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DNA

DNA. What is DNA?. D eoxyribo n ucleic A cid DNA, the molecule that holds genetic information, makes an exact copy of itself whenever a cell divides. DNA stores the instructions for protein synthesis and is contained in chromosomes. Basic Structure of DNA. Deoxyribose. 5-Carbon Sugar

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DNA

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  1. DNA

  2. What is DNA? • Deoxyribonucleic Acid • DNA, the molecule that holds genetic information, makes an exact copy of itself whenever a cell divides. • DNA stores the instructions for protein synthesis and is contained in chromosomes

  3. Basic Structure of DNA

  4. Deoxyribose • 5-Carbon Sugar • Makes up part of the backbone of DNA

  5. Basic Structure of DNA

  6. Phosphate Group • Makes up other part of the backbone of DNA

  7. Basic Structure of DNA

  8. DNA Sugar-Phosphate Backbone • DNA Backbone • Double Helix-2 strands • Made up of the sugar and phosphate group

  9. Basic Structure of DNA

  10. Nitrogenous Base • Four kinds on nitrogenous bases: • Thymine (T) • Adenine (A) • Cytosine (C) • Guanine (G) • Held together by a hydrogen bond

  11. Chargaff’s Rules • Rules of Base Pairing: • A and T always go together • C and G always go together

  12. Basic Structure of DNA

  13. Nucleotides • Unit made of: • 5-carbon sugar • Phosphate Group • Nitrogenous Base

  14. Review

  15. How does DNA form a Chromosome?

  16. 3 Main steps in chromosome formation • Step 1: Replication • Pulls apart (1 double  2 single) original strand • Step 2: Transcription • Copies of an original single strand to formation of new strand • Step 3: Translation • Creation of final strand

  17. Step 1: DNA Replication • Because of the Double Helix design and base-pairing, each strand has all the information needed to reconstruct the other half. • Before a cell divides, it duplicates its DNA-called replication • During replication, the DNA separates into 2 strands which can then reconstruct a new strand.

  18. Unzipping • Unzips in hundreds of places. • Each spot of unzipping forms a “fork” • Hydrogen bonds are broken by an enzyme • DNA Polymerase-enzymethat helps in replication of DNA- “Proofreads”

  19. Why RNA & DNA? • DNA is the coded instructions for making protein. • RNA actually does the job of decoding the DNA’s instructions and then makes protein.

  20. Transcription/Translation Video

  21. RNA Structure • Like DNA-it’s long chain of nucleotides has: • 5-Carbon sugar • Phosphate group • Nitrogenous base • Unlike DNA, RNA has: • A different sugar: ribonucleic acid • Only one strand (sugar-phosphate backbone) • Has Uracil in place of Thymine

  22. RNA Structure • It’s a disposable copy of a segment of DNA. • It’s a working copy of a single gene. • The DNA sequence makes it possible for a single gene to produce hundreds or thousands of RNA molecules.

  23. Step 2: Transcription • Process of copying part of the DNA nucleotide sequence to make mRNA. • RNA Polymerase binds to the DNA and separates the strands. • Then, RNA Polymerase copies the strand of template DNA and assembles a strand of mRNA. • Template DNA: Strand that is being copied • First type: mRNA: Opposite copy of template DNA to make future copies

  24. Transcription • Notice in the mRNA (messenger RNA: to be copied) strand, all Thymine become Uracil

  25. Transcription Check-up • In your notes, write down this DNA sequence and transcribe it into mRNA: • A • C • T • G • G • C • A • T • C • A U G A C C G U A G U

  26. Step 3: Translation Transcription Complete! Next:

  27. Step 3: Translation • Translation is protein synthesis (make the final strand) • Uses mRNA to make proteins inside the rRNA. • rRNA: Ribosomal RNA • Occurs in the cytoplasm.

  28. Types of RNA • Second type of RNA: • 1. Ribosomal RNA -This is where proteins are assembled. -Like a factory ** Called Translation

  29. Types of RNA • Third type of RNA: • 3. Transfer RNA -Transfers amino acids to the ribosome where proteins are made.

  30. Transfer RNA

  31. tRNA • Anti-Codon (tRNA) -Matches with the codon (mRNA) to deliver the amino acid that makes the protein Codon Anti- Codon Protein Chain Amino Acid

  32. Genetic Code • Is the language of mRNA instructions. • Every 3 nucleotides of mRNA is a codon. • UCU- GCA- AUG- CAU • Each codon “Codes” for an amino acid. • A chain of amino acids make a protein

  33. Step 3: Translation • Starts (AUG) and stops with a “start” or “stop” codon. (like a sentence) • When a “stop” codon is reached, the protein is complete.

  34. What is that codon? • HISTIDINE • STOP • START OR METHIONINE • GLYCINE • ALANINE • ASPARAGINE • ARGININE • STOP • PROLINE • VALINE • CAU • UAG • AUG • GGU • GCU • AAC • CGU • UGA • CCG • GUU

  35. In Conclusion Genes contain nothing more than directions for assembling proteins. • Fun Video

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