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DNA Review

DNA Review. The nucleotide bases will point to the inside of the DNA molecule while the outside (backbone) of the DNA molecule will be made of the sugar and phosphate molecules When complete the DNA molecule forms a double helix (two spiral sides wrapped together). CHROMOSOMES CONTAIN DNA.

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DNA Review

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  1. DNA Review • The nucleotide bases will point to the inside of the DNA molecule while the outside (backbone) of the DNA molecule will be made of the sugar and phosphate molecules • When complete the DNA molecule forms a double helix (two spiral sides wrapped together)

  2. CHROMOSOMES CONTAIN DNA • The nucleus contains chromatin • Chromatin is made of smaller nucleosomes • A nucleosome is formed by a DNA molecule wrapped around a protein “stick” • Looks like cotton candy wrapped around the paper cone

  3. Protein Synthesis

  4. Why is it important? • Cells are controlled by enzymes- enzymes are proteins • Almost every substance made by the cell is or contains a stuctural protein

  5. Vocabulary • Gene- a portion of DNA that codes for a protein- the “recipe” for a protein • mRNA- messenger RNA • tRNA- transfer RNA- transfers amino acids • Codon- mRNA’s complementary trio of bases • Anticodon- tRNA’s complementary trio of bases • Transcription- mRNA making a template of DNA’s code • Translation- tRNA “reading” mRNA’s code and transferring the amino acids necessary to form a protein

  6. Two Steps to Protein Synthesis • Transcription- takes place in the nucleus-mRNA makes template of DNA’s code • Translation- takes place on the ribosome in the cytoplasm- tRNA transfers amino acids

  7. Things to Remember • DNA contains the “recipes” for proteins- called genes • DNA is made of the bases adenine, thymine, guanine and cytosine • A-T and C-G • RNA is made of the bases adenine, uracil, guanine and cytosine • A-U and C-G

  8. Transcription • Takes place in the nucleus • DNA unzips • mRNA makes a template of the DNA code • mRNA copies the code three bases at a time- this is a codon

  9. Transcription- mRNA forms codons

  10. Translation- on the ribosome, tRNA transfers amino acids

  11. Another Look

  12. Another View

  13. Each codon codes for a specific amino acid The four bases can combine in 64 different triplicate (codon) combinations

  14. Codon Chart

  15. Another Codon Chart

  16. Protein Structure

  17. A Few of The Finished Products! Proteins

  18. Think About It- • Letters→ Words→ Sentences Sam hit the ball. • Bases→ Amino Acids→ Proteins

  19. View It! http://www.wisc-online.com/objects/index_tj.asp?objID=AP1302 http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html

  20. Wrap Up • 1. DNA message is transcribed into messenger RNA (mRNA) • 2. mRNA leaves the nucleus and attaches to a ribosome • 3. Each three letter codon will attract a matching three letter anti-codon of transfer RNA (tRNA) • 4. Each tRNA is carrying an amino acid “on its back” • 5. As the tRNA molecules line up, their amino acids also line up • 6. As the amino acids are lined up, they chemically bond to form a protein

  21. Mutations- Any error in the genetic code Can happen when: • DNA is making new copies of itself (replication) • DNA is being used to make messenger RNA (transcription) • Transfer RNA is being attracted to the messenger RNA at the ribosome (translation)

  22. Types of Mutations • Point mutations happen when one or two bases are different than they are supposed to be • Frameshift mutations happen when extra bases are added or deleted

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