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Structure of DNA

Structure of DNA. An overview. DNA contains the blueprints or codebook for life Stores information for protein production Proteins direct cellular activity and determine characteristics. Located in the nucleus of eukaryotes. Made up of units called nucleotides

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Structure of DNA

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  1. Structure of DNA An overview

  2. DNA contains the blueprints or codebook for life • Stores information for protein production • Proteins direct cellular activity and determine characteristics

  3. Located in the nucleus of eukaryotes

  4. Made up of units called nucleotides • Consists of deoxyribose, phosphate groups, and N carrying base • Bases are guanine (G), Cytosine (C), Adenine (A), Thymine (T)

  5. Shape is called a double helix • Outside is made of alternating phosphates and sugar groups • Inside is made of N carrying bases

  6. Base-paring rule: structure and size of each of the Nitrogen bases only allows the following pairing • A pairs with T • C pairs with G • Bases of one strand of DNA are complimentary to the other

  7. Sequence of Nucleotides is the code that controls the production of all proteins

  8. DNA REVIEW

  9. The order: DNA  transcription  RNA  translation  protein

  10. Copying DNA Replication- the process of DNA copying itself • takes 6 -8 hours • is done BEFORE mitosis or meiosis

  11. DNA is unzipped by special enzymes called DNA Helicases • break the H bonds between the strand

  12. replication fork =areas on either end of the DNA where the double helix is separated • occurs in a circle, not one end to another)

  13. Once the DNA is partially unzipped, special enzymes called DNA Polymerases move along the exposed DNA making a complimentary strand for it.

  14. Enzymes stay bonded to the DNA until all of the DNA is copied • Once the copying is done, you have 2 identical strands of DNA

  15. Polymerases are able to double check their work • Typically few errors • Approximately 1 per billion nucleotides

  16. DNA’s instructions are carried out by RNA (ribonucleic acid) • Acts as photocopier, copying genes • Contains more H than DNA does • Made of G, C, A and U (Uracil) instead of T • Is a SINGLE STRANDED molecule

  17. Transcription – transfer of instructions for making a protein from a gene to RNA • Done in nucleus • Similar to copying DNA • RNA polymerase binds to a gene’s promoter (AUG sequence) • Unzips the DNA • Reads and copies the DNA using RNA base pairs (substitute U for T) • Reaches a stop signal and the RNA is released

  18. Translation – translates RNA base sequence into the Amino acid sequence of a protein • done in Ribosomes • begins at the UAG code • uses mRNA (messenger) to carry the code from the nucleus to the ribosome • uses tRNA (transfer) to pick up the amino acid in the cytoplasm and carries it to the ribosome • uses rRNA (ribosomal) to bind mRNA and tRNA

  19. The order: DNA  transcription  RNA  translation  protein

  20. RNA REVIEW

  21. DNA / RNA comparison

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