Protein Synthesis

1. Protein Synthesis Mrs. Harlin

2. 3.1.2 • Explain how DNA and RNA code for proteins and determine traits.

3. Transcription Translation Protein Synthesis DNA mRNA Trait Protein

4. Step 1- Transcription Transcription makes an mRNA copy of DNA in the nucleus of the cell. If the DNA reads: TAC GTA GCA The mRNA (messenger) will read: AUG CAU CGU

5. What is the difference? • DNA has T (Thymine) and RNA does not! • Instead RNA has U (Uracil). • If the DNA strand has a T you will still write an A for the RNA like you would do during DNA replication. • If the DNA strand has an A you will write a U for the RNA because RNA does not have T.

6. The Other Differences • 1. So RNA has U’s, DNA has T’s. • 2. RNA is single stranded; whereas, DNA is double stranded. • 3. RNA is made of the sugar ribose; whereas, DNA is made of the sugar deoxyribose.

7. Step 2 Translation • The mRNA goes to a ribosome, made of rRNA, where the amino acids are brought and dropped off by a tRNA (transfer) to make the protein. • If the mRNA reads: • AUG CAU CGU • The tRNA will read: • UAC GUA GCA

8. The Protein • To figure out the sequence of amino acids the protein will have, you must use the mRNA codon chart in your textbook (pg. 211). • Look up the mRNA codons: • If the mRNA reads: • AUG CAU CGU • The amino acids will be: • Start histidine arginine

9. The Protein • The protein is formed by polypeptide chains, which are just amino acids linked by peptide bonds. • Proteins can be structural (forming part of the cells materials) or functional (hormones, enzymes, or chemicals involved in cell chemistry).