Transcription You’re made of meat, which is made of protein. Protein Synthesis Transcription You’re made of meat, which is made of protein.

Transcription “Something written, especially copied from one medium to another, as a typewritten version of dictation.” Enzymes make an RNA copy of a portion of DNA. The “message” from DNA is transcribed as RNA. Click image to view movie

Transcription A DNA strand RNA strand RNA strand C B DNA strand

Transcription Prokaryotic cells, no nucleus, mRNA made in cytoplasm.

RNA Processing Not all nucleotides in DNA codefor proteins. Contain non-coding sequences, called introns. Kind of like ads in a magazine (not really information you need to read the magazine articles.)

RNA Processing Regions containing protein code called exons because expressed. Only about 5% of DNA is exons. Introns partly “junk” and partly serve regulatory functions.

RNA Processing Both introns and exons are transcribed. Introns must be removed before mRNA can code for a protein.

RNA Processing Enzymes cut out introns and paste exons back together. Like removing all the ads from a magazine. mRNA leaves nucleus goes to ribosomes.

The Genetic Code Codon - Three nitrogenous bases in mRNA code for one amino acid. DNA - GAG CAT TAG ACT TAC GAT GAC mRNA - CUC GUA AUC UGA AUG CUA CUG

The Genetic Code How many possible combinations of nucleotides are there in a 3 nucleotide Codon? Each base can be used more than once Different orders of combinations count as different (AAC is different from CAA) 4 x 4 x 4 = 64

The Genetic Code The Messenger RNA Genetic Code Second Letter U C A G First Letter Third Letter Second Letter U C A G U Phenylalanine (UUU) Serine (UCU) Tyrosine (UAU) Cysteine (UGU) U Phenylalanine (UUC) Serine (UCC) Tyrosine (UAC) Cysteine (UGC) C Leucine (UUA) Serine (UCA) Stop (UAA) Stop (UGA) A Leucine (UUG) Serine (UCG) Stop (UAG) Tryptophan (UGG) G C Leucine (CUU) Proline (CCU) Histadine (CAU) Arginine (CGU) U Leucine (CUC) Proline (CCC) Histadine (CAC) Arginine (CGC) C Leucine (CUA) Proline (CCA) Glutamine (CAA) Arginine (CGA) A Leucine (CUG) Proline (CCG) Glutamine (CAG) Arginine (CGG) G A Isoleucine (AUU) Threonine (ACU) Asparagine (AAU) Serine (AGU) U Isoleucine (AUC) Threonine (ACC) Asparagine (AAC) Serine (AGC) C Isoleucine (AUA) Threonine (ACA) Lysine (AAA) Arginine (AGA) A Methionine;Start (AUG) Threonine (ACG) Lysine (AAG) Arginine (AGG) G G Valine (GUU) Alanine (GCU) Aspartate (GAU) Glycine (GGU) U Valine (GUC) Alanine (GCC) Aspartate (GAC) Glycine (GGC) Glycine (GGC) C Valine (GUA) Alanine (GCA) Glutamate (GAA) Glycine (GGA) A Valine (GUG) Alanine (GCG) Glutamate (GAG) Glycine (GGG) G

The Genetic Code Some provide instructions. Both UAA and UAG code for STOP, which signals the end of the gene. Multiple codons = same amino acid. UUU and UUC both code for Phenylalanine If there is a mutation/mistake it might not cause a problem

The Genetic Code All organisms use the same genetic code. UUU codes for phenylalanine in redwood trees, bacteria, and you and me. Provides evidence that all life on Earth is related: every living thing evolved from a common ancestor instead of multiple ancestors.

Translation: From mRNA to Protein “A communication in a second language having the same meaning as the communication in a first language” Converting a sequence of nitrogenous bases in mRNA into a sequence of amino acids.

Summary Diagram