Protein Synthesis

Protein Synthesis Process:

  1. Transcription:

Transcription happens in the nucleus. It occurs as the first step when making a protein through using the gene instructions from DNA. An example of a gene is the color pigment of your eye color, or the color and texture of your hair. When converting a DNA message into RNA, DNA must be unwound. After unwinding, an enzyme called the DNA polymerase will read each DNA base sequence and build a mirrored version chain called the mRNA (messenger RNA) by using scattered RNA bases in the nucleus. DNA polymerase connects the complimentary bases together (DNA bases with RNA bases). These RNA bases bond together to form a chain called the mRNA. One important aspect to note is that RNA has a slight change to a certain base compared to DNA.

Since the Adenine of DNA pairs with Thymine, there are no Thymine on RNA but instead, Uracil, so the Adenine will always pair up with Uracil if the DNA base is an Adenine. (Cytosine and Guanine remain the same and still pair with one another in both DNA and RNA).

After transcribing the entire gene into an mRNA, the mRNA can exit the nucleus, since that is preciously its job; but before exiting, the mRNA must be processed, having sections of RNA added or removed. After separating with the DNA, the mRNA leaves the nucleus through one of its pores in the nuclear membrane and flows into the cell’s cytoplasm.

In the photo below, the yellow represents the DNA polymerase building the mRNA, which is represented by the stripped white paper.

  1. Translation:

Translation occurs in the ribosome, where proteins get produced. Within the ribosome, rRNA will read the mRNA to understand what the codes of the mRNA contain and what amino acids the tRNA will need to bring. tRNA (Transfer RNA) carries amino acids, which are also known as the monomer to create a protein.

tRNA and mRNA work together because with each other, they can determine which amino acids are needed. The mRNA attaches itself onto a small ribosomal unit and then 2 other ribosomal unit attaches themselves over as well. tRNA comes in 3 complementary bases, which is also known as an anticodon. The 3 complimentary bases on the mRNA called the codon. There are 20 amino acids, with 64 possible codons. The first codon is usually AUG, which stands for the amino acid Methionine, which is not only known as the first amino acid, but also the initiation stage, officially starting the translation. With the ribosomal unit holding the mRNA down, the tRNA can attach its anticodons onto the mRNA’s codons. After the codon and anticodon’s complimentary bases bond together, the tRNA’s work here is done and exits the ribosome, leaving behind its amino acid. The way amino acids connect with one another is through a peptide bond, creating a chain as more tRNA come in and leave behind the amino acids. This is also known as the elongation stage. When it is time for termination, the final codon is UAA, UAG, or UGA, all sharing the same codon: stop. These codons signify that the translation is complete, and so a protein is made. The chain of amino acids become longer and longer, resulting in an protein (a chain of amino acids). The ribosome will separate into 2 subunits and then the polypeptide is released! After the polypeptide (chain)is formed, the resulting shape of a protein will be formed through folding and shaping so that it will get its 3D form.

The photo above is a model of the mRNA through a ribosome (the rRNA). The ribosome is represented by the Squidward shaped paper, and the mRNA is the white strand passing through.

The two photos above are models of translation occurring. The green T shaped paper represents the tRNA carrying the amino acid, which is the purple marshmallow shaped paper cut out on top of the tRNA. What is happening in the model is that the anticodons are matching with the codons found on the mRNA.

The two photos above is demonstrating that after the anticodon and codon have found each other, the tRNA will exit the ribosome, leaving behind the amino acid, which is then connected with the other lonely amino acids to form a peptide bond.

Lastly, the photo above is the result from protein synthesis: a protein! This is what the polypeptide will form after the chain of amino acids attaching to each other.

 

Questions after model activity:

  1. Working with the models showed me an accurate and direct example of the process of transcription and translation. Through this activity, I was able to have a clearer comprehension of what is protein synthesis. During the transcription part, I think that having the mRNA slide through the DNA polymerase was a really cool and creative way to demonstrate the DNA polymerase creating the mRNA. As for the translation, the models accurately showed what the tRNA functions as, and what happens with the amino acids after the anticodon and codons connected with one another.                                                              Though the photos are a little blurry, I remember I think our group accidentally wrote the mRNA in reverse? Which is why some of the data is inexact and flipped. Personally, I believe the amino acid caused a little confusion for me. I couldn’t understand what the function was, it might’ve been from the shape of the amino acid. I had the interpretation that it represented something else because amino acids gave me the image of sphere-shaped models. This connects with my next idea, and it is that if the shape of the amino acids are changed from marshmallows to circle, then it could be easier to understand the model because it can help provide a clearer demonstration of it’s role during translation while having a more accurate appearance of the model’s real look. Another concept that can be added is after the tRNA finishes its role and leaves, there can be a string behind the amino acids to show the peptide bond and how they are connected with one another in a chain, rather than having the image that they are floating in a line.
  2. I think this activity is a great way to show protein synthesis. Models in general help many individuals gain a thorough understanding because it is a hands-on activity and using materials and working with your hands can stimulate your brain. Personally, I find hands on activity to be really helpful because sometimes, it’s hard to learn something new just by reading and listening. Working with an activity helps me explore how I can solve my problems and work more on the outside of the box. Another aspect is that models provide a key visual of what the topic is about, giving a visual idea of what protein synthesis is about to the audience. In addition, it is much easier to understand compared to reading an article, or a page because models produce evidence of what you are explaining and shows the process of what you are performing. To add on, the different colors for each model helped my learning a lot as well, since it assisted me in remembering which model represents which RNA. (For example, the green T shaped paper model represented the tRNA.)

 

Resources used:

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