- RNA molecules
- RNA polymerase and the process of transcription
- Principles of translation and the genetic code
- Translation in the ribosome
1. Before you begin this topic, you should know the structure and properties of RNA molecules, as well as proteins.
2. The first thing you should know is what happens during translation. Review your textbook and your notes and write down a definition of translation. While the lecture notes do not provide a formal definition of translation, you can look at the definition of transcription to help you decide what should go into your translation definition. You should mention the template, the product, where does the process occur, etc. Study your definition and your notes and see if you can improve/refine it. When you are all done, answer the following questions on a piece of paper (write a paragraph, which describes translation, starting with your definition, which will probably contain some of the answers):
- Where does translation occur?
- What is the template in translation and how is it read (direction)?
- What is the product of translation?
- Why do we call this process translation?
- Why is the genetic code needed?
- What is a codon?
- Why are codons made of three nucleotides?
- What is a tRNA?
- Why are tRNAs needed?
3. The genetic code is very important, as it allows cells to use the information stored in the sequence of DNA to specify the sequence of proteins. Study the genetic code and its features in your textbook and in your notes. When you are done, you should be able to answer the following questions:
- How many codons are in the genetic code?
- What is a start codon?
- What are the two functions of the codon AUG?
- What is a stop codon?
- What are the three stop codons?
- Why do we say the genetic code is degenerate (or redundant)?
- Why is the genetic code degenerate (redundant)?
- How does the redundancy of the genetic code protect cells from mutations?
4. Now that you have mastered the genetic code, one question remains before you can understand the actual process of translation: how does a cell know which amino acid corresponds to a given codon? The answer is, of course, using tRNAs. Review your textbook and notes and answer the following questions?
- What is the structure of a tRNA?
- What is an anticodon?
- How many anticodons does a tRNA have?
- What is tRNA loading?
- How many different amino acids can a tRNA be loaded with?
5. Let's put our knowledge of the genetic code to practice. Below is a double strand of DNA. Copy the DNA on a piece of paper and then, based on all the info you have so far (you will need your knowledge of transcription, as well), write the mRNA that will be produced from it, and then translate that mRNA into the protein that will be made. Check your mRNA and protein by mousing over the word ANSWER below. Hint: you will have to identify the template strand by looking for the start and stop codons on the mRNA made from it.
ANSWER
6. You are now ready to move to the next topic of this sub-unit, which deals with the actual process of translation.