1 PROTEIN SYNTHESIS CHAPTER 10 section 4

2 Starting with DNA DNA ‘s code must be copied and taken to the cytoplasmDNA ‘s code must be copied and taken to the cytoplasm In the cytoplasm, this code must be read so amino acids can be assembled to make polypeptides (proteins)In the cytoplasm, this code must be read so amino acids can be assembled to make polypeptides (proteins) This process is called PROTEIN SYNTHESISThis process is called PROTEIN SYNTHESIS

3 RNA Differs from DNA RNA has a sugar riboseRNA has a sugar ribose DNA has a sugar deoxyribose RNA contains the base uracil (U)RNA contains the base uracil (U) DNA has thymine (T) RNA molecule is single-strandedRNA molecule is single-stranded DNA is double-stranded

4. Three Types of RNA Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomesMessenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes Ribosomal RNA (rRNA), along with protein, makes up the ribosomesRibosomal RNA (rRNA), along with protein, makes up the ribosomes Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesizedTransfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized

5 Protein Synthesis   The production or synthesis of proteins happens in two phases: Transcription & Translation DNA  RNA  Protein

6 During transcription, RNA polymerase enzyme binds to a promoter on DNA and separates the DNA strands A promoter is a specific nucleotide sequence of DNA where the RNA polymerase binds and starts transcription. RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA Once the Polymerase reaches a terminal signal (the stop sign), the RNA polymerase releases the RNA and DNATranscription

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8 The Genetic Code Three adjacent nucleotides (letters) in mRNA codes for a specific amino acid (word) A codon designates an amino acid An amino acid may have more than one codon There are 20 amino acids, but 64 possible codons Some codons tell the ribosome to stop translating

9 The Genetic Code Use the code by reading from the center to the outside Example: AUG codes for Methionine

10 Translation Translation is the process of decoding the mRNA into a polypeptide chain Ribosomes read mRNA 1 codon at a time and construct the proteins tRNA carrying the amino acid specified by the codon binds and a peptide bond is formed between the two amino acids. This process continues until a stop codon is reached. The ribosome then falls apart. du/content/molecules/tran scribe/

11 Codons and Anticodons The 3 bases of an anticodon are complementary to the 3 bases of a codon Example: Codon ACU Anticodon UGA UGA ACU

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PROTEIN SYNTHESIS ANIMATION 13 v=WgvnFYyJGZQ v=itsb2SqR-R0www.youtube.com/watch? v=itsb2SqR-R0 /protein/overview.htm