s disease

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