Feedback Loops

Blood Sugar Level

High--> beta cells in pancreas secrete insulin into blood stream --> liver and adipose tissue store glucose as glycogen --> blood glucose level returns to homeostasis

Low -->alpha cells in pancreas secrete glucagon --> liver breaks down glycogen into glucose, adipose tissue release glucose --> blood glucose level returns to homeostasis

Metabolism

High --> excessive T3 & T4  inhibit the hypothalamus and anterior pituitary from producing TSH --> no TSH to stimulate the thyroid --> thyroid doesn't produce T3 & T4 --> metabolism returns to normal

Low --> hypothalamus stimulates the anterior pituitary to secrete TSH --> TSH stimulates thyroid to produce T3 & T4 --> metabolism returns to normal

Calcium Level

High --> thyroid produces calcitonin --->calcitonin stimulates the bones to absorb and store calcium, the kidney slows the reabsorbtion of calcium --> calcium level returns to homeostasis

Low --> parathyroid produces PTH --> PTH stimulates the bones to release calcium, the kidney increases reabsorbtion of calcium and activates vitamin D which stimulates the intestines to absorb more calcium --> calcium level returns to homeostasis

36 ATP created through Cellular Respiration

If you are a biology study you should know the equation for cellular respiration is C6H12O6  + 6 O2  → 6 CO2  + 6 H2O + 36 ATP
Just because biology is super amusing and fun, let's count the ATP made in cellular respiration.

• 2 in glycolysis
• 2 in Krebs cycle
• 34 in the electron transport system

But wait that's a total of 38 ATP! But the cellular respiration equation can't be wrong, so where did the extra 2 ATP go?  If we can recall the ETC requires NADH to donate the first 2 electrons, and where do we get these electrons?  2 are from pyruvate oxidation, 6 are from the Krebs cycle, and the last 2 are from glycolysis.  However, we know that the ETC takes place in the mitochondria and 8 of the NADH are already in the mitochondria, except for the 2 NADH from  glycolysis which are still in the cytoplasm.  Thus, to transport the 2 NADH from the cytoplasm into the mitochondria 2 ATP are required.  Therefore, the net equation for cellular respiration still has a total of 36 ATP.

Liver Enzyme Lab Results

Our lab was to test the effect of limiting the substrate (H2O2) on the rate of reaction.  Here are the results:

[H2O2] + [H2O]  (mL/s)       Time (s)                      Gas Collected (mL)                Rate of Reaction (mL/s)

3mL + 0mL                              65                              250                                          3.85

2.5mL + 0.5mL                        27                              250                                          9.26             

2mL + 1mL                              40                              250                                          6.25

1.5mL + 1.5 mL                       47                              250                                          5.32

1mL + 2mL                              60                              250                                          4.17        

0.5mL + 2.5 mL                       20                              250                                          12.5

Second Law of Thermodynamics

Law of Entropy

 During any process, the universe tends toward disorder.  Al spontaneous events act to increase total entropy.

To understand this law, we must first understand entropy.  Entropy is the measure of disorder/randomness/chaos.  Thus, all natural processes increase the total amount of disorder.  So what factors effect entropy, and why does this matter?  Temperature effects entropy, the higher the temperature the higher entropy becomes.  Additionally, chemical bonding lowers entropy.  Naturally things becomes more stable, so the more order the less stable and vice versa.  Hence, entropy can be expressed in a formula if we let:

G = free energy
H = enthalpy (energy contained in a molecule's chemical bond)
S = entropy
T = temperature

G = H - TS

The law of entropy is a universal law that is widely accepted.  Therefore, with this law we are able to predict most natural processes since we know that the universe tends toward disorder.

Science Fair!

Angeline and I have been inspired by the work of Dr. Daniel Durocher and Rongmin Zhao in the protein ubiquitin. Ubiquitin is a protein found in eukaryote cells that signal the protein proteasome to degrade specific proteins.  

Thus our question is how does ubiquitin play a role in cancer, and how can we minimize the effect.  Cancer cells, are cells that are unable to recognize when to stop reproduction.  Thus we believe the malfunction of unbiquitin and proteasome will enhance the oncoproteins, since the proteins will not be properly degraded.
To test our theory we will be injecting different amounts of ubiquitin in tumors to see the effect of ubiquitin.

Independent Variable : Ubiquitin levels
Dependent Variable : number of cancer cells after changing ubiquitin levels
Controlled Variable : cells without additional ubiquitin

Research in ubiquitin and proteasome will help improve the lives of cancer and neurodegenerative patients, since it could lead to better medication and therapy treatments.

Deaf? So What.

The definition of disability according to the Oxford dictionary is:
a physical or mental condition that restricts your movements, senses, or activities.  A disadvantage or handicap.

In those terms having an allergy to peanuts, not being talented inclined in soccer or even having long hair could be classified as a disability.  So then what is a disability? Are the classic examples, such as being deaf,  really a disability?  Not according to Heather's dad, being deaf has opened him up to the society of deaf people to which he would have never been accepted had he not been deaf. In "Sound & Fury" Heather, a young girl of 7, desperately wanted a cochlear implant to communicate with the hearing society.  Her parents, both being deaf as well, were offended by the very idea.  They felt as if their daughter was betraying them and Heather's father immediately rejected the idea.  Five years later Heather finally got her wish and was given the ability to hear, there are many controversies about whether or not this is in Heather's best interest.  In my opinion I think having a cochlear implant is a benefit for Heather because she will still carry her deaf knowledge (ASL) and now she will have the advantage of enjoying verbal communication, music and other benefits of hearing.  In modern times there are numerous help groups that will help you improve your language even if your parents aren't able too, so there's no problem there with her parents.  If in time Heather decides she would rather not hear a single word she could simply stop using her cochlear implant and live life as she recognizes it.  This being said I think Heather has the best of both worlds, meaning that being deaf is not a disability it is simply a different form of life.

Another issue with the deaf society was acknowledged in "Deaf by Design" publish in Nature.  The issue was whether of not deaf people should have the right to abort their fetus.  It's quite understandable why a deaf couple would prefer to have a deaf child; easier forms of communication, better bonds between the family and etc.  However, how far  are you willing to take that?  There has been controversy over the fact that some deaf couples would like to genetically screen their child to ensure that they are deaf as well.  However how is that really different from a designer child to have an IQ of 160 or to have blonde hair and blue eyes?  When you get down to it, there is no difference at all.  There is an even bigger controversy about whether or not deaf parents should be allowed to abort their child  if that child isn't deaf.  However when you think about it, it's no different than a hearing couple aborting a deaf child.  So why discriminate the deaf?  This brings us back to the question of what is a disability because clearly the definition of disability for the dead society is different from the hearing society.  Thus the definition provided by the Oxford dictionary does not do the word justice, therefore I came up with my definition.

Disability : The act of letting society outcast you.

The Natural Ways of Preventing Mutation

1. Semi-Conservative DNA replication

The 3 models of DNA replication that Watson and Crick presented in Nature were conservative, semi-conservative and dispersive.  The conservative model was that the daughter DNA will model itself after the parent DNA, while the parent DNA stays intact.  Watson and Crick hypothesized that throughout each replication the daughter DNA will become less precise and clean each time.  The dispersive method is that random parts of the parent DNA are split into two strands while nucleotides fill in the gaps for the daughter DNA.  This model however induces mutation because the method would require us to break the DNA.  Thus the semi-conservative method was choose, this model is where the parent DNA splits directly down the middle while nucleotides used half of the parent strand to form the daughter strands.  This model was later proven by Meselson-Stahl.

2. Bubble Replication

We know DNA replicates itself with the semi-conservative method, however if helicase were to unzip the entire DNA double helix before polymerase 3 started replication, there would be an extremely high risk of mutation.  Thus multiple helicases start to unzip the DNA simultaneously at different positions, while multiple polymerase 3 attaches immediately and begins replication, allowing little chance for mutation to occure.

3. mRNA caps
During the production of proteins the DNA is copied into pre mRNA, this transcription is a direct pairing from the DNA gene.  Once we have our pre mRNA the ends of the strand are at a risk of mutation, thus we naturally protect these ends with caps.  The 5' end is protected with what is known as a G-cap, where an extra guanine nucleotide is added.  The 3' end is protected with a poly A polymerase tail, which is simply a chain of adenine nucleotides.  Theses caps will help prevent any mutation on the pre mRNA because any mutation will be prevented or it will occur on the caps.

4. Introns
After capping our pre mRNA we also need to protect not only our ends but the middle too.  The pre mRNA is divided into two types, exons (important codes) and introns (unimportant codes).  If mutation does occur during the pre mRNA phase, there is a lower probability that the mutations will occur at the exons, if all the exons are spaced with introns.  Since the introns are not important to the production of proteins, if a mutation occurs there it will be a silent mutation.

5.  Wobble Position
After the pre mRNA becomes mRNA we need to translate the mRNA into a polypeptide chain.  The mRNA is grouped into triplets (codons) and each codon codes for a specific amino acid.  However most codons code for the same amino acids, for example AAA and AAG both code for lysine.  Thus if there is a mutation in AAA and it becomes AAG there will be no difference to the overall polypeptide chain.  The third nucletide in a codon is called the wobble position because its allows for mutations to occur without damaging our protein production.