Category: Grade 11

DNA Replication and Protein Syntesis modelling

Leah on

DNA Replication and Protein Synthesis Modelling 

Replication: 

 

           DNA strand                                   DNA strand Unzipped  

 

  1. Explain the structure of DNA – use the terms nucleotides, antiparallel strands, and complementary base pairing.

DNA, or deoxyribonucleic acid, is a double-stranded molecule that stores genetic information in all living organisms. Its structure consists of repeating units called nucleotides, which are composed of a sugar molecule, a phosphate group, and a nitrogenous base. 

The sugar molecule in DNA is called deoxyribose. The phosphate group is attached to the 5′ carbon of the sugar molecule, while the nitrogenous base is attached to the 1′ carbon. 

The four nitrogenous bases in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T). The bases pair up in a specific pattern through hydrogen bonds to form the “rungs” of the DNA ladder. Adenine pairs with thymine, and guanine pairs with cytosine, known as complementary base pairing. 

The two nucleotide strands in DNA are antiparallel or run in opposite directions. One strand runs from 5′ to 3′, while the other runs from 3′ to 5′. The direction of the strands is determined by the orientation of the sugar molecule, which has a free 3′ hydroxyl group on one end and a free 5′ phosphate group on the other end. 

The double helix structure of DNA is formed when the two nucleotide strands twist around each other. The nitrogenous bases form the rungs of the helix, while the sugar-phosphate backbone forms the sides. The hydrogen bonds between the complementary base pairs hold the two strands together, providing stability for the double helix structure. 

 

  1. When does DNA replication occur? 

The DNA process is when the cells synthesize a copy of DNA is the cell’s nucleus. Before the cell divides it must copy or “replicate” its genome so that each daughter cell ends up with its own complete genome. DNA replication occurs during the “S Phase” and is the period in which the cell replicates its genetic content during the cell cycle before mitosis or meiosis and is the product of synthesis or replication. 

 

  1. Firstly, the DNA will unzip, which is when the unwinding of the double helix takes place. Additionally, the two strands of DNA will separate from one another while the hydrogen bonds that were formed between bases are broken. Secondly, complementary base pairing occurs where new nucleotides come into place to pair with the bases of the appropriate template strand of DNA. These new nucleotides are constantly roaming around the nucleoplasm. Finally, adjacent nucleotide bonding occurs where sugar-phosphate bonds are formed between adjacent nucleotides. These nucleotides come from the new strand which is required in order to complete the molecule. Each new strand of DNA has one old strand and one new strand which is called semi-conservative replication. This makes sure that there will be an accurate replication of the parent molecule. In the end, the product of replication by one DNA molecule is two complete double-stranded DNA molecules. Each molecule has one new strand and one old or original strand which had the role of being a template for replication.

The reason that the process occurs differently on the “leading” and “lagging” strands is because of the antiparallel orientation the two chromosomal DNA strands have. The leading strand is replicated in a processive way for the most part while the lagging strand is synthesized in short fragments. 

 

  1. We were given a Strand of DNA and we had to replicate the strand. Once we got to a certain point, we “unzipped” the strand of DNA. Once the DNA was unzipped, we could model the complementary base pairing and attach nucleotide where it belonged creating two strands. The model we made showed a simple understanding of how DNA replicated. This model could be accurate as sometimes incorrectly pairing one nucleotide with another.  

 

Transcription: 

                                                           Transcription from DNA strand to RNA strand          

  1. Describe the process of transcription  

The process of transcription takes place in the nucleus. It uses the DNA to make a template for RNA also known as mRNA molecule. During the transcription process an RNA stand is made to complement a DNA strand. Transcription starts when an RNA polymerase binds to a promoter sequence near the beginning of a gene through helper proteins. Transcription occurs when there is a need for a gene at a certain time or at a certain tissue. When transcription occurs it usually only copies 1 strand of DNA and called a template strand. When in transcription the RNA molecules come together and produce a single stranded messenger RNA (mRNA).  

 

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

It shows how the RNA strand is created from a template strand. And how RNA is it’s own copy of a gene’s DNA sequence. Our model did a great job depicting the accuracy of the process of RNA transcription as the model shows how the ribosomal subunit goes across the template strand making complimentary base parings one by one until 3 of the nucleotides create a stop codon, where the m-RNA creation is stopped. Our model stops the process when we hit the stop codon.  

     

 

Translation: 

 

  1. The process of translation is when a cell uses the genetic information in m-RNA to make proteins. The information m-RNA carries tells cells how to link amino acids together to make proteins. Translation occurs in three steps, initiation, elongation, and termination. During initiation, a ribosome attaches itself to t-RNA which carries methionine they then bind to m-RNA at the start codon AUG. During elongation, the RNA strand gets longer as new nucleotides get added. The final step of translation is termination, where one of the three stop codons will arrive at the A site of the ribosome. No molecules from t-RNA bind to the stop codons so the peptide chain is released into the cytoplasm. 
  2. It was a good model because it showed the fundamental steps how the process of translation occurs and how each amino acid is created based off the mRNA strand that was transcribed from the strand of DNA. The way this was inaccurate was because mRNA translation occurs fast a about amino acids per second whereas we were doing one amino acid per 10 seconds

 

https://sd43bcca-my.sharepoint.com/:w:/r/personal/132-dfedele_sd43_bc_ca/Documents/Translation%20lab.docx?d=wb7c1f00001e04294a8e6e218d27e6408&csf=1&web=1&e=yjmzQd

EPF Forest Walk – Leah

Leah on

On our forest walk with Mr. Cowie we learned and heard a lot about the stories of the first peoples and how they use the outside nature materials for food, medicine and technology.

One of the first things we stumbled upon and had heard a story of was the hemlock and cedar tree which we heard stories about how the creator had chosen who would be the biggest and strongest trees and how their seeds worked.

We also stumbled upon an everyday plant we see which none of us had an idea we could eat. It’s the dandelion weed you can use it for detonation teas and the white liquid inside for medicine.

We also learned about the table berry bush where we learned it can be used for medicine and a lot of elders use it if they feel sore spots of them they smack it on them and use it and it also can be used for food too!!

and next was the bandaid leaf too it can be used for teas and to treat cut. cheese leafs have lines on the back to identify them and come in more a circle and one comes in a more skinny leaf both with the same ridges on the back.

Aboriginal ways of knowing and being:

I think the forest walk was connected learning id connected to land, culture, and spirit because in order to have these plants and trees we honour our land so it can keep bringing us these medicines, foods, and technology. I think it is also connected to the learning from our ancestors, elders, and knowledge because we wouldn’t know these things if it weren’t for them and of course honouring them and the land so it can keep on giving not just us taking and hurting the land without the cause.