G U A C G U A C C A U G G U A C A C U G UUU UUC UUA UCU UUG UCC UCA Phenylalanine UUA UUG Glutamic acid Glycine UCU UCC UCA UCG Leucine A G U Serine Aspartic acid U C C A G G A G U U C C UAU UAC A Alanine U A C G Tyrosine G A U C C C Stop A A U G G G U U Cysteine Valine A U G C C A Stop U G Tryptophan G G U U Arginine A A C C A Leucine C A C G Serine U U G A A C Lysine C A C Proline U G U G Asparagine G U A C C A U G G U A Histidine C A C Threonine U G Glutamine Arginine Isolucine Methionine What is the amino acid sequence for the codons: GCA UAC CCC GUA? Animated by Jeff Christopherson alanine tyrosine proline valine

Phenylalanine Leucine Serine Tyrosine Stop Cysteine Stop Tryptophan Leucine Proline Histidine Glutamine Arginine Isoleucine Methionine Threonine Asparagine Lysine Serine Arginine Valine Alanine Aspartic Acid Glutamic Acid Glycine

Phenylalanine Leucine Serine Tyrosine Stop Cysteine Stop Tryptophan UUU UUC UUA UUG UCU UCC UCA UCG UAU UAC UAA UAG UGA UGU UGC UGA UGG Leucine Proline Histidine Glutamine Arginine CUU CUC CUA CUG CCU CCC CCA CCG CAU CAC CAA CAG CGU CGC CGA CGG Isoleucine Methionine Threonine Asparagine Lysine Serine Arginine AUU AUC AUA AUG ACU ACC ACA ACG AAU AAC AAA AAG AGU AGC AGG AGA Valine Alanine Aspartic Acid Glutamic Acid Glycine GUU GUC GUA GUG GCU GCC GCA GCG GAU GAC GAA GAG GGU GGC GGA GGG

A G U C

RNA and Protein Synthesis A. The Structure of RNA B. Types of RNA C. Transcription D. RNA Editing E. The Genetic Code F. Translation G. The Roles of RNA and DNA H. Genes and Proteins

Bring amino acids to ribosome Concept Map RNA can be Messenger RNA Ribosomal RNA Transfer RNA also called which functions to also called which functions to also called which functions to mRNA Carry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome from to to make up DNA Ribosome Ribosomes

Transcription RNA polymerase DNA RNA Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase DNA RNA

The Genetic Code

Translation mRNA Nucleus Messenger RNA mRNA Lysine Phenylalanine tRNA Messenger RNA is transcribed in the nucleus. mRNA Lysine Phenylalanine tRNA Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. Methionine Ribosome mRNA Start codon

Translation (continued) The Polypeptide “Assembly Line” The ribosome joins the two amino acids—methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. Growing polypeptide chain Ribosome tRNA Lysine tRNA mRNA Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain. mRNA Translation direction Ribosome

Interest Grabber Determining the Sequence of a Gene DNA contains the code of instructions for cells. Sometimes, an error occurs when the code is copied. Such errors are called mutations.

Interest Grabber continued 1. Copy the following information about Protein X: Methionine—Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP. 2. Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence. 3. Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. 4. Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. 5. Did this single deletion cause much change in your protein? Explain your answer.