Transcription & TranslationTranscription & Translation

Mr. Holmes

Biology

Questions to be answered about transcription: (Be sure to leave space after each question)

1. What is transcription?

2. Where does transcription take place?

3. What are the differences between transcription and replication?

4. What type of RNA is produced in transcription?

5. What is the region where transcription takes place called?

6. Where does transcription stop?

7. What are the non coding regions on mRNA called? Coding regions?

Transcription is the process of turning DNA into mRNA. It functions in the same way as replication. Transcription occurs in the nucleus and base pairs in the same way except for a couple of differences.

The differences in replication and transcription are:

1. The presence of RNA2. The use of uracil and not thymine3. RNA polymerase is the enzyme used and

not DNA polymerase4. RNA has the sugar ribose and not

deoxyribose.

The enzyme RNA polyermase makes a copy of RNA from only ONE of the DNA strands.

The RNA strand is called mRNA and it codes for the production of proteins.

The location where transcription starts is called the promoter region.

The noncoding regions of mRNA are called introns. The coded regions are called exons. Introns are cut out and the exons are glued back together so that translation can take place.

Let’s check out transcription animation!!

Questions to be answered about translation: (Be sure to leave space for the answers)

1. Where does translation take place?

2. What is the product of translation?

3. How many nucleotides are read at a time? What is this called?

4. What are the types of RNA involved besides mRNA? What are their functions?

5. What is the start codon and amino acid being produced to initiate translation?

6. How does translation end?

The mRNA produced from transcription exits through the nuclear pores and enters the cytoplasm.

The final product that is produced in translation is a protein.

What is the monomer of a protein?

In order to make a protein, three nucleotides have to be “read” or translated a time. This grouping of three nucleotides is called a codon. Each codon codes for an amino acid.

Besides mRNA, the other types of RNA used in translation are tRNA and rRNA.

rRNA = ribosomal RNA; these RNA molecules associate with other proteins to form the ribosomes. Each ribosome can accept two tRNAs at a time (carrying amino acids) and one mRNA.

tRNA = transfer RNA; small RNA molecules that carry a specific amino acid at one end and an anticodon region that recognizes and binds mRNA at the other end. The tRNA that binds to that mRNA codon determines what amino acid is added to a protein chain.

The Three RNAs (mRNA, tRNA, and rRNA) all work together to turn the information in DNA into a beautiful, 3-dimestional protein!!!

• The steps of translation: • 1. Initiation: mRNA enters the cytoplasm and becomes associated with

ribosomes (rRNA + proteins).• tRNAs, each carrying a specific amino acid, pair up with the mRNA

codons inside the ribosomes. Base pairing (A-U, G-C) between mRNA codons and tRNA anticodons determines the order of amino acids in a protein.

• 2. Elongation: addition of amino acids one-by-one: As the ribosome moves along the mRNA, the tRNA transfers its amino acid to the growing protein chain, producing the protein - codon by codon!

• 3. Termination: when the ribosomes hits a stop codon - UAA, UGA, or UAG - the ribosome falls apart!

Let’s Check out an animation of Translation!!!