Writing in Biology

Vitamin D is indicated to be lacking in my diet, for the target of 15 micrograms is not met for I only consume about 3 micrograms on average. Not getting enough vitamin D can be dangerous for it plays the role of modulating cell growth, neuromuscular and immune functions, absorption of calcium, therefore, contributing to bone growth. Deficiency not very uncommon because vitamin D is naturally not present in many foods, making it more important that we are aware of our intakes8. Given that we are entering the colder months it also is more challenging to obtain vitamin D from the sun, therefore it must be done by selecting proper foods. As mentioned before, fat-soluble vitamins are more likely to cause toxicity for it is stored in the body, therefore monitoring the intake of this vitamin is extremely important. In most extreme cases toxicity may raise blood levels of calcium, in turn leading to damage to the heart, blood vessels and kidneys8. Some of the best sources of Vitamin D are fatty fish, including salmon and tuna, both of which are foods I enjoy and will add to my diet in greater amounts to make up for the lack of Vitamin D in my diet. Beef liver, cheese, and egg yolks also contain some amounts of vitamin D.

The first stage to oxidative phosophorlation is called the Electron transport chain (ETC). During this stage, reduced electron carriers in the form of NADH and FADH2 enter the complexes of ETC. Complex 1 strips NADH of its electrons and pumps them to coenzyme Q. In addition to this complex 1 will pump protons to the intermembrane area. Complex 2 strips FADH2 of its electrons and donates them to coenzyme Q as well. However, Complex 2 does NOT pump protons. Coenzyme Q will then donate the electrons it recieves to complex 3, which pumps more protons to the intermembrane space. In turn, complex 3 donates electrons to Cytochrome C, a water soluable protein which can move around the intermembrane space. Cytochrome C transports electrons to Complex 4. Complex 4 pumps protons to the intermembrane space as well, and donates its electrons to the final electron reciever, oxygen. This process produces H2O. It is importan for these complex to pump protons to the intermembrane space to set up a proton gradient. The proton gradient is used to power the last part of oxidative phosophorylation, ATP synathse. Protons from the intermembrane space essentially store energy and release it by moving through the gradiant and back into the mitochondrial matrix through ATP synthase. For every 3 protons which pass through the protein, 1 ATP is created.

The cycohexanol was reacted using heat and a strong acid and the alkene was obtained in 57% yield. The distillate range was 68°C-70°C, suggesting that the compound was relatively impure since the range was lower than expected. When either bromine or KMnO4 were added to the cyclohexene product it did not mix so it remained clear, but in the cyclohexane product they did mix and turned a reddish brown color in the case of the bromine and a purplish color in the case of the KMnO4, which were the expected results. The Gas chromatography suggested that the mixture was around 76% cyclohexene, which suggested that the actual yield was about 0.014 mol, hence the theoretical yield of 57%. The resulting substance was relatively impure.

Glycolysis and gluconeogenesis are two glycolytic pathways involving the synthesis and degradation of pyruvate from glucose. Although these reactions look like the opposite of each other, gluconeogenesis actually bypasses three pathways involved in glycolysis. Three irreversible reactions including the enzymes hexokinase, PFK-1, and pyruvate kinase must be bypassed due to their change in free energy. The changes in free energy for these pathways are -33 kJ/mol, -22.2 kJ/mol and -33.2 kJ/mol respectively. When a reaction has a change in free energy that is 0 or close to 0, it is easy to reverse and therefore is used in the process of gluconeogenesis. Being that the changes in free energy for these three pathways in glycolysis have such high negative values, gluconeogenesis must find a way around these reactions in order to degrade pyruvate. Therefore, the reaction uses different enzymes for these three pathways in order to complete the degradation of pyruvate when necessary.

. After letting the participant observe the second card, he went down the line of 7 staged people and asked them which line on the card matched the original card. They told their answer out loud for the rest of the participants to hear. Each participant said the obviously correct answer, including the newest participant. He then repeated this task 3 times. However, on the third trial, the 7 staged participants said the same obviously incorrect answer. This was to test whether the newest participant would say the correct answer, or follow their peers and say the wrong answer despite it being obviously incorrect. As a result, Asch found that at 75% of the participants said the incorrect answer with the rest of the group at least one time throughout the trials. This experiments proved that people can depend on conformity in group settings, seeing as the participant said the incorrect answer when the rest of the 7 group members said it.  It is interesting to see how someone’s answer can be so greatly affected by their group members even when the correct answer is obvious. When the other participants said the incorrect answer, the participant must have questioned their own thoughts or were too nervous to go against the norm. 

Conformity refers to the idea of humans following the actions or behaviors of a group of people that they familiarize themselves with. This concept is most relevant to young teenagers who are trying to figure out their identity or personality as they may be prone to following the actions of their peers in order to fit in. These conforming actions may disagree with one’s true morals or beliefs due to the fear of being different. Solomon Asch’s experiments with conformity help to determine how powerful the idea of conformity is on personality traits in adolescents. His experiments focused on perceptual conformity, a type of conformity that deals with the perception of senses such as taste, touch, and smell. During one of his experiments he had a volunteer sit down next to 7 other staged participants. He then gave each participant the same card and ask them to remember the length of the line on the given card. After he let the participants observe the first card, he took it away and gave them a new card with three lines of differing lengths. One of the lines on the card was clearly the same length as the line on the previous control card. 

Glycolysis and gluconeogenesis are two glycolytic pathways involving the degradation and synthesis of pyruvate from glucose. While these reactions seem like the opposite of each other, gluconeogenesis actually bypasses three pathways involved in glycolysis. The three irreversible reactions must be bypassed due to their change in free energy. The reactions using the enzymes hexokinase, PFK-1, and pyruvate kinase yield a large negative change in free energy making the reaction impossible to reverse. The changes in free energy for the respective pathways are -33 kJ/mol, -22.2 kJ/mol and -33.2 kJ/mol. When a reaction has a change in free energy that is 0 or close to 0, it is easy to reverse and therefore works in the process of gluconeogenesis. However, if the reverse reaction for glycolysis is necessary, the cell uses another pathways and another enzyme to bypass the irreversible change in free energy. Gluconeogenesis is an anabolic pathway because it creates complex molecules from simple molecules. Prior to coupling, the pathway is endergonic and cannot be reversed. 

Cells have control of where DNA replication is initiated as well how many times it is initiated. ORC (origin replication complex) initially binds to the origin of replication on the DNA and causes replication to go off in two directions. Once two replication complexes meet up in the middle, they finish their replication and dissociate. For our purposes we will assume that ORC is bound to DNA all the time. ORC binds, recruits Cdc6 (an ATPase), which then recruits other complexes, including helicase(MCM). Cdt1 brings helicase to the ORC. In S-phase, CDK phosphorylates the ORC, cdc6 and helicase. This effectively prevents the formation of the preRC (pre replication complex). This ensures that the DNA is only replicated once during one round of the cell cycle. PreRC assembly is known as origin licensing. When Rb lets go of E2F, the preRC is assembled. Phosphorylation of ORC stop cdc6 from binding, phosphorylation of cdc6 degrades it, phosphorylation of helicase cause exporitin to bind it and take it out of the nucleus. CDK is responsible for replication initiation as well as ensuring replication only happens once.

Cyclins provide binding interfaces for substrate targets, substrate specificity. Cyclins bind to CDKs and activate them. Cyclin levels rise and fall corresponding to the part of the cell cycle the cell is in! CAK (CDK activating kinase) adds phosphate to T-loop, enabling CDK to phosphorylate and activate its substrates. WEE1 kinase phosphorylates CDK at a different amino acid and holds it in an inactive state. Cdc25 removes that inactivating phosphate added to CDK by WEE1 and activates it (activating phosphatase). CDK phosphorylates Rb and causes its dissociation from E2F. Rb binds E2F, preventing it from causing over replication, when Rb is phosphorylated, it lets go of E2F. When E2F is active, the cell has committed to the cell cycle.  P53 can detect problems during replication and will act as a transcription factor for inhibitors of the cell cycle such as CDKI. It will wait until things are fixed or activate apoptosis if it goes on for too long. CDKs 1,2,4, and six are present in vertebrates. CDK1 is the most important.

The cell cycle consists of four main stages, G1 phase, S-phase, G2-phase, and M-phase. G1 is considered the start of the cell cycle and know as the growth or gap stage. In addition, G0 is the phase in which the cell stays in for the majority of its life, in a nondividing state. During G1, the cell prepares all of the various nutrients and materials needed to replicate its DNA. It can also encompass the synthesis of organelle copies and check for growth signals. At the end of G1, there is a checkpoint that checks for damaged DNA, enough nutrients, and correct growth factor signals. Following G1, the cell enters S-phase. During this phase, the cell copies all of its DNA and DNA replication can be halted to fix damaged DNA. If it cannot be repaired, then the cell undergoes apoptosis.  Next G2 phase begins and further growth proceeds as the cell prepares for chromosome segregation. The G2 checkpoint ensures that the copied DNA is not damaged or incomplete. Finally, the cell enters M-phase. Spindles, which are made up of microtubules and other proteins attach to the chromosomes and pull them apart, eventually resulting in cytokinesis and two copies of the same cell. The M-phase checkpoint ensures that chromosomes are all properly attached to the mitotic spindle. If not, CDKI prevent the function of CDKs and effectively stop the M-phase. Again, if the cell cannot fix the issue it undergoes programmed cell death.