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Protein Synthesis

Protein Synthesis. Review What is RNA and Why is it Important? Types of RNA C odons & Anticodons Transcription Translation Amino Acids and The Codon Chart. Review. Review. Remember how the bases bond in DNA? DNA: A T G C T T A G

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Protein Synthesis

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  1. Protein Synthesis Review What is RNA and Why is it Important? Types of RNA Codons & Anticodons Transcription Translation Amino Acids and The Codon Chart

  2. Review

  3. Review Remember how the bases bond in DNA? DNA: AT G C T T A G RNA is rearranged in a similar complimentary form: DNA: A T G C T T A G RNA: T A C G A A T C U A C G A A U C

  4. Protein Synthesis • Protein Synthesis is the process of making proteins from a DNA template • But wait a minute- • Where is DNA? • Where are proteins made? • How do we get proteins from DNA if the DNA can’t leave? • We make RNA from the DNA template! • Why is RNA important? • It uses the code from DNA to make amino acids • Amino acids combine to make proteins In the nucleus The Ribosome

  5. What is a protein? • Polypeptide • Made from amino acids linked together • The amino acids are held together with covalent peptide bonds • The amino acids are linked together in a long chain called a polypeptide. • The polypeptide chain twists up into a complex shape called a protein.

  6. Amino Acids • There are 20 different amino acids • Combining 3 different RNA nitrogen pairs creates 1 amino acid • Example: UAC = Tyrosine (1 amino acid) AAU = Asparginine ( 1 amino acid) GUU = Valine (1 amino acid) • Combining 3 or more amino acids creates 1 protein • Example: Tyrosine + Asparginine + Valine = 1 Protien!

  7. Amino Acids • The order of the amino acids determine the protein’s shape • The protein’s shape determines its function. • If the protein has the wrong shape, it won’t work right!!!!! • So it’s really, really important that the amino acids get put in the right order

  8. Protein Synthesis • Before we learn the process of protein synthesis, we need to learn the places: • Places: • Nucleus • Has the DNA template • Cytoplasm • The fluid within the cell • Amino acids are floating within • Ribosome • Organelle where amino acids are put together • Putting together amino acids = making a protein

  9. Protein Synthesis • Before we learn the process of protein synthesis, we need to learn the parts: • Parts: • rRNA = ribosomal RNA • Helps make-up the ribosome (rRNA is 80% of the ribosome) • aids in bonding mRNA to tRNA • mRNA = messanger RNA • Created in the nucleus, travels through the cytoplasm to the ribosome • Carries “the message” • Codon(more on this later) • tRNA = transfer RNA • Moves amino acids from the cytoplasm to the ribosome • Anticodon (more on this later)

  10. Nucleus DNA mRNA E Cytoplasm New Protein tRNA E E Ribosome Amino Acids E The Cell

  11. Protein Synthesis • Two step process • Transcription • Happens in the nucleus with mRNA • Translation • Happens in the cytoplasm and ribosome with the mRNA, tRNA and amino acids

  12. Protein Synthesis • Part One: Transcription • Segments of DNA are separated by RNA polymerase • One of the detached strands is used as the template to make mRNA • RNA polymerase adds mRNA nucleotides to the exposed DNA strand • This creates mRNA

  13. Protein Synthesis Transcription- Let’s Practice! (remember, in RNA T’s become U’s) DNA = A G C T T A mRNA = (codon) *Codon: every combination of three nitrogen bases or the “letters” (3 nucleotides = 1 codon = 1 amino acid) U C G A A U Codon Codon

  14. Codon Question • A piece of mRNA is made of 15 nucleotides (bases) • How many codons does it have? • A piece of mRNA is made of 30 nucleotides (bases) • How many codons does it have? • A piece of mRNA is made of 60 nucleotides (bases) • How many codons does it have?

  15. Protein Synthesis • Part Two: Translation • The newly formed mRNA leaves the nucleus and attaches to a ribosome • The mRNA “translates” the DNA code to the tRNA that is waiting in the cytoplasm. • Basically, the codon that mRNA has needs to be paired with the tRNAanticodon

  16. Protein Synthesis • Part Two: Translation continued… • The tRNA has a specific amino acid attached to it • The tRNAanticodon carrying the amino acid attaches to the mRNA codon Practice: DNA: A T G C A T mRNA: (codon) tRNA: (anticodon) U A C G U A A U G C A U AntiCodon AntiCodon

  17. Translation Continued • Once two amino acids are present at the ribosome, a peptide bond forms that hold the amino acids together • Multiple amino acids bonded together = a protein

  18. The process of matching tRNA to mRNA continues until all mRNA codons are matched to their anticodons OR once a “stop” codon is read. - The end result is a polypeptide (a protein)

  19. Amino Acids • If I were to give you a strand of DNA, you should be able to tell me: • The complimentary mRNA strand (codon) • The amino acid the mRNA is coding for • The tRNA strand (anticodon) that brings the amino acid to the ribosome • To determine the amino acid the mRNA is coding for, you can use an mRNA codon table

  20. If mRNA is UCG Find U for the first base C for the second base And G for the third base -UCG codes for Serine - The anticodon AGC brings Serine to the ribosome

  21. DNA: G A C T T A mRNA: (codon) Use the codon chart on the next slide to determine the amino acid it codes for C U G A A U

  22. CUG= AAU =

  23. What is the mRNA strand? C U G A A U DNA: G A C T T A mRNA: (codon) Amino Acids: What must the tRNA be to attach those amino acids? tRNA: (anticodon) What amino acids does the mRNA code for? Leucine Asparagine G A C U U A

  24. Mutations • Thinking about the mutations we saw in Chromosomes…. • If we were suppose to have the sequence: GGU- CCA-UGA- UUC But a deletion mutation occurred and eliminated all of the GUANINE bases, what would the altered sequence look like? • Deletion mutation for CYTOSINE? • What would happen to the protein being made? • UCC-AUA-UUC • GGU-AUG-AUU

  25. Codon Question • A piece of mRNA is made of 15 nucleotides (bases) • How many codons does it have? • How many anticodons does it have? • How many amino acids will the protein have? • A piece of mRNA is made of 30 nucleotides (bases) • How many codons does it have? • How many anticodons does it have? • How many amino acids will the protein have? • A piece of mRNA is made of 60 nucleotides (bases) • How many codons does it have? • How many anticodons does it have? • How many amino acids will the protein have?

  26. Review • The DNA code AAA-CTG- CAA is in the nucleus • During transcription, the mRNA strand UUU-GAC- GUU is made • The mRNA strand leaves the nucleus and attaches to the ribosome • During translation, the mRNA codon tells tRNA it needs the amino acids Phenylalanine, Aspartic acid and Valine out in the cytoplasm • tRNA finds Phenylalanine, Aspartic acid and Valine in the cytoplasm, and being the anticodon, attaches to mRNA • Phenylalanine , Aspartic acid and Valine are held together by peptide bonds and create a polypeptide (or a protein)

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