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Protein Synthesis Pages 336-341

Protein Synthesis Pages 336-341. Part 3. Warm-Up: DNA 101. DNA is a double stranded sequence of ___________ (smallest unit of DNA). Short segments of DNA are called _______ which code for the manufacture of ___________ (a macromolecule).

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Protein Synthesis Pages 336-341

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  1. Protein SynthesisPages 336-341 Part 3

  2. Warm-Up: DNA 101 • DNA is a double stranded sequence of ___________ (smallest unit of DNA). • Short segments of DNA are called _______ which code for the manufacture of ___________ (a macromolecule). • DNA is stored in the _________ of a cell (control center of the cell). • The DNA code must be transmitted to the organelles in the cytoplasm where proteins are built called the __________.

  3. Essential Questions • What is the primary function of DNA? • Compare and contrast DNA and RNA. • What are the three types of RNA? Describe their function. • How do the base-pairing rules for RNA compare to the rules for DNA? • Describe the roles of DNA and RNA in the overall process of protein synthesis.

  4. What two nucleic acids can be found in cells? 1. DNA = deoxyribonucleic acid 2. RNA = ribonucleic acid

  5. The role of DNA is to store and transmit genetic information.

  6. But DNA can’t leave the nucleus! • This is where RNA comes in. RNA carries the genetic code from the nucleus to the ribosomes in the cytoplasm so the ribosomes can make the proteins that genes in the DNA code for.

  7. How do DNA & RNA compare? RNA • Ribose sugar & phosphate “backbone” • Nitrogen base, URACILreplaces thymine in RNA • Single-stranded DNA • Deoxyribose sugar & phosphate “backbone” • N-bases: A, C, G, T • Double helix

  8. 5. Involves Uracil Single-stranded Double-stranded Check your understanding…Decide whether the following describes DNA or RNA: • Blueprint copy • Stays in nucleus • Goes to ribosome • Involves Thymine

  9. Types of RNA: 1. Messenger RNA (mRNA) Genes of DNA are transcribed into mRNA. mRNA carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm.

  10. Types of RNA 2. Ribosomal RNA (rRNA) Ribosomes are made up of a combination of RNA and proteins. The RNA that makes up ribosomes is called rRNA.

  11. Types of RNA 3. Transfer RNA (tRNA) Transfers amino acids to ribosomes so the ribosomes can assemble them into proteins.

  12. Nucleotides in DNA vs. RNA RNA Adenine Uracil Cytosine Guanine DNA Adenine Thymine Cytosine Guanine

  13. PROTEIN SYNTHESIS Stage 1: Transcription Stage 2: Translation

  14. Stage 1: TRANSCRIPTION • From DNA, a strand of mRNA is manufactured. Why? Because DNA can’t leave the nucleus but mRNA can! • The DNA double helix is unzipped so that the nucleotides are exposed. • One of the DNA strands is used as a template strand for the synthesis of RNA. http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf

  15. TRANSCRIPTION • The bonds that hold A-T and C-G in DNA are hydrogen bonds which are weak bonds. Enzymes unzip the DNA double helix. • RNA polymerase assembles mRNA nucleotides from the DNA template but the base pairing rules for RNA are slightly different: • Wherever there’s an adenine on the DNA template, RNA polymerase puts a uracil to make the mRNA strand. • Wherever there’s a cytosine on the DNA template, a guanine will be added to make the mRNA • T-A • G-C

  16. Step 1: Helicaseenzyme “unzips” double helix by weakening H-bonds A T G T T T G A A A C T U A C A A A C U U U G A mRNA - - A - - T - - G - - T - - T - - T - - G - - A - - A - - A - - C - - T T - - A - - C - - A - - A - - A - - C - - T - - T - - T - - G - - A - - DNA Write the complementary codon sequence. Slide  Copy the following DNA sequence. Write the complementary nucleotide sequence. Step 2: RNA polymerase enzyme forms complementary mRNA strand

  17. Stage 2: TRANSLATION • The genetic code carried from the DNA by the mRNA is translated to make protein strands. • Occurs in the cytoplasm on a ribosome.

  18. TRANSLATION • mRNA travels to aribosome where each codon is read. • The codons on mRNA match an anticodon on tRNAwhich carries a specific amino acid. • When the codon and anticodon match, the amino acid being carried by the tRNA is transferred to a growing protein chain on the ribosome. http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120077/micro06.swf::Protein%20Synthesis

  19. Let’s use your foldable from before. U A C A A A C U U U G A mRNA A T G T T T G A A A C T DNA  Open the foldable and translate the mRNA code into the correct amino acid sequence.

  20. The translation… A T G T T T G A A A C T DNA U A C A A A C U U U G A mRNA Tyrosine Lysine Leucine STOP

  21. Central Dogma of Biology DNA codes for RNA, which guides the synthesis of proteins. DNA  RNA  Protein • DNA is unzipped • RNA polymerase uses DNA as a template for making mRNA (Uracil is incorporated instead of thymine) • mRNA moves out of nucleus to ribosome • tRNA carries amino acids to ribosome where they are assembled into a peptide chain • Upon reading a STOP codon, the complete protein chain is released

  22. Now consider this… • On a sheet of paper, write the word CATS. • Try rearranging the letters to form as many 3-letter words as you can. • Write each word on your paper, and then add a definition for each word. • Did any of the codes you formed have the same meaning?

  23. The DNA Alphabet • Like CATS, there are only 4 nitrogen bases in the DNA alphabet. • Like the CATS activity, DNA “words” are only 3-letters. These triplet base sequences are called codons.

  24. BRAIN TEASER How many codons can be made using the four letters of the four different bases? Hint: • A codon is made up of 3 nucleotides. • So there are 3 spots and a possibility of 4 bases in each. 4 bases x 4 bases x 4 bases = 64 possible codon combinations. Since the nitrogen base is the only unit to change, the sequence of bases makes up the code.

  25. How is DNA like Morse code?

  26. How is DNA like Morse code? It is a series of single repeating units (sounds or symbols) that make up a message. The repeating units are the nucleotides of the DNA molecule. The message is the final protein that is produced. Proteins can be structural, enzymatic, hormones, etc.

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