Category: A&P12

Agar cubes

The most effective sized cube that maximized diffusion was the 1cm cube.
It was the most effective at maximizing diffusion because the sodium hydroxide didn’t have as much surface area that it had to travel through. Important factors that affect how materials diffuse into cells is cell size because as a cell grows, there is less membrane for the substance to diffuse through which means that the centre of cell will not get the substances needed. It also means that diffusion is less efficient, and the cell process slows down and the cell stop growing. Another factor is an organism being multicellular because the organism has evolved features such as gas exchange organs, circulatory system.
Cells grow not to be very large because it would increase the volume size which would cause the SA:V ratio to be smaller. If the ratio was smaller, it would mean that diffusion would be harder and less effective to maximize diffusion for nutrients and resources to pass through cell membrane.
Cube C would be the most effective at maximizing diffusion because it has more surface area and less volume that resources and nutrients must travel through. Its smaller size will allow for everything inside the middle of the cell to be affected.
Our bodies adapt surface area to volume to help exchange gases by having long and thing nerve cells along with folds in the membrane.
Certain cells can’t get to be the size of a small fish because the SA:V ratio will become smaller which will mean that the diffusion process will be less effective. The cell wouldn’t be able to function properly because it wouldn’t be able to absorb all of the materials that are trying to penetrate it
The advantages of a large organism being multicellular is that they have a faster process of diffusion which means that it can have more functions at once.

Protein + translation

mRNA is different from DNA because DNA is a double-stranded which takes the form of a double helix while mRNA is single-stranded. DNA is a nucleic acid while mRNA is a ribonucleic acid. DNA is the basic genetic material and is made up of three things: a phosphate, a sugar, and a nitrogenous base. mRNA is one type of RNA. It is made up of ribonucleotides and occurs in the nucleus by transcription using DNA. DNA and mRNA contain three of the same bases but have one different from each other, DNA contains thymine and mRNA contains uracil.

Transcription is done by an enzyme called polymerase. Transcription is the process of the information on 1 DNA gene is copied onto a strand of mRNA. Transcription happens in three phases. The first is unwinding the second is complementary base pairing then the third is separation from DNA.

Today’s activity was helpful because it showed each step that DNA transcription had to do and how it had to do it. It was also helpful because it showed us how RNA and DNA had their own special base and how their structures were different. The model was inaccurate in the way that it didn’t show how transcription was just fragments of DNA. The activity made it seem as if it was the entire double helix. It was also inaccurate in the way that RNA is smaller than DNA but, in the activity, they were shown as the same size.

Initiation is when RNA polymerase binds to a fragment of DNA near the beginning of a gene. When it is bound together, PNA polymerase separates the DNA strands which provides the structure of a single stand that is needed for transcription. Elongation is when the DNA is read base by base. It is when polymerase builds a molecule of RNA out of nucleotides that are complementary to each other. The strand that has been transcripted carries the same information as the original DNA strand but uses uracil instead of thymine. Termination is a sequence that signals that the RNA transcript has been completed. It causes the transcripted DNA to be released from the polymerase enzyme.


Today’s activity did a good job of modelling the translation process because it helped us understand translation more clearly by having us do it ourselves. It also helped to show us the way that each separate step worked. It was a bit confusing with the instructions at some parts because we couldn’t tell what each separate piece of paper was supposed to be for.

DNA and Protein synthesis

DNA is a large polymer that is made up of multiple nucleotide monomers. Nucleotides are made up of 3 different components which include a sugar, a phosphate group and a nitrogenous base. It contains 2 backbones that are made up of bonded sugar-phosphate portions of adjacent nucleotides. The two complimentary strands that DNA is made up of, run antiparallel to each other which means they run opposite directions. Each strand has a 5’ end and a 3’ end. The two strands being antiparallel means that complementary base pairing can happen which allows the two DNA strands to be held together. Bases always bond with the same partner (Adenine and Thymine, Guanine and Cytosine)

This activity helped model the structure of DNA because it showed how complementary base pairing works and how new strands of DNA can form. It also helped to show the shape of DNA. To help improve the accuracy of the model we could have used different objects to help show different bonds and where they happen.

DNA replication is an essential part of cell division and the growth of all organisms. It uses strands of DNA to create new strands. It occurs before new cells are formed because it requires genetic information for it to split.

The 3 steps that are involved in DNA replication are: Unwinding, complementary base pairing, and joining. Unwinding is when the DNA helix unwinds and the H-bonds between base pairs break. The DNA helicase enzyme is what causes DNA to unwind. Complementary base pairing is when nucleotides move into place to form and H-bond with their “partner” on another strand. Polymerase is what causes complementary base pairing. Joining is when nucleotides on a new strand form covalent bonds with their “partner”. The leading strand is continuous as DNA continues to unzip and the lagging strand has fragments form as DNA unzips. DNA ligase is what glues fragments together. A leading strand is synthesized in the 5’ to 3’ direction while a lagging strand is synthesized in the 3’ to 5’ direction.

To model the complementary base pairing, we detached some of the pairings from each other and then used different coloured playdough to show what helicase, polymerase, and ligase do. The model was helpful in showing what the different enzymes did, but it was not helpful in the way that our model kept falling apart and sometimes the instructions were not clear so we didn’t know what we were supposed to do some of the time.