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DNA (Deoxyribonucleic Acid)

Understand the process of protein synthesis from DNA to amino acids, using transcription and translation, crucial for creating life. Explore the Central Dogma, codons, tRNA, and ribosomes. Test your knowledge with the information provided.

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DNA (Deoxyribonucleic Acid)

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  1. DNA(Deoxyribonucleic Acid) • What is it? • Read Chap 13 • How does it work? • Read Chap 14 • How do we know? • Read 13, 14 & class notes

  2. The Central DogmaDNA makes PROTEINS and PROTEINS make LIFE

  3. The Central DogmaDNA makes PROTEINS and PROTEINS make LIFE • But how? • At its essence, DNA is a set of instructions for making proteins. • “DNA is a cookbook and the genes are recipes” • Proteins are made from different arrangements of protein building blocks called Amino Acids. • There are 20 different Amino Acids. You get them from your food.

  4. So how do you change the protein in a tuna fish sandwich into human hemoglobin, hair, enzymes, etc.???

  5. There’s a little problem here…

  6. Step 1: TranscriptionCopying the DNADNAg mRNA

  7. Transcription: Copying the DNADNAgmRNA

  8. Transcription: Copying the DNADNAgmRNACOMPARISON OF DNA AND MESSENGER RNA

  9. Transcription: Copying the DNADNAgmRNACOMPARISON OF DNA AND MESSENGER RNA

  10. How can 4 bases tell you how to make proteins from 20 amino acids??? • Law of Parsimony (The simplest answer is often the right answer. Sort of, not always but a lot.) • 4 letter alphabet making 1–letter words? • 4-letter alphabet making 2-letter words?

  11. mRNA & Codons The 3-base units of information on mRNA are called codons. AAU,GCC,CAU,GGG,CGA……………. Codons “spell out” the names of the specific amino acids to be used in making a specific PROTEIN. The sequence of bases on DNA or RNA is called, duh, the “base sequence”

  12. The Universal Genetic Code is 64 tripletsIt’s a 4-letter alphabet that makes 64 3-letter words

  13. Protein Synthesis (makin’ proteins)So this movie requires another actor… TRANSFER RNA (tRNA)

  14. Transfer RNA (tRNA)

  15. Protein Synthesis • Some terms that you MUST know… • DNA codes or triplets (the genetic code of DNA) • TRANSCRIPTION (of DNA to make mRNA) • mRNA CODONS (3-base information units of mRNA • tRNAANTICODONS (anticodons pair with codons) • TRANSLATION (tRNA reads mRNA to make a protein)

  16. OK, so you want to make some protein…

  17. Hook together AMINO ACIDS with PEPTIDE BONDS

  18. Protein Synthesis = Translation(makin’ proteins)

  19. Codons

  20. Transfer RNA (tRNA)“Picks up and transfers the amino acids over to the ribosome and mRNA”

  21. tRNA Structure codon in mRNA anticodon in tRNA amino acid Fig. 14-7, p.223

  22. Protein Synthesis (makin’ proteins)

  23. “Poly-ribosomes”

  24. Transcription Overview rRNA tRNA mRNA Mature mRNA transcripts ribosomal subunits mature tRNA Translation

  25. elongation binding site for mRNA P (first binding site for tRNA) A (second binding site for tRNA) Amino Acid 1 Amino Acid 1 Amino Acid 2 c Initiation ends when a large and small ribosomal subunit converge and bind together. Amino Acid 2 d The initiator tRNA binds to the ribosome. e One of the rRNA molecules b Initiation, the first stage of translating mRNA, will start when an initiator tRNA binds to a small ribosomal subunit. initiation a A mature mRNA transcript leaves the nucleus through a pore in the nuclear envelope. Fig. 14-9a-e, p.224

  26. g A third tRNA binds with the next codon f The first tRNA is released h Steps f and g are repeated termination i A STOP codon moves into the area where the chain is being built. j The new polypeptide chain is released from the ribosome. k The two ribosomal subunits now separate, also. Fig. 14-9f-k, p.224

  27. and all this requires just 28 molecules…

  28. THE END. TEST NEXT TIME.

  29. Extra slides below. Disregard the remaining slides…

  30. Hershey and Chase

  31. REPLICATION OF DNA

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