I will understand the general pathway of transcription and translation Biology MT 5: Protein Synthesis Bullet 1 and 2: I will understand the general pathway of transcription and translation Biology Copyright Pearson Prentice Hall

12-3 RNA and Protein Synthesis “making a protein” Step 1. Transcription Step 2. Translation DNA to mRNA mRNA to protein Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of RNA What are the three main types of RNA? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of RNA Types of RNA There are three main types of RNA: messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of RNA The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Messenger RNA (mRNA) carries copies of DNA with instructions to make proteins. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of RNA Amino acid The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Transfer RNA During protein construction, transfer RNA (tRNA) transfers each amino acid to the ribosome. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Types of RNA Ribosome Ribosomal RNA The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Ribosomal RNA is combined with proteins to form ribosomes. Ribosomes are made up of proteins and ribosomal RNA (rRNA). Copyright Pearson Prentice Hall

12-3 RNA and Protein Synthesis “making a protein” Step 1. Transcription Step 2. Translation DNA to mRNA mRNA to protein Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Transcription What is transcription? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Transcription Transcription - One strand of DNA being copied into one piece of mRNA - Occurs in the nucleus - DNA  mRNA During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. Copyright Pearson Prentice Hall

Steps to Transcription 4. RNA polymerase makes pre- mRNA by joining RNA base pair to DNA 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 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 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Transcription RNA RNA polymerase DNA During transcription, RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Translation What is translation? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Translation Messenger RNA is transcribed in the nucleus, and then enters the cytoplasm where it attaches to a ribosome. Nucleus During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA 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. 1st tRNA unloads amino acid to the 2nd tRNA 5. 1st tRNA then unbinds from mRNA 6. Results in a chain of amino acids (protein!) 7. Cycle continues until stop codon reached During transcription, RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Translation The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA. Lysine Phenylalanine tRNA Methionine Ribosome During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA Start codon Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Translation Protein Synthesis Lysine tRNA During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA Translation direction Ribosome Copyright Pearson Prentice Hall

Amino acids within a polypeptide Genes and Proteins Codon Codon Codon 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. Single strand of DNA Codon Codon Codon mRNA This diagram illustrates how information for specifying the traits of an organism is carried in DNA. 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, and proteins play a key role in producing an organism’s traits. Alanine Arginine Leucine Amino acids within a polypeptide Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Genetic Code Q: How do I find the amino acids that link together to form a protein? A codon is a group of three nucleotides on messenger RNA that specify a particular amino acid. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Genetic Code A codon consists of three consecutive nucleotides on mRNA that specify a particular amino acid. A codon is a group of three nucleotides on messenger RNA that specify a particular amino acid. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Genetic Code The genetic code shows the amino acid to which each of the 64 possible codons corresponds. To decode a codon, start at the middle of the circle and move outward. Copyright Pearson Prentice Hall