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Protein Synthesis

Unit Objectives (Chapter 12-3). By the end of this unit you will:know what transcription isknow what translation isunderstand how proteins are made. . Big picture. DNA contains the genetic code which controls the production of proteinsProteins, as we have learned, do everything!There are two im

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Protein Synthesis

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    2. Unit Objectives (Chapter 12-3) By the end of this unit you will: know what transcription is know what translation is understand how proteins are made.

    3. Big picture DNA contains the genetic code which controls the production of proteins Proteins, as we have learned, do everything! There are two important events which must happen in order to make a protein; transcription and translation

    4. Transcription Transcribing or copying the coded message of DNA onto a single stranded nucleic acid called mRNA DNAs code is contained in groups of 3 nitrogen bases called DNA triplets One side of DNA is considered the coding side, or template, and the other side is considered the complimentary side. Left side coding side Right side complimentary strand

    5. To begin transcription, Helicase causes the molecule to split or unzip. This exposes the nitrogen bases of the coding side Free floating mRNA nucleotides attach to the coding side of DNA The whole mRNA strand is removed from the coding side of DNA The mRNA strand then moves out of the nucleus and heads for a ribosome. The DNA strand then can re-attach with the complementary side of DNA

    7. Transcription

    8. mRNA Each group of 3 nitrogen bases of mRNA are called codons.

    9. Codon Wheel

    10. The Genetic Code

    11. Name the Amino Acids GGG? UCA? CAU? GCA? AAA?

    12. Our way:

    14. Summary Transcription is copying the DNA code onto a mRNA molecule. mRNA leaves the nucleus and moves to the ribosome where the message is translated AUG is called the Initiation Codon . It begins the process and always codes for Methionine Termination Codons indicate the end of the process. UAG,UAA, and UGA are termination codons and dont code for any amino acids

    15. Lets try Transcription: Draw a DNA molecule with the base sequence ATG GCA. Make the 5 on the top left. Assuming the coding side of DNA is the left side, transcribe a mRNA molecule. Draw the molecule horizontally. Remember how we do it!

    16. Look like this?

    17. Transcription Review DNA contains the genetic code for the production of __________. Each group of 3 nitrogen bases in DNA is called a __________. The genetic code of _____ is trapped inside the nucleus because it is ____________ to fit through the pores in the nuclear envelope. __________ is the process of copying the genetic code of _____ onto a single strand of _____. The single stranded _____ molecule falls on its side with its nitrogen bases pointing _____ and moves out of the nucleus to find a __________. Each group of 3 nitrogen bases in mRNA is called a __________. AUG is a special codon that is called an ________________. It always codes for the amino acid __________. Check you codon wheel and identify the amino acids that the following codons code for: GGC - __________ UUU - __________ CAU - __________ GUA - __________

    18. Transcription Review Another special codon found in mRNA stops the chain of amino acids and indicates the protein is complete. These codons are called ________________. There are only 3 of the codons: _______; ________ and _______. We are always going to assume that the coding side of DNA will be the __________ side. Opposite the coding side is called the __________ side. Two enzymes play a role in transcription: ____________ unzips the DNA molecule and __________________ helps attach the free-floating mRNA nucleotides to the coding side of DNA.

    19. Transcription Review DNA contains the genetic code for the production of Protein. Each group of 3 nitrogen bases in DNA is called a DNA triplet. The genetic code of DNA is trapped inside the nucleus because it is too big to fit through the pores in the nuclear envelope. Transcription is the process of copying the genetic code of DNA onto a single strand of mRNA. The single stranded mRNA molecule falls on its side with its nitrogen bases pointing up and moves out of the nucleus to find a ribosome. Each group of 3 nitrogen bases in mRNA is called a codon. AUG is a special codon that is called an Initiation codon. It always codes for the amino acid Methionine. Check you codon wheel and identify the amino acids that the following codons code for: GGC - Glycine UUU - Phenylalanine CAU - Histidine GUA - Valine

    20. Transcription Review Another special codon found in mRNA stops the chain of amino acids and indicates the protein is complete. These codons are called Termination codons. There are only 3 of the codons: UGA; UAA and UAG. We are always going to assume that the coding side of DNA will be the left side. Opposite the coding side is called the complimentary side. Two enzymes play a role in transcription: Helicase unzips the DNA molecule and RNA polymerase helps attach the free-floating mRNA nucleotides to the coding side of DNA.

    21. Transcription Review Look at the DNA molecule below. Beside the molecule, draw a horizontal mRNA molecule that would be transcribed from the coding left side. Bracket off your codons, and check your wheel to identify the amino acids the mRNA molecule would code for. Write the names of the amino acids above their respective codons.

    22. Translation The process where the message of mRNA is translated into sequences of amino acids. Translation happens on the surface of ribosomes. 3 codons can fit on the ribosome at one time. Remember tRNA?

    23. tRNA ? amino acid (specific to tRNA) ? tRNA molecule ? nitrogen bases called anticodons

    24. tRNA cont Each tRNA molecule with one specific anticodon sequence can carry only one specific amino acid. If the anticodon of tRNA is complimentary to the codon of mRNA the amino acid carried by that tRNA is dropped off. Protein Synthesis PH

    27. Translation Animations Translation Translation 2 Translation 3

    28. Activity Use your codon chart to complete the following table:

    29. A few things we need to know Gene A Gene B Exons translatable seqments of a chromosome Introns segments of DNA that do NOT code for proteins Nonsense DNA AUG intiation codon Codes for methionine UAA, UAG, and UGA are all termination codons

    30. Protein Synthesis

    31. Protein Synthesis Another look at Protein Synthesis

    32. Activity: Protein Synthesis Draw a DNA molecule with the following sequence on the left side (top to bottom) CAT ATA TGC CTA Transcribe a mRNA molecule using the coding side. Dettach it and draw it hortizontally (remember how we do it) Translate the message into amino acids (dont worry about drawing tRNA molecules) Using you amino acid chart, draw the reactants and products of this synthesis.

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