12-3 RNA & Protein Synthesis Vocabulary: Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA) Transcription Polymerase Promoter Codon Translation Anticodon Key Concepts: What are the 3 main types of RNA? What is transcription? What is translation?

What do proteins do for the body? Proteins are very different and do many different things! They control chemical messages in cell; direct the synthesis of carbohydrates, lipids, and nucleotides; enzymes; give the cell structure (shape) and movement

RNA Like DNA= made of nucleotides disposable copy of DNA segment 3 differences 1) sugar= ribose 2) single stranded 3) instead of the base thymine (T), RNA uses uracil (U)

Transcription Transcribe: to make a copy Step #1 (of 2) of protein synthesis Transcribe: to make a copy Taking DNA information (gene instructions) and making it into mRNA, which can leave the nucleus and go to the ribosomes in the cytoplasm messenger RNA= mRNA (1 type of RNA) special base sequences in DNA are recognized by RNA as “start” and “stop” signals “Start” sequence called promoter region of DNA

Details of the Process 1. RNA polymerase attaches to DNA at the site where instructions for the needed protein begins & it separates the 2 DNA strands

2. RNA polymerase makes the mRNA strand using complimentary base-pairing rules

Remember…there aren’t “T” bases in RNA “C” binds with “G” DNA “A” binds with RNA “U”

Which strand was copied? A or B

3. when RNA polymerase reaches the end or "STOP" part of the genetic code for that protein, it releases itself 4. DNA re-zips   5. finished mRNA (message) leaves the nucleus and goes to a ribosome in the cytoplasm

What are the three main differences between DNA and RNA?  

What are the two functions of RNA Polymerase?

Bases are grouped by 3 Called a codon (“code”)

Transcription Translation

Transcription ends with mRNA which will leave the nucleus and go to the cytoplasm So… if Transcription is the first step of Protein Synthesis, what happens next in the cytoplasm?

TRANSLATION Making a protein (string of amino acids): translating from the language of nucleic acids into a polypeptide How does it go from mRNA (copy of DNA) to amino acids (building blocks of proteins)? A group of 3 mRNA bases makes up a “codon” (think of as a “code word”) each codon specifies a certain amino acid there are “start” and “stop” codons

tRNA Amino acid tRNA anticodon mRNA codon

The Mechanism... mRNA attaches onto the ribosome 3 nucleotides of mRNA = codon 2nd kind of RNA= ribosomal RNA (rRNA) makes up the most of the ribosome

The Mechanism continued... 3rd kind of RNA= transfer RNA (tRNA) carries amino acids to the ribosomes (amino acids join together) there are 64 different tRNA molecules (more than 1 for each amino acid) REDUNDANCY of the CODE!! (it repeats itself!) 3 nucleotides of tRNA that “match” or compliment the mRNA = anticodon

amino acid tRNA anticodon codon (mRNA)

The Mechanism continued... By matching the codon of mRNA to the anticodon of tRNA, the correct amino acid is put into place Next tRNA goes here!!!!

The Mechanism continued... a peptide bond is formed between the 2 amino acids

The Mechanism continued... protein chain continues to grow until a “stop” codon is reached on the mRNA no tRNA exists for “stop” codons

The end of the Mechanism... the protein is now finished & released!!

PROTEIN SYNTHESIS: All At Once

PROTEIN SYNTHESIS DNA Step 1. TRANSCIPTION (nucleus) mRNA Step 2. TRANSLATION (ribosome) tRNA PROTEIN

Protein Synthesis: the whole process

What stops translation?  

What is the goal of translation?  

Transcription and translation are the two steps of ________________