Questions:

1. Describe the process of transcription: unwinding, complementary base pairing, separating

Unwinding: The first step in transcription is the unwinding and unzipping of a specific section of DNA which happens when the DNA double helix unwinds, and the two strands of DNA separate, and hydrogen bonds between the bases break. This step is achieved by the enzyme DNA helicase.

Complementary base pairing: This step of transcription involves RNA polymerase which will connect new RNA nucleotides to move and pair along the DNA strand by forming new hydrogen bonds.

Separating: The final step of transcription occurs after the mRNA molecule is altered, the mRNA leaves the nucleus and enters the cytoplasm. The DNA molecule the rewinds and returns to its natural double helix form, and the RNA separates.

This picture shows the transcribed DNA which was achieved when RNA polymerase (the yellow sheet of paper in the yellow corner) connects the appropriate RNA bases (U, T, G, C) to the DNA strand.

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

Today’s model was successful in modelling the steps of transcription because we were able to physically manipulate the paper pieces and see how each step advances to the next, allowing for a better understanding on how the concept works in our bodies. Our models were able to show DNA unzipping and unwinding into two strands however it simultaneously showed the different enzymes required to achieve each step of transcription, which was an area that I struggled with before the activity. Even though our model was pretty accurate for the most part, it was inaccurate when it came to showing the last step of transcription, which is when the mRNA leaves the nucleus and floats into the cytoplasm.

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

Initiation: During this process of translation, the mRNA is held by the ribosome (the pink piece of paper). The codon AUG is always considered the start codon and is read by the “P-site” where the matching and appropriate tRNA brings over and pairs it with an amino acid.

In the picture above we see that translation started at the codon AUG, where the tRNA brought its matching amino acid.

 

Elongation: As the above step continues to take place, every amino acid is attached and the amino acids form a chain that continuously grows. The “A-site” on the right reads the next mRNA codon and brings in the matching tRNA, where it attaches. The tRNA in the “P-site” which is located on the left, detached from the ribosome allowing for the following tRNA to move into its place.  This is when the accumulated amino acid chain transfers all of the existing amino acids to the new tRNA. This lengthens the amino acid polypeptide chain which eventually creates a protein which is what the cells read to perform functions.

This image shows both the “A-site” and “P-site” and when comparing it to the image below, the transferral of the amino acid chain.

Termination: As the ribosome (the pink piece of paper) approaches a stop codon, it stops the translation process since there is no tRNA for a stop codon. The ribosome then lets go of mRNA and the tRNA lets go of the polypeptide chain, forming a protein.

The picture above shows the final step of translation which is termination and the polypeptide chain is separated from the tRNA to form a protein.

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

Just like the activity that we did to show the steps of transcription, this model was also successful in demonstrating each step in a visual way. I am a visual learner so this process really allowed me to wrap my head around what was going on during each process. I was able to see how the amino acids were transferred from each site to form a polypeptide chain which later created an entire protein. Our model was inaccurate because it was not to scale which made it a bit confusing when trying to understand each section of the process. Another flaw was that we are not able to see the bonds form between the tRNA and the amino acids which would have been helpful as this explains why they are attracted. Even with these flaws, this activity still helped me understand more in-depth and visualise each step of translation.

This activity helped me to visualize how amino acids become a chain. Also, how the tRNA moves in and out of the ribosome. Our model was inaccurate for the process of initiation because we were not able to see the subunits very distinctly.

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