Transcription and Translation

1. TranscriptionandTranslation

2. Transcription • Remember that the Nitrogen bases found in DNA and RNA are part of a code System that Controls the synthesis of all Proteins. • The Nitrogen bases act like letters in the alphabet. The words in this nucleotide language are always three nucleotides (letters) long and are called a triple codon. • There are 64 combinations (words) possible. Each triple codon codes for one specific amino acid.

3. Amino acids are the subunits that make up proteins. • There are 20 different amino acids, therefore each amino acid must have at least one triple codon. • One codon tells the cell were the directions for making a protein start (AUG). • Three codons tell the cell were the protein directions stop (UAA) (UAG) (UGA). • There are a few nonsense codons that don’t mean anything also.

4. Anti-codon to Protein

5. Examples of codons: Circle the triple codons below • CGTACGAAACAGTCT • CGTACGAAACAGTCT • DNA, which contains all the hereditary information (directions for proteins) can not leave the nucleus. But proteins are made in the cytoplasm (cytosol) of the cell. • So a copy of the information in the DNA is made (mRNA) and that copy can leave the nucleus and go into the rest of the cell to make proteins.

6. The mRNA made is called the messenger RNA. The process of transcription is similar to replication. • 1. First the DNA unzips with the help of helicases. • 2. Then RNA polymerase pairs RNA nucleotides with one side of the DNA strand.

7. 3. As the mRNA is made, it forms a long Chain that is not permanently attached to the DNA. • 4. The DNA zips back up when the Polymerase reads a stop signal and the newly made mRNA goes out into the cytoplasm of the cell. • Links • Transcription • Transcription 3

8. Translation • Remember that there are two other kinds of RNA besides messenger RNA (mRNA). • They are: • Transfer RNA (tRNA) • Ribosome RNA (rRNA)

9. Start • It is tRNA’s Job to find the amino acids floating around in the cytoplasm and attach them in the correct order to make the protein according to the directions on the mRNA. • Each tRNA has a specific anti-codon which is the opposite nucleotide sequence for one of the codons located on the mRNA. • The tRNA has to find the amino acid that matches it’s anti-codon and then find the mRNA to deliver the amino acid to the appropriate spot. Valine lysine Glutamic acid proline stop

10. The ribosome moves along the mRNA and helps the tRNA attach. • The ribosome hooks and the growing amino acid chain together so the tRNA is free to go find another amino acid when it is done delivering.

11. The ribosome attaches on the mRNA at the start codon (AUG) and falls of at one of the three stop codons (UAA) (UAG) (UGA).

12. Remember that proteins are made from combinations of the 20 amino acids. • Some proteins have as little as 30 amino acids and some are as large as one million amino acids. • When a stop codon signals the end of a gene, the chain of amino acids falls off and fold into a protein. • Translation 2 • Real time molecules link • Boseman overview

14. Protein Nucleotide Nitrogen base Molecule Adenine Cytoplasm Codon Gene Amino acid Thyamine Guanine Nucleus DNA mRNA tRNA rRNA Anti-codon Uracil Cytosine Work with the person sitting next to you to sort the following vocabulary words:

15. To do in class and finish as homework • For p206-212 of handout • Highlight the main idea of each paragraph • Create a timeline for transcription • Create a timeline for translation • Compare/contrast transcription and translation using a Venn Diagram • Write a 5-6 sentence summary of the handout • Questions 1-8 on notes