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Warm up

Warm up. Write the complementary strand: 5’ T G A C A G C T T C 3’. Warm up. Write the complementary strand: 5’ T G A C A G C T T C 3’ 3’ A C T G T C G A A G 5’. Review. DNA is made of subunits called nucleotides

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Warm up

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  1. Warm up Write the complementary strand: 5’ T G A C A G C T T C 3’

  2. Warm up Write the complementary strand: 5’ T G A C A G C T T C 3’ 3’ A C T G T C G A A G 5’

  3. Review • DNA is made of subunits called nucleotides • DNA nucleotides are composed of a phosphate, deoxyribosesugar, and a nitrogen-containing base • The 4 bases in DNA are: adenine (A), thymine (T),guanine (G), and cytosine (C) • Located in the nucleus of the cell

  4. Replication • Occurs when chromosomes duplicate and make exact copies of the DNA • Hydrogen bonds between bases are broken by helicase to “unzip” the molecule • Each old strand of nucleotides serves as a template for each new strand • New nucleotides move into complementary positions are joined by DNA polymerase

  5. Chapter 10 : DNA, RNA and Protein Synthesis Ms. Mezzetti Lynn English High School Science Department Modified version from Kim Useglia-former student teacher @ Lynn English

  6. Thought: • If DNA is in the nucleus and enzymes and amino acid building blocks for proteins are in the cytosol how do the messages get sent through the cell?

  7. DNA RNA Protein The Central Dogma

  8. RNA differs from DNA 1. RNA has a sugar ribose DNA has a sugar deoxyribose 2. RNA contains the base uracil (U) DNA has thymine (T) 3. RNA molecule is single-stranded DNA is double-stranded

  9. Types of RNA • Messenger RNA (mRNA) carries genetic information to the ribosomes in the cytosol • Ribosomal RNA (rRNA), along with protein, makes up the ribosomes • Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized

  10. Genes and Proteins • Proteins are made of amino acids linked together by peptide bonds • 20 different amino acids exist • Amino acids chains are called polypeptides • Segment of DNA that codes for the amino acid sequence in a protein are called genes

  11. Steps of Protein Synthesis • Transcription makes an RNA molecule complementary to a portion of DNA • Translationoccurs when the sequence of bases of mRNA DIRECTS the sequence of amino acids in a polypeptide

  12. Transcription DNARNA

  13. Transcription 1) DNA unwinds and serves as a template for mRNA synthesis 2) RNA polymerase reads DNA and adds RNA nucleotides

  14. Messenger RNA • Carries the information for a specific protein • Made up of 500 to 1000 nucleotides long • Single stranded

  15. Practice: What would be the complementary RNA strand to following DNA sequence? 5’ G A T C G A T C A A C 3’

  16. Practice: What would be the complementary RNA strand to following DNA sequence? 5’ G A T C G A T C A A C 3’ 3’ C U A G C U A G U U G 5’

  17. Genetic Code • DNA contains a triplet code, Sequence of 3 bases called codon • Codes for amino acids • Every three bases on DNA stands for ONE amino acid • Each three-letter unit on mRNA is called a codon

  18. Practice: DNA 5’ G A T C G A T C A A C G 3’ RNA 3’ C U A G C U A G U U G C 5’

  19. Practice: DNA 5’ G A T C G A T C A A C G 3’ RNA 3’ C U A G C U A G U U G C 5’ CODONS: CUA GCU AGU UGC

  20. Amino Acids • There are 20 amino acids with a possible 64 different triplets • Most amino acids have more than one codon! • The code is nearly universal among living organisms

  21. Genetic Code

  22. Genetic Wheel

  23. Important Codons • AUG – methionine or start codon • UAA, UAG, or UGA – stop codons

  24. Practice: • GGG • UCA • CAU • GCA • AAA

  25. Practice: • GGG • Glycine • UCA • Tyrosine • CAU • Histodine • GCA • Alanine • AAA • Lysine

  26. Translation RNA Protein

  27. Translation • Translation is the process of decoding the mRNA into a polypeptide chain

  28. Translation • Synthesis of proteins in the cytoplasm • Involves the following: 1. mRNA (codons) 2. tRNA (anticodons) 3. ribosomes 4. amino acids

  29. Transfer RNA (tRNA) • Made up of 75 to 80 nucleotideslong • Transports amino acidsto the mRNA • Have anticodons that are complementary to mRNA codons • Recognizes the appropriate codons on the mRNA and bonds to them with H-bonds

  30. amino acid attachment site U A C anticodon tRNA

  31. Ribosomes • Ribosomes read mRNA three bases or 1 codon (ex: GAC)at a time and construct the proteins • Made up of rRNA and proteins

  32. Ribosomal RNA (rRNA) • Made up of rRNA is 100 to 3000 nucleotideslong • Made inside the nucleus of a cell • Associates with proteins to form ribosomes

  33. How the protein is made Click to view Nova Protein Synthesis Video

  34. Proteins • The end products of protein synthesis is a primary structure of a protein • A sequence of amino acid bonded together by peptide bonds

  35. Protein Synthesis

  36. Review DNA mRNA tRNA (ribosomes) Protein

  37. Wrap up • Where does transcription take place? • What is the role of mRNA? • What is translation? Where does it take place? • What is a codon? Anticodon? • What is the role of tRNA? Ribosomes? • How does the protein get made? • Where does the protein go? What is it used for? Any questions?

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