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Exploring DNA, RNA & Protein Synthesis: Structure, Replication, and Mutations

Discover the fascinating world of DNA, RNA, and protein synthesis. Learn about the structure of DNA, replication process, protein synthesis steps, and common mutations. Explore the significance of genetic code and impact of mutations on human health.

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Exploring DNA, RNA & Protein Synthesis: Structure, Replication, and Mutations

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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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