Author: sierrao-2014

Agar Cubes Lab

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1.       n terms of maximizing diffusion, what was the most effective cube you tested?
 The 1cm^3 cube was the most efficient at maximizing diffusion.

2.       Why was size most effective at maximizing diffusion? What are the important factors that affect how materials diffuse into cells or tissues?
   The ratio of the surface area to volume was 6:1, meaning that this cube had 6 times the space to absorb the solution than needed to be coloured.

3.       If a large surface area is helpful to cells, why do cells not grow very large?
 Cells growing larger would increase the surface area, but it would also increase the volume that the surface area needs to absorb nutrients for and would thus be ineffective.

4.       You have 3 cubes, A, B and C. They have surface-volume ratios of 3:1, 5:2 and 4;1 respectively. Which of these cubes is going to be the most effective at maximizing diffusion, how do you know this?
Cube C will be the most effective at maximizing diffusion, as it has the greatest ratio of surface area to volume. It has more surface area that is able to absorb nutrients for the comparatively small volume.

5.       How does your body adapt surface area to volume ratios to help exchange gases?
 Smaller cells and organelles have evolved over time to be able to efficiently absorb and exchange gases to power themselves and the cell they belong to.

6.       Why can’t certain cells, like bacteria, get to be the size of a small fish?
Because the ratio of surface area to volume would be unsustainable and not enough nutrients would be able to be absorbed to power the cell.

7.       What are the advantages of large organisms being multicellular?
 Have many small cells better allows each to be able to function properly and to be able to exchange nutrients and gases with one another with minimal effort, as well as for nutrients to be absorbed most efficiently.

 

DNA and Protein Synthesis

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  1. Explain the structure of DNA – use the terms nucleotides, antiparallel strands, and complementary base pairings. DNA belongs to the group of molecules called nucleotides, which all contain a sugar, nitrogenous base and a phosphate group.
  2. 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. We used blue pipe cleaners with black beads to model the sugar and phosphate groups that make up the DNA backbone, as well as white pipe cleaners with coloured beads to represent the four nitrogenous bases. Each white pipe cleaner was hooked to the one across from it that held its complementary base pair; the hooks representing the hydrogen bonds. Reducing the length of the white pipe cleaner could make the model more accurate, as in reality there is nothing separating the nitrogenous bases from the backbone of the molecule.
  3. When does DNA replication occur? DNA replication occurs during mitosis. To create a clone of the cell it is dividing from, the nucleus must also contain an exact replica of the chromosomes and DNA in the previous cell and every other cell in the body for it to do its job properly.
  4. Name and describe the 3 steps involved in DNA replication. Why does this process occur differently on the ‘leading’ and ‘lagging’ strands? 1. Unwinding and ‘unzipping,’ this process is completed by the helicase, which runs down the strand of conjoined DNA and breaks the hydrogen bonds between the complementary base pairs, effectively creating two parent strands. 2. Complementary base pairing. Completed by the polymerase, it follows the helicase down the strand to pair the bases exposed on the parent strand. Because the strands are anti-parallel, the polymerases must travel in opposite directions. While one may be able to follow the helicase, the other must read chunks at a time in the opposite direction and backtrack to return to the helicase. 3. Joining of adjacent nucleotides. The ligase then follows the polymerase down the strand and joins the fragments together to create a fully formed backbone and newly replicated DNA molecule.
  5. The model today wasn’t a great fit for the process we were exploring. What did you do to model the complementary base pairing 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? The model was able to show the general placement of each part of the process but was not able to fully replicate the bonds between the nitrogenous bases and the backbone of the molecule.
  6. How is mRNA different from DNA? Besides having their own unique nitrogenous base, (uracil and thymine) DNA and mRNA are structurally different as well. While DNA can be up to 85 million base pairs long, mRNA is usually only 1000. Also, while DNA has two backbones made from the sugar deoxyribose, mRNA only has one, made from ribose.
  7. Describe the process of transcription. DNA unwinds itself from the chromosome it was contained in and is unzipped. An RNA polymerase reads the ‘sense’ strand and pairs the bases with their complementary RNA counterparts. Once complete, the newly formed mRNA molecule breaks off of the DNA, which re-zips itself and rewinds itself back into the chromosome it came from.
  8. How did today’s activity do a good job modelling the process of transcription? In what ways was our model inaccurate. The model did a good job showing the general structure of the molecules involved in the process but again did not properly show the proportions to which everything is actually to scale.

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Lit. Circles Book Review: Red Rising

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The book started off with a very powerful beginning that provides inspiration for the main character throughout the rest of the book. The story has very quickly progressed, with Darrow having about 5 major setting changes so far. Darrow has come in conflict with his own identity on a few occasions and is currently conflicted over whether or not he should tell Cassius the truth about his brother. So far the book has had a very similar theme and plot line to The Hunger Games, with Darrow having been born and raised in poverty and losing a loved one so young. He moves forward throughout the book in the name of Eo and her dream, as Katniss did for her sister. He gets a makeover and enters the ‘Institute’, and the war games that also bear resemblance to the hunger games that Katniss must compete in. Darrow, like Katniss, feels that he doesn’t belong to the golds and has to feign relationships to get head in the game. If I had not read The Hunger Games before reading Red Rising, I would think that Red Rising is an incredible book and would definitely recommend it to everybody. The book is overall entertaining and would probably be a lot more so if the particular genre if belongs to were a little more diverse.

What is the best method for Solving Quadratic equations?

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A quadratic equation is an equation that can be written in the form ax^2 + bx + c = 0, where a is not equal to zero.

The fastest way to solve a quadratic equation is through factoring, which involves inspection of the equation. If, upon inspection, the equation does not factor, you can try adding a value to both sides to complete the square. The quadratic formula is essentailly an already reduced version of competing the square. In my opinion the quadratic formula is consistently the most reliable to solve, but, when possible, I would like to factor first.

What Darwin Never Knew

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Charles Darwin’s findings in South America and the Galapagos islands promted him to think of what has been called the “Greastest Idea of all time”; The theory of evolution. In South America, Darwin found the fossils of a giant sloth, which he was able to trace back to modern, smaller size sloths that were still alive. This was the evidence that put his train of thought in motion. Later, he travelled to the Galapagos islands and made many observations there, as well as collecting samples of different animals, most notably the Galapagos finches. However, Darwin did not fully complete his theory until he returned home. There, he studied his findings and was intruiged by the finches. He noted all the similarities and differences between the finches, such as their different sizes and beaks. Darwin arrived at his theory after studying embryos of different species and noted that they all started out very similar, and that the developmental process was where they began to slowly differentiate. This sparked an idea of a common ancestor. For example, a single species of finch could have journeyed to the Galapagos and, over time, have evolved into many different species. Darwin’s theory was absolutely correct, however, he had no idea how it happened.

What Darwin never knew about was DNA. A species gradually changes over time through random genetic mutations, which can give different characteristics to a member of a species. Should this mutation be beneficial to said member, chances are that they will live long enough to reproduce, and thus pass on the mutation to their offspring. Keeping a specific group of a species isolated long enough, (isolating the gene pool), will broaden the chances of a new species forming, since the two seperated groups will keep different mutations contained within their individual offspring. Given enough time, the single species could easily become two. This is how a single common ancestor could’ve, over many years, become the millions of species that we have on our planet today. In conclusion, DNA was the missing link to Darwin’s theory of evolution, the key to all life on earth.