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Agar Cube Lab

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  1. The most effective size cube for maximizing diffusion was the 1cm³ cube
  2. It was most effective at maximizing diffusion because since the cube was so small the surface area to volume ratio was the smallest of the three, so then the hydroxide was able to penetrate all the surfaces and go deeper into the cube quicker than the others. Important factors that effect how materials diffuse are the permeability of the cells membrane, the mobility of the material, the concentration of the material, and the temperature.
  3. Cells don’t grow to be very large in size because although a large surface area is best, the larger the cell the more volume it has so then with the more volume it has the longer it would take to be able to diffuse fully.
  4. Cube C with the surface to volume ratio 4:1 would be more effective at maximizing diffusion because since it has more surface area than volume, particles can travel into the centre of the cell much easier.
  5. Our body contains small cells which adapt surface area to volume ratios in order to exchange gases easily. By having a moderately large surface area compared to the volume, the gas is able to diffuse throughout the entire cell very easily. If the cells were to grow in size, the surface area to volume ratio would decrease meaning that the rate of gas exchange would decrease also.
  6. Bacteria is unable to grow into the size of a small fish because if a cell were to grow too big, the surface area to volume ratio would decrease meaning that diffusion percent would decrease also and gas exchange would be hard to carry out. Eventually, the bacteria would not be able to sustain itself anymore and would die.
  7. The advantages of a large organism being multicellular is that the organism can grow larger while the cells stay small so then the cells are able to obtain the materials they need to survive more easily. It also allows for having different types of cells for different functions. Being multicellular is also an advantage because if some of your cells die, they can be replenished with little to no harm done to you (usually) instead of you shutting down and dying like bacteria would.

DNA and Protein Synthesis Part 4

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  1. Translation occurs in 3 steps; initiation, elongation, and termination. During initiation, mRNA binds to a ribosome subunit which then binds to another ribosome subunit. The ribosome subunit then scans the mRNA for a start sequence which begins translation. Next, during elongation, the ribosome subunit holds the mRNA in place while complementary tRNA is attached to the binding sites. mRNA contains a 3 letter code called a codon while the tRNA contains a complementary code called an anti codon. Each codon is specific to one of the 20 amino acids. tRNA binds to the “P” site, while another tRNA binds to the “A” site. This binding causes change which results in the amino acid letting go of the tRNA and binding to the neighbouring amino acid. Then, the empty tRNA leaves the ribosome as it moves along the mRNA. As the ribosome moves along, the 2nd tRNA goes to the “P” site and new tRNA binds to mRNA at the “A” site. Finally, termination occurs which is when the mRNA reads a stop codon which does not have a matching tRNA. This codon puts an end to the elongation cycle, and since no new amino acid is added to the chain, the ribosome dissociates into its 2 subunits and the polypeptide is released.
  2. The model did a good job of showing every step clearly and what happened during those steps. There was nothing majorly inaccurate about the model.

DNA and Protein Synthesis Part 3

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  1. mRNA is different than DNA in many ways. For example, mRNA is a single sided strand where DNA is double strand. Also, mRNA is much smaller in size than DNA since it has to be small enough to move in and out of the nucleus. By being able to move around, the DNA can stay in the nucleus while the mRNA copies the DNA and carries it to the ribosomes in order to carry out transcription.
  2. The process of transcription can be broken into 3 phases; unwinding and unzipping of DNA, complementary base pairing with DNA, and separation from DNA. In the unwinding and unzipping of DNA, RNA polymerase untwists the DNA alpha helix shape. Then, the mRNA nucleotides are paired up with the complementary nucleotides from the DNA strand. Finally, once the mRNA has copied the DNA, it leaves the nucleus as the DNA returns to its original form without any harm done to it.
  3. By modelling this, it was easy to see the first two steps of transcription without any problem. It was clear what was happening and the role of the RNA polymerase. However, it was difficult to model how the mRNA copies the DNA and then leaves the nucleus. It also was an inaccurate representation of the size difference between mRNA and DNA.

DNA and Protein Synthesis Part 2

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  1. DNA replication occurs before mitosis because the cell realizes that it is becoming too big so it has to divide in order to keep doing its function. If the cell were to grow any bigger, it would not be able to do it’s job, so it divides into two daughter cells.
  2. The 3 steps involved in DNA replication are unwinding and unzipping, complementary base pairing, and the joining of opposite nucleotides. In the first step (unwinding and unzipping) a DNA helicase breaks the Hydrogen bonds which hold the nucleotides together. Once the bonds are broken by the helicase, the DNA structure unwinds. Then in complementary base pairing, DNA polymerase match the opposite nucleotides together; Adenine bonds with Thymine and Guanine bonds with Cytosine. Finally, in the final step, (joining of nucleotides) DNA ligase put these nucleotides together and creates two new strands of DNA. The 3 steps are different on the “leading” and “lagging” strands because the DNA polymerase can only read the DNA strand from 3′ to 5′ which means the lagging strand has to be read backwards. The “leading” strand is the one with the extra sugar at the beginning.
  3. By modelling these, we were able to represent how the hydrogen bonds break apart and the steps that follow. By using different candies, we were able to represent the polymerase, helicase, and ligase and there job pretty accurately. However, it was hard to tell which strand was the leading and lagging one based on the model. Also, since we used blue pipe cleaner for all the DNA strand backbones, you never got a clear picture of which one was the parent DNA strand vs the daughter strand.

DNA and Protein Synthesis Part 1

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  1. DNA has an alpha helix shape which consists of nucleotides. Nucleotides are made of pentose, phosphate, and a nitrogenous base. They have 2 types of bases; purines and pyrimidines. Pyrimidines consist of a single ring structure with thymine and cytosine while purines have a double ring structure with adenine and guanine. Since there is complementary base pairing between the nucleotides adenine and thymine as well as guanine and cytosine, they bond together to create the alpha helix shape that DNA has. DNA also consists of antiparallel strands meaning that the sugar and phosphate are aligned in opposite directions on each backbone of the DNA helix.
  2. The activity helps model the structure as it clearly shows the nucleotides and how they bond together to create the double helix shape. However, it is hard to see that the backbone contains sugar as well as phosphate. Next time we should add a different colour bead for sugar and also maybe use a different colour bead for the phosphate so it can stand out better from the blue pipe cleaner.

Neuron and Synapse Function

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Neurons are cells that transmit information to other nerve cells, muscle, or gland cells. There are three types of neurons; motor neurons, sensory neurons, and interneurons. Each neuron is composed of a cell body, dendrites, and an axon. Some neurons however have myelin sheath. The cell body supports the life of the neuron, while the axon transmits and carries signals to other neurons. The dendrites are then there to receive those signals. The myelin sheath function is to improve the safety and speed of the neural impulses along the axon. It serves as an electrical insulator that prevents the dispersion of the impulses into other structures.The only type of neuron that has myelin sheath is the sensory neuron.

The process in which neurons send electrical pulses to communicate is called action potential. The neuron sends an electrical charge through depolarization and repolarization. When the axon is at resting potential, it has a negative charge inside. Depolarization is when the channels in the axon’s membrane open up and let in sodium ions, changing the charge of the axon to positive. In repolarization, potassium ions exit the the axon’s membrane which results in it having a negative charge again. The process continues all the way through the axon which carries the charge through the neuron.

The synapse has three parts to it. There is the presynaptic membrane, the postsynaptic membrane, and synaptic gap. Once the action potential has reached the axon terminal, it connects to the presynaptic membrane which then releases neurotransmitters into the synaptic gap between the nerve cells. The neurotransmitters then bind onto the postsynaptic membrane and respond in either a inhibitory or excitatory way. If it is excitatory, then the neuron receiving the action potential will continue to send it along. However, if it is inhibitory then the neuron will stop sending the action potential.

A Place at the Table Video Response

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  1. Throughout the movie, many food insecurities were mentioned. Some of the most notable ones was when people in need got turned away from food stamps because they were over the limit by a couple dollars, or when they did not make enough money to feed themselves and their kids. Many of these individuals coped with their situations by asking friends for food, going to churches for meals, or trying to make the limited food that they had stretch for the weeks to come. Some of these people were successful for a short period of time, but in the long run it did not help. There is only so much people can do to help, and there is only so far food will last even if you try and stretch it. They might have been good for breakfast that day, but what about breakfast the next day or even the following week.
  2. Certain people in our country are more at risk than others due to demographics. Low income, elderly, single parents, and children are mostly at risk. Farmers, “Mom and Pop” shops, and people living in food deserts are also at risk because little famers don’t get enough support like the big companies do, so they are forced to close down or raise their prices just to make a profit. The big farming companies subsidized processed food like wheat and corn instead of fruit and vegetables since it is cheaper and the quantity being produced is higher. Little “mom and pop” shops do not get supplied fruit and vegetables due to the big company trucks carrying the products not stopping in their towns. The truck does not want to go down side roads to get to a little town and have to pay for that detour gas when they can just go to big markets like Walmart. People who live in little towns that do not get access to fresh fruits and vegetables are living in food deserts and are at risk because they do not get the right nutrition and balance of diet that they need. The Great Depression has influenced the agriculture business to this day.
  3. After watching this video it made me realize how lucky I am for the food that I am supplied with everyday. Seeing all those people and their struggles made me sad and kind of outraged at their government for turning away people for food stamps because they were 2 dollars over the annual income amount to qualify for food stamps. The government said they would help the children who are hungry by providing school lunches, but the money for that came out of food stamps. They just cut food stamps and gave it to the kids in need, yet the upper class would not let any money be cut from them. Watching this video personally made me very emotionally upset and I was shocked by how many people were truly hungry. I knew that hunger was a big issue, but I did not think it was so predominant in a country with such a big food supply. It was shocking and sad to see how many people are hungry but did not receive help in fixing this issue.
  4. In order to make a difference with this situation, I’d volunteer at food banks and try and raise my own money to support the people in need. I would support local farmers instead of big companies so that they can supply the town with fresh fruit and vegetables needed to maintain proper nutrition. I’d try and raise money and give it directly to families in need to buy proper food to support themselves, and I’d raise awareness about hunger. A lot of people are hungry but do not talk about it, so we could be their voice and speak out for them. Lend a helping hand and maybe buy more food than you need and give the extra bag to someone who is hungry and needs to eat.