Protein Synthesis: Transcription and Translation FQ: How does the code in our genes (sections of DNA) build proteins for our cells? Today we are going to explore the process of protein synthesis. You will be introduced to the vocabulary involved in understanding this process and gain a perspective the “big picture” on how protein synthesis works.

Ch. 13 FQ: What are the main differences between DNA and RNA FQ: What are the steps to go from DNA to protein? ET: Open your books to the chapter on protein synthesis 13… What are the 3 important differences between RNA and DNA

DNA RNA Protein What does DNA do? Instructions Controls the production of proteins DNA RNA Protein Transcription Translation

Ribonucleic Acid vs. Deoxyribonucleic Acid DNA RNA Deoxyribose Sugar Double Stranded Thymine Ribose Sugar Single Stranded Uracil DNA DNA RNA ATTGCGGTTAA TAACGCCAATT AUUGCGGUUAA

Types of RNA mRNA – messenger RNA takes the message from the DNA to the ribosome to be translated into a protein rRNA – ribosomal RNA is part of the ribosome that translates the protein tRNA – transfer RNA transfers amino acids to the ribosome as it is specified by the 3 base pair sequence (codon) from the mRNA PROTEIN SYNTHESIS!!

Transcription TRANSCRIPTION: Part of the nucleotide sequence DNA is copied into an RNA sequence. DNA unzipped by RNA Polymerase One strand of DNA is used as a template to make RNA strands

How does the RNA polymerase enzyme know where to start? Promoters are regions of the DNA sequence that tell RNA polymerase where to bind and start transcription. The base sequence at those “promoter” regions signal the enzyme where to bind Transcription

Lets practice transcribing mRNA Use the following DNA Templates to transcribe the mRNA strands DNA: ATG TTC GCG CGT DNA: GCA TGC CTA CCG DNA: AGA CGT ATA GAT

Lets practice DNA codon: ATC mRNA codon: UAG tRNA anticodon: AUC RNA i

Translation Where: Ribosome What: it takes the mRNA information and builds a protein Who: 3 base pairs make a codon = the code for an amino acid tRNA brings the an amino acid that has the compliment to mRNA = Anticodon Ex. If the mRNA codon in the ribosome is AUG – tRNA brings UAC to the ribosome. AUG is the code for an amino acid Q: What do you notice about the tRNA anticodon? What does it look like?

PROTEINS What monomers make up the polymer protein? AMINO ACIDS!! Different combinations of amino acids make up different proteins Q: How can the order of nitrogenous bases in DNA and RNA be translated into amino acids?

Translation mRNA contains 4 different nitrogenous bases: A, U, C, and G Combinations of 3 of these bases code for one particular amino acid These combinations are called CODONS

What amino acid would form from the following codons? GUC=___________ UGG=___________ CAG=___________ CAA=___________ UUU=___________

Steps of Translation mRNA is transcribed from DNA in the nucleus and sent into the cytoplasm mRNA attaches to a ribosome. Codons pass through the ribosome and the correct amino acids are brought in by tRNA creating a polypeptide chain

Steps of Translation The ribosome forms peptide bonds between the amino acids. The chain continues until the ribosome reaches a stop codon and releases the protein

Translation

13.3 - Mutations LT: Today I will… Define mutations and describe the different types of mutations ET: Quiz! Take out a half sheet of paper and write your name at the top. *you will need a translation chart from your book or on the pink card.

Quiz DNA Gene Sequence: TAC GCA TAC ATT Transcribe the RNA: Write the Anti codons: Translate the mRNA Codons:

What kind of problems could arise if one nucleotide in a DNA sequence is transcribed incorrectly? GGCGCGGTTAAG CCGCGCCAAUUC GGCGCGGTTAAG CCGCGCUAAUUC Proline Proline Arginine Arginine Glutamine STOP Proline

2 types of Mutations Gene mutations Substitution Insertion deletion Chromosomal mutations Deletion Duplication Inversion translocation

Gene Mutation Mutations that occur only to a single gene on the chromosome Frameshift (they shift the segment that is being read) Ex. Insertions and deletions Point: only one or a few base pairs are changed Ex. Substitution

Chromosomal Mutations Changes part of the chromosome which may disrupt many genes on the chromosome

What are Mutagens? Chemical or physical agents in the environment that cause mutations

Please take out your mutations worksheets from Friday