End Show Slide 1 of 39 Copyright Pearson Prentice Hall Biology Protein Synthesis: I will understand the general pathway of transcription and translation

End Show Slide 2 of 39 Copyright Pearson Prentice Hall 12-3 RNA and Protein Synthesis Protein Synthesis: “ making a protein ” Step 1. Transcription Step 2. Translation DNA to mRNAmRNA to protein

End Show 12–3 RNA and Protein Synthesis Slide 3 of 39 Copyright Pearson Prentice Hall Types of RNA What are the three main types of RNA?

End Show 12–3 RNA and Protein Synthesis Slide 4 of 39 Copyright Pearson Prentice Hall Types of RNA There are three main types of RNA: messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA)

End Show 12–3 RNA and Protein Synthesis Slide 5 of 39 Copyright Pearson Prentice Hall Types of RNA Messenger RNA (mRNA) carries copies of DNA with instructions to make proteins.

End Show 12–3 RNA and Protein Synthesis Slide 6 of 39 Copyright Pearson Prentice Hall Types of RNA During protein construction, transfer RNA (tRNA) transfers each amino acid to the ribosome. Amino acid Transfer RNA

End Show 12–3 RNA and Protein Synthesis Slide 7 of 39 Copyright Pearson Prentice Hall Types of RNA Ribosomes are made up of proteins and ribosomal RNA (rRNA). Ribosome Ribosomal RNA

End Show Slide 8 of 39 Copyright Pearson Prentice Hall 12-3 RNA and Protein Synthesis Protein Synthesis: “ making a protein ” Step 1. Transcription Step 2. Translation DNA to mRNAmRNA to protein

End Show 12–3 RNA and Protein Synthesis Slide 9 of 39 Copyright Pearson Prentice Hall Transcription What is transcription?

End Show 12–3 RNA and Protein Synthesis Slide 10 of 39 Copyright Pearson Prentice Hall Transcription - One strand of DNA being copied into one piece of mRNA - Occurs in the nucleus - DNA  mRNA

End Show 12–3 RNA and Protein Synthesis Slide 11 of 39 Copyright Pearson Prentice Hall Steps to Transcription 1. Part of DNA unwinds in nucleus 2. RNA polymerase binds to promoter (T-A-T-A) (“start”) region on DNA strand 3. RNA polymerase unzips DNA strand 4. RNA polymerase makes pre- mRNA by joining RNA base pair to DNA 5. RNA polymerase reaches “stop” region and pre- mRNA released from DNA 6. Pre-mRNA removes introns (unwanted mRNA) to make mature mRNA 7. mRNA exits the nucleus into cytoplasm

End Show 12–3 RNA and Protein Synthesis Slide 12 of 39 Copyright Pearson Prentice Hall Transcription RNA RNA polymerase DNA

End Show 12–3 RNA and Protein Synthesis Slide 13 of 39 Copyright Pearson Prentice Hall Translation What is translation?

End Show 12–3 RNA and Protein Synthesis Slide 14 of 39 Copyright Pearson Prentice Hall Translation Nucleus mRNA Messenger RNA is transcribed in the nucleus, and then enters the cytoplasm where it attaches to a ribosome.

End Show 12–3 RNA and Protein Synthesis Slide 15 of 39 Copyright Pearson Prentice Hall Translation 1. Ribosome attaches to mRNA at AUG codon 2. Ribosome “decodes” codon and brings in loaded tRNA 3. Ribosome moves and decodes next codon and brings in loaded tRNA 4. 1 st tRNA unloads amino acid to the 2 nd tRNA 5. 1 st tRNA then unbinds from mRNA 7. Cycle continues until stop codon reached 6. Results in a chain of amino acids (protein!)

End Show 12–3 RNA and Protein Synthesis Slide 16 of 39 Copyright Pearson Prentice Hall Translation Lysine tRNA Phenylalanine Methionine Ribosome mRNA Start codon The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA.

End Show 12–3 RNA and Protein Synthesis Slide 17 of 39 Copyright Pearson Prentice Hall Translation Protein Synthesis tRNA Ribosome mRNA Lysine Translation direction

End Show 12–3 RNA and Protein Synthesis Slide 18 of 39 Copyright Pearson Prentice Hall Genes and Proteins IN A NUTSHELL: The sequence of bases in DNA is used as a template for mRNA. The codons of mRNA specify the sequence of amino acids in a protein. Codon mRNA Alanine Arginine Leucine Amino acids within a polypeptide Single strand of DNA

End Show 12–3 RNA and Protein Synthesis Slide 19 of 39 Copyright Pearson Prentice Hall The Genetic Code Q: How do I find the amino acids that link together to form a protein?

End Show 12–3 RNA and Protein Synthesis Slide 20 of 39 Copyright Pearson Prentice Hall The Genetic Code A codon consists of three consecutive nucleotides on mRNA that specify a particular amino acid.

End Show 12–3 RNA and Protein Synthesis Slide 21 of 39 Copyright Pearson Prentice Hall The Genetic Code AUG = Methionine

End Show 12–3 RNA and Protein Synthesis Slide 22 of 39 Copyright Pearson Prentice Hall The Genetic Code AAC = asparagine