Explain the structure of DNA – use the terms nucleotides, antiparallel strands, and complimentary base pairing.
Nucleotides are made up of a ribose, a phosphate, and a nitrogen base. In our photo, these are represented by a bit of blue pipecleaner, the coloured beads, and the black beads. These three things, combined, make a nucleotide.
DNA has two anti parallel strands, meaning that the strands are read reverse of each other.
Complimentary base pairing means that each nitrogenous base pairs with one other base in DNA. These are represented by the coloured beads, and that T only pairs with A, and C only pairs with G.
How does this activity help model the structure of DNA? What changes could we make to improve the accuracy of this model? Be detailed and constructive.
It gives a visual representation of what DNA looks like. It also helps us to see how the bonds work and remember that certain nitrogenous bases only pair with others. In order to improve the activity, we could
When does DNA replication occur?
Occurs when cells divide. The first photo shows DNA helicase (fuzzy peach) “unzipping” the DNA, while DNA polymerase H bonds nucleotides on the lagging strand
The second photo also has helicase upzipping DNA while polymerase H bonds on the leading strand
The third photo shows ligase bonding a sugar phosphate backbone on the daughter strand
Name and describe the 3 steps involved in DNA replication. Why does the process occur differently on the “leading” and “lagging” strands?
Described above. These processes occur differently for leading and lagging strands because DNA must be read in a certain direction, from 3′ to 5′. So, polymerase can read the leading strand, as it is oriented 3′ to 5′, but it must do chunks of the lagging strand, by fragments.
In the above photo, the bunny is oriented in the opposite direction that the helicase is unzipping, this is because it must read toward 5′. It will reach to where it has already bonded, and then move up to where the unzipping is and begin to work backwards, again.
The model today wasn’t a great fit for the process we were exploring. What did you do to model the complimentary base pairing and joining of adjacent nucleotides steps of DNA replication. In what ways was this activity well suited to showing this process? In what ways was it inaccurate?
To model complimentary base pairing, we made the nucleotides with beads and small white pipcleaners, and then attached them to their complimentary nuclelotide with a hook, representing the H bonds between complementary bases. Adjacent models nucleotides were attached by all being attached to a common backbone.
This was well suited because it was visually very similar to the way DNA looks
This was inaccurate in that the nucleotides attached to the backbone, which is not exactly how DNA works. In DNA, the ends of DNA (sugar/phosphate) are attached to nucleotides, which bond with neighboring nucleotides. The base and the backbone it is near are one single entity, not separate.
mRNA is fundamentally different from DNA in that it is a single strand, rather than two. It is also different because where in DNA one might find Thymine, mRNA would have Uracil.
Transcription is the process of copying a DNA gene and sending it to a ribosome to create protein. In transcription, the DNA unwinds, and then RNA polymerase unzips a section, then facilitates the creation of a strand of mRNA.
This was good because it showed how a strand is created using the instructions of DNA. It was not a good representation because a section of DNA unwinds when RNA is created, but when we unwinded it to make mRNA, we had to completely take the two backbones apart.
Describe the process of translation: initiation, elongation, and termination
Initiation starts when the ribosome attaches itself to the subunit, and then the two subunits attach to each other. Then the ribosome searches along the mRNA for AUG. Elongation is when proteins are brought to the A or P site and attach at the P site, to each other. Termination is when the ribosome reads a “stop” codon and releases the amino acid string.
How did today’s activity do a good job of modelling the process of translation? In what ways was our model inaccurate?
The activity, out of all the ones we did, was probably the most accurate, as it showed all the steps as they happened. Nothing was particularly inaccurate about it.
One thought on “DNA and Protein Synthesis”
This blog post was very well written, and really helps the reader to understand DNA and RNA. The pictures were chosen very well to suit the explanations. Although your explanations were well thought out, the first part was missing an answer as to how we could have made the activity better. Overall good work, and very informative!
Nucleotides are made up of a ribose, a phosphate, and a nitrogen base. In our photo, these are represented by a bit of blue pipecleaner, the coloured beads, and the black beads. These three things, combined, make a nucleotide.
This blog post was very well written, and really helps the reader to understand DNA and RNA. The pictures were chosen very well to suit the explanations. Although your explanations were well thought out, the first part was missing an answer as to how we could have made the activity better. Overall good work, and very informative!