Protein Synthesis

How is mRNA different than DNA? 

It is single stranded and short.

Contains sugar ribose instead of sugar phosphate.

Instead of thymine, has uracil, which bonds with DNA adenine.

Describe the process of transcription. 

1. A specific section of NDA unwinds, exposing one gene only. This happens when running low on protein. The picture shows a section, however in the rest of the activity we undid the whole DNA molecule to allow mRNA to work.

 

1. Along 1 strand, complimentary RNA bases bond, through hydrogen bonds. (Uracil, which is shown with the brown bead, will bond with DNA’s adenine.) Now, only 1 strand of DNA has the instructions for which RNA nucleotides will bond to, this is the sense strand.

1. Adjacent nucleotides form covalent bonds and build RNA backbone, through RNA polymerase (Represented by the fuzzy peach), the enzyme in which initiates this process.

1. RNA is released and moves out of the nuclear to the mitochondria. DNA then reforms into the double helix.

 

How did today’s activity do a good job of modelling the process of RNA transcription? In what ways was our model inaccurate? 

It showed the basis of the steps of transcription, but was not detailed enough. First of all, when one section of DNA is supposed to unwind exposing one gene, was not showed accurately as we undid our entire DNA molecule. We assumed our molecule was one gene but it doesn’t accurately show how many genes are contained in one molecule of DNA. As well, RNA must be refined in the nucleus before being released, which this activity did not show. Adding on to that, this activity was good at showing the basic structure of DNA, but didn’t show the whole picture of why DNA is structured like it is, and how transcription, as well as translation works.

Describe the process of translation: initiation, elongation, and termination. 

Initiation: mRNA binds to the small ribosome subunit, then the two ribosomes subunits bind together. The first side of the ribosome, the P site, reads the 1st codon. If the first codon is AUG, the ribosome will continue to read the mRNA.

Elongation: As the ribosome holds mRNA, the tRNA binds to the site with the anti – codon, holding one of the 20 amino acids. tRNA binds to the P site as another tRNA binds to the A site. When the other tRNA binds the A site it causes the amino acid to let go of tRNA and bind to the neighbouring amino acid.

  

Termination: The elongation cycle continues until mRNA reads a stop codon. Which is a code that has no matching tRNA, therefore no new amino acid is added to the chain and the ribosome dissociates into its 2 subunits and the polypeptide is released.   Our protein made DNA polymerase, which is very interesting because we made a protein that we used in order to create this protein.

 

How did today’s activity do a good job of modelling the process of translation? In what ways our model inaccurate? 

It did a really good job of showing the simple steps of initiation and elongation, however when it comes to elongation, it was hard to show the continues movement and exactly how tRNA bonds  to the ribosome. It did a good job at showing how the amino acids are carried and put together. It however was difficult to show how the ribosome moves along the mRNA strand and how tRNA stays with the mRNA and switches between each site.