RNA Transcription Model
1. How does mRNA differ from DNA?
mRNA is different from DNA because mRNA is made up of ribose sugar instead of deoxyribose sugar like DNA. DNA also contains thymine as a pyrimidine while the mRNA pyrimidine base has uracil. mRNA is also only single-stranded, single backbone, and DNA is double stranded, double backbone.
2. Describe the process of transcription.
The process of transcription is broken down into three parts:
Unwinding & Unzipping
First, the DNA unwinds and the unzipping happens only at the specific location of the genes required for the information needed for the instructions to build the gene. As shown in the picture, it again does not unzip as a whole, but only a section on the DNA unzips. RNA gets its information from the sense strand, and the sense strand carries information for protein synthesis.
Complimentary Base Pairing
As shown in the picture, RNA polymerase enzyme (the fuzzy peach), facilitates the bonding between the nucleotides in the unwinded spot of the DNA. The pyrimidine uracil is bonded to adenine while guanine and cytosine remain together. The information gets copied exactly because the red RNA strand base pairs with the blue nitrogen base on the sense strand.
Separation
RNA is now separated from the DNA and the DNA zips back up like normal, and reforms the original double helix shape. mRNA develops during replication and the unnecessary sections are removed to make sure it will exit through the nuclear pore.
3. How did todays activity do a good job of modelling the processs of RNA transcription? In what ways was our model inaccurate?
In this activity, you could clearly see the one strand for RNA and the 2 strand DNA. The double helix shape was easy to form by twisting the pipecleaners. The colours of the pipexcleaners also represented the DNA versus RNA well by using blue and red. The colours of beads were good because I was able to see which base bonded with what due to the coorisponding colours.
Inaccuracies include the sense strand connecting to the RNA strand. The RNA strand should enter inside the double bond of DNA. The RNA strand should not completely replace the complimentary strand.
Protein Synthesis Model
1. Describe the process of translation: initiation, elongation and termination.
Initiation
This process is where the ribosome, which is represented by the red paper, holds the mRNA and reads the start condon. The ribosome holding mRNA bonds to another subunit ribosome and then finds the AUG and the codon on the mRNA (strand) which initiates the order of amino acids. The AUG codon pairs with the UAC anticodon, on the green paper which is the tRNA.
Elongation
The ribsome then read the codons on the mRNA strand, specificating the amino acids and adding tRNA molecules. The first codon is moved to the P-site an the second codon is to go to the A-site. Because both spots are then filled the codon transfers and the tRNA at the P-site floats away and makes way for the codon to move down. This is repeated and the amino acids keep binding. Then a polypeptide chain is formed creating the beginning of a protein, continuing to repeat until the tRNA comes to the STOP codon.
Termination
This is the last step. After STOP condon is found, it does not have a match tRNA so there connot be an amino acid created to add to the chain. The polypeptide releases by hydrolysis and the ribosomes are released and split from the sub-units it was in.
2. How did today’s activity do a good job of modelling the process of translation? In what ways was our model inaccurate?
The activity had great representation and visualization of translation. Everything was separated by colour which made it easy to see the different structures involved. However, all the amino acids were the same shape, so it was not accurate. Also the subunits were not shown and only had one ribosome. We were unable to see the ribosome break down.