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DNA

DNA. The Code of Life. Topics Covered. The DNA Molecule DNA Replication How DNA works Transcription Translation. DNA. Deoxyribonucleic acid Discovered by Watson and Crick Made up of nucleotides Double helix 2 coiled strands (twisted ladder) Strands are complimentary. Nucleotide.

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DNA

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  1. DNA The Code of Life

  2. Topics Covered • The DNA Molecule • DNA Replication • How DNA works • Transcription • Translation

  3. DNA • Deoxyribonucleic acid • Discovered by Watson and Crick • Made up of nucleotides • Double helix • 2 coiled strands (twisted ladder) • Strands are complimentary

  4. Nucleotide THREE PARTS • Sugar • Deoxyribose (in DNA) • Ribose (in RNA) • Phosphate group • Nitrogen Base NB S P

  5. G C • Guanine (G) A • Cytosine (C) T • Adenine (A) • Thymine (T) The Four Nucleotides PURINES PYRIMIDINES

  6. C T A A T G Two Complimentary Strands BASE PAIRING (Chargaff’s Rule) • A – T or T – A • G – C or C - G G C

  7. The Double Helix

  8. DNA Replication • Why does DNA need to replicate (copy) itself? • MITOSIS • Replication preserves the sequence of bases in an organism’s DNA

  9. T A C G A T T A A A T G C T A A T T T A C G A T T A A A T G C T A A T T DNA Replication: Step 1 • The DNA molecule unzips

  10. T A C G A T T A A A T A T G C T A A T T T A G C C G T A A T T A T T A A Replication: Steps 2 & 3 • DNA polymerase adds the correct complimentary nucleotide to each exposed strand • A complimentary strand is created for each original strand

  11. DNA, Genes & Chromosomes • Chromosomes • long strands of DNA • How many chromosomes do humans have? • Genes • part of a chromosome • Each gene codes for a different protein

  12. Proteins • Gene Expression • The use of genetic material to make a protein • Protein ultimately determines a trait • Amino Acids • Building blocks of proteins

  13. How does DNA code for a protein? • Nucleotide bases “spell out” the message • ORDER is important • OIGLOBY • BIOLOGY • DNA alphabet has 4 letter • G A T C

  14. transcription translation RNA Protein Protein Synthesis • Transcription • An RNA copy of DNA is made • Translation • RNA is translated in to a protein DNA

  15. C A G RNA • Ribonucleic acid • Messenger for DNA • Single stranded • No thymine (T) has uracil (U) instead U

  16. Transcription • An RNA copy of DNA is made • Called mRNA • Only one side of DNA is copied • Occurs in the Nucleus • Once mRNA is made it leaves the nucleus (through a pore)

  17. T A C G A T T A A A T G C T A A T T T A C G A T T A A A T G C T A A T T TRC: Step 1 • The DNA molecule unzips

  18. T A C G A T T A A A T G C T A A T T TRC: Step 2 • RNA polymerase binds to one strand of DNA at the promoter site

  19. T A C G A T T A A A T G C T A A T T G U A A U U TRC: Step 3 A • RNA pol. Pairs each nucleotide base with its complimentary base • One strand Only!! U C

  20. TRC: Step 4 • New messenger RNA (mRNA) leaves the nucleus through a nuclear pore nucleus cytoplasm A U G C U A A U U

  21. Translation • RNA translated into a protein • Two types of RNA work together • mRNA – messenger • tRNA – transfer • Occurs in the cytoplasm • Genetic Code is the translator • Each “word” is 3 letters • GCA = alanine (see genetic code)

  22. Genetic Code • CODON • three letter “word” in mRNA • Specify a particular amino acid • ANTICODON • Three leter “word” in tRNA • Complimentary to the codon

  23. The Genetic Code

  24. TRL: Step 1 • mRNA “start” codon binds to a ribosome • AUG = start • AUG = methionine ribosome A U G C U A A U U

  25. met met U A C U A C A U G C U A A U U TRL: Steps 2 & 3 • tRNA picks up an amino acid in the cytoplasm and carries to ribosome • tRNA anticodon binds to complimentary mRNA codon

  26. met met U A C U A C A U G C U A A U U TRL: Steps 4 & 5 • Amino acid detaches from the tRNA and attaches to a growing protein chain • tRNA leaves to find another amino acid

  27. met met leu met leu leu leu G A U G A U G A U G A U A U G C U A A U U A U G C U A A U U TRL: Step 6 • Continues as mRNA passes through ribosome and one tRNA after another is selected to match the mRNA codons

  28. met leu A U G C U A A U U TRL: Step 7 • Ends when a “stop” codon is reached and the newly assembled protein is released into the cell stop

  29. G C C C A T T T A A G G

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