Warm-Up 3/12/13 After transcription, an mRNA molecule with the sequence A U A C G C A G U was created. What was the sequence of the original DNA strand?

Yesterday we introduced transcription. Today, we’ll talk about… Translation!!!

While RNA is single-stranded, it does not “combine” to make double-stranded DNA.DNA and RNA are two entirely different molecules. RNA contains ribose sugar while DNA contains deoxyribose, and RNA contains uracil (U) instead of thymine (T).

Translation What? The ribosome uses information from mRNA to produce proteins The order of nucleotides in each gene codes for the order of amino acids which make up a specific protein

Translation Where? Takes place at the ribosome (in the cytoplasm or at the rough ER) Why? So that DNA instructions for a gene can be converted into a protein which will result in a specific trait (like hair color)

Translation How? RNA  Proteins

Steps in Translation 1. mRNA moves to the cytoplasm and finds a ribosome, and the mRNA chain begins to move through the ribosome

Steps in Translation 2. As it moves through the ribosome, mRNA codons are read and deciphered *Each mRNA codon codes for a specific amino acid.  

Steps in Translation 3. tRNA molecules bring amino acids to the ribosome -- Each tRNA carries only one amino acid -- The tRNA has 3 bases that make up an anticodon (which is complementary to one mRNA codon)

Steps in Translation 4. At the ribosome, the amino acid is transferred to a growing polypeptide chain (protein) Peptide bonds are added between each amino acid to connect them and form a string

Steps in Translation 5. More amino acids are added to the growing chain until the ribosome reaches a stop codon Final Product: A PROTEIN!

Steps in Translation 5. Depending on the order of amino acids, the protein will fold up into a specific shape Final Product: A PROTEIN!

ribosome

How to read a codon table…

Let’s Practice Given the mRNA sequence… ACU GGC UAU CCA GCU UAG What is the correct amino acid sequence? Thr Gly Tyr Pro Ala STOP

Let’s Practice Given the mRNA sequence… CCC AGC GAA GUG AUC UGA What is the correct amino acid sequence? Pro Ser Glu Val Ile STOP

Let’s Practice Given the mRNA sequence… AUG CUA CGU UGG CAU UAA What is the correct amino acid sequence? Met Leu Arg Trp His STOP

Let’s Practice Given the mRNA sequence… AAC UGC AAA GCG CAU UGA What is the correct amino acid sequence? Asn Cys Lys Ala His STOP

Let’s Practice Given the mRNA sequence… AUU AUA UCU AGU UCA UAG What is the correct amino acid sequence? Ile Ile Ser Ser Ser STOP