DNA Replication
Concluding Questions:
- Explain the structure of DNA – use the terms of nucleotides, antiparallel strands and complimentary base pairing.
DNA’s structure is composed of 4 nucleotides which are the building blocks of DNA. The 4 building blocks are the complimentary base pairs: Adenine (A), Thymine (T), Cytosine (C) and Guanine (G). Adenine pairs with Thymine and Guanine pairs with Cytosine. The base pairs are bonded together by hydrogen bonds. DNA’s shape are 2 antiparallel strands that wind around each other and are in the form of a double helix shape.
- When does DNA replication occur?
DNA replication occurs during S Phase which is the initiation of the cell cycle along with mitosis and cytokinesis.
- Name and describe the 3 steps involved in DNA replication. Why does the process occur differently on the “leading” and “lagging” strands?
As DNA replication commences, the 3 steps involved consist of the opening of the double helix, as that is happening it has separation of the DNA strands, then copying the DNA template. After this process the DNA segment is fully assembled. But the process would occur differently during the leading and lagging strands due to the antiparallel orientation of both chromosomal DNA strands.
- Today’s modelling activity was intended to show the steps involved in DNA replication. What did you do to model the complimentary base pairing and joining of adjacent nucleotides steps? In what ways was this activity well suited to showing this process? In what ways was it inaccurate?
To model the complimentary base pairing, we used the appropriate colors of each base and joined them together with a sketched hydrogen bond with the base they are meant to pair with: (A-T) and (C-G). This activity did a good job showing this process because it showed all the key components. As shown in the picture, it included the base pairings, as long as a hydrogen bond keeping them together, with the sugar group and phosphate group attached to each base. The way it was inaccurate could be how the sugars and phosphates are the same size.
Protein Synthesis
Transcription:
- How is mRNA different than DNA?
mRNA is different because it is responsible for protein synthesis and is a subtype of RNA. DNA is the genetic material of organisms contained in the cell’s nucleus.
| DNA | mRNA |
| Double stranded | Single stranded |
| Deoxyribose sugars | Ribose sugars |
| Use base pairs (A-T) & (C-G) | Use base pairs (A-U) & (C-G) |
- Describe the process of transcription.
DNA exposes its bases through unzipping process, and complementary bases pairs with one strand of DNA to produce RNA. Adjacent RNA nucleotides form sugar and phosphate. DNA rewinds back to its double-helix shape after the RNA strand is released into cytoplasm.
- How did today’s activity do a good job of modelling the process of RNA transcription? In what ways was our model inaccurate?
It did a good job of modelling the process of RNA transcription in terms of showing how RNA codes with one strand of DNA. It clearly illustrated how adenine matches with uracil and guanine matches with cytosine by placing paper on top of another. However, it did a poor job in showing “unzipping” process because it looks like the other half of DNA just disappeared.
Translation:
Initiation:
Elongation:
Termination:
Released Protein:
- How is mRNA different than DNA?
mRNA is different because it is responsible for protein synthesis and is a subtype of RNA. DNA is the genetic material of organisms contained in the cell’s nucleus.
| DNA | mRNA |
| Double stranded | Single stranded |
| Deoxyribose sugars | Ribose sugars |
| Use base pairs (A-T) & (C-G) | Use base pairs (A-U) & (C-G) |
- Describe the process of translation
Translation is the process that uses the information from DNA to build a polypeptide chain, also known as a chain of amino acids. It is mainly divided into 3 subprocesses – initiation, elongation, and termination. First, in the initiation step, the mRNA attaches to the “R” site of the ribosome and initiates translation with its start codon (AUG). Next, in the elongation step, the amino acids are carried by tRNA and connected to form polypeptide chain in the ribosome. Last, in the termination step, a stop codon (UAA, UAG, and UGA), ends elongation stage, which releases a new protein chain.
- How did today’s activity do a good job of modelling the process of RNA translation? In what ways was our model inaccurate?
Today’s activity did a good job of modelling the process of RNA transcription because it gave a great visual representation of initiation, elongation, and termination. It facilitated understanding by developing fine-motor skills and promoting creativity with distinct papers. However, the model was inaccurate in terms of the sizes of the molecules. For example, even though tRNA is much smaller than ribosomes, it looked bigger than ribosomes with paper materials. It was to ease the understanding, but it could have created confusions and give inaccurate information.