Discussion

Submitted by dalon on Sun, 11/12/2017 - 21:01

Trimyristin and myristic acid were obtained through an extraction reaction using recrystallization and hydrolysis techniques with tert-butyl methyl ether and acetone. The products were primarily identified using melting points and their identity and purity was assessed. The observed melting point of once recrystallized trimyristin indicated an impure substance due to a wide 5 degree range of melting and a lowered melting point in comparison to the accepted melting point of trimyristin of 56–57 °C. In recrystallization, in order to obtain a pure compound, insoluble impurities are removed by dissolving the compound in a solute that has similar structural features then filtering out any insoluble impurities; thus, to further purify the impure trimyrisitin, as determined by the melting point, we had to recrystallize again to remove the impurities remaining in the compound. The twice recrystallized trimyrisitin resulted in a purer product as indicated by the small melting point range, 54-56°C; however, it should be noted that the observed melting point is still slightly lowered than the accepted melting point and could potentially indicate a still impure product. Myristic Acid was obtained from the once recrystallized trimyristin with a melting point of 49-52°C, with the accepted melting point of 54.4°C. The wide range and lowered melting point again indicate an impure compound. In order to improve the purity and yields, as indicated in the results section, of the products, we should allow the crystallized solution to cool completely to room temperature before submerging in the ice water bath. Not only will this result in larger crystal formation, but it would ensure that all the ether soluble components would dissolve before being put into the ice bath and thus the purity of the crystals would improve because the soluble dissolved impurities would be fully filtered out upon filtration. The purity and identity of the products were tested and the twice recrystallized trimyristin was determined to be pure; however, the once recrystallized trimyristin and myristic acid were determined to be impure.

MV plate yeast mutants

Submitted by daniellam on Sun, 11/12/2017 - 15:54

The MV plate for Identifying mutant strains showed how complementation can allow for the identification of unknown mutant strains. For MA1, the parental strain turned pink in the MV media, this indicated that it may be an Ade1 mutant since it takes time for metabolize CAIR; but this gave time for white coloration to form before the red coloration set in (turning the color pink). The MA1/HB2 mating turned white showing complementation; since HB2 is an Ade2 mutant, MA1 must be an Ade1 mutant to complement. The MA2 parental strain turned pink, this may mean that MA2 also has a mutation in the Ade1 gene. All of the MA2 matings were either red or pink, indicating that MA2 may be a mutant for both Ade1 and Ade2; there is no complementation that occurred. Another possibility is that the MA2 strain is a mixture of multiple strains of yeast since other groups in the laboratory received positive results for complementation with MA2. The MB2 parental turned red meaning that it may have a mutation in Ade2. The MB2/HA1 mating further supports MB2 being an Ade2 mutant because it turned white, meaning that there was complementation between HA1(Ade1 mutant) and MB2 which must be an Ade2 mutant. A similar pattern can be seen with MB4: the parental is red and the MB4/HA1 mating turned white. This means that MB4 is also an Ade2 mutant (Table 2). 

start of methods

Submitted by cberg on Sun, 11/12/2017 - 15:23

There will be a total of 72 planarians that will be divided equally into eight groups. Each group labeled 1-8 will experiment with the control environment and one of the eight experimental environments.

On Wednesday, November 15th, upon receiving 9 planarians, each group will distinguish 3 planarians for the control environment, 3 planarians for condition 1 of their experimental environment, and the last 3 planarians for condition 2 of their experimental environment.

Group 2, referenced in Table 1, will be experimenting with planarians in different intensities of light. This group will plate 3 petri dishes with Great Value Walmart water and label the dishes as “control,” “experimental condition 1,” and “experimental condition 2,” with the respective planarians placed into each petri dish. Starting with the control dish, one planarian will be measured at its fully extended length and this length will be recorded. After measurement, the group will cut this planarian exactly in half. The tail half of the planarian will then be placed into a condiment cup labeled “control planarian #1,” which will be filled halfway with Great Value Walmart water. The group will repeat this process for the remaining two planarians for the control group, labeled planarians #2 and #3. These three cups will be placed in an area of Room 301 that receives normal indoor light exposure. Next, the first planarian in the experimental condition 1 petri dish will be measured at fully extended length and will then be cut in half. This planarian will be placed in a condiment cup labeled “Lamp Light Environment Planarian #1,” which will be halfway filled with Great Value Walmart water. This group will repeat this process for the remaining two planarians in the lamp light experimental condition, labeled planarians #2 and #3. These three cups will then be placed directly under lamp light in room 301. Finally, the first planarian in the experimental condition 2 petri dish will be measured at fully extended length and then cut in half. This planarian will be placed in a condiment cup labeled “Dark Environment Planarian #1,” which will be halfway filled with Great Value Walmart water. This will be repeated for the remaining two planarians in the dark experimental condition, labeled planarians #2 and #3. These three cups will then be placed underneath a cardboard box in room 301.

 

Ether Synthesis

Submitted by msgordon on Sun, 11/12/2017 - 12:58

In this lab, butyl naphthyl ether was synthesized from 2-naphthol in the presence of sodium hydroxide, ethanol, and a butyl iodide using a Williamson Ether Synthesis reaction. The melting point of the resulting product was determined to be a range of 30℃-32℃, which is slightly below the literature value range (33℃-35℃). The relative proximity between the experimental melting point and the literature melting point range suggests that the product is fairly pure. Since there is a 1:1 ratio between the moles of 2-naphthol and butyl naphthyl ether, the theoretical yield of the reaction is 0.278 g, however the mass of the product was found to be 0.05 g, giving a percent yield of 18%. The low yield can be attributed to the loss of product through filtration. In future experiments, this mass loss could be avoided by using a different compound to cool the product without causing an overflow of liquid in the funnel during filtration that occurred when ice was used. Thin layer chromatography was used to further assess the purity and polarity of the product. The first solvent used consisted of a 95:5 mixture of hexanes:ethyl acetate. However this resulted in an uneven separation, presumably because of the high amount of the nonpolar hexanes compared to the polar ethyl acetate. On the other hand, a TLC test using a 95:5 mixture of ethyl acetate:hexanes resulted in an excessive amount of separation due to the high polarity of the solvent. Thus, it was a mixture of 90:10 hexanes:ethyl acetate mixture that provided the best separation. The presence of only one spot in the product column of the TLC plate indicated that the product is pure and consisted of only one component. However, this does not entirely confirm the purity of the product, as a single spot could be comprised of both the desired product and a second component of similar polarity. The product spot experienced a considerable amount of separation(Rf = 0.85) which was expected as butyl naphthyl ether is a relatively nonpolar compound and should show separation. 2-naphthol is a polar compound however, and thus should not experience much separation which was evident in the starting material spot and the co-spot (Rf = 0.17). As such, the results of the TLC analysis suggested that the product was indeed butyl naphthyl ether.

Bio 542 review

Submitted by msgordon on Sun, 11/12/2017 - 12:54

The Chondrostei group is comprised of Polyodontidae and Acipenseridae. Psephurus is a member of the Polyodon family that is presumed to be extinct - the last known specimen was caught in 2007 and was found in the middle - lower part of the Yangtze and associated bodies of water. Brought to extinction b/c of the three gorges dam and illegal fishing. Polyodon occurs in the Mississippi River, Missouri River, Ohio River and associated systems. It is a ram feeder and filters zooplankton out of water column w/ gill rakers. The paddles found in Polyodontidae specimens serve as electrosensory organs used to detect changes in electric fields. Similar to ampullae of Lorenzini, used to detect plankton.

Area 4 and 6

Submitted by kmydosh on Sat, 11/11/2017 - 22:00

Area 6 of the motor cortex is primarily involved in the planning of executing a physical action. Area 4 is involved in the actual execution of the action. An experiment with a money demonstrates this. The monkey must touch a certain button only after the button lights up. A light above the correct button lights up but the monkey can only get the reward when the button itself lights up. The light above the button is the instruction stimulus. The button itself lighting up is the trigger stimulus. Before any lights are on the neurons in Area 6 are not firing. When the instruction stimulus comes on the Area 6 neurons start to fire. When the trigger stimulus is on the neuron fires and then gradually stops. Meanwhile, when the Area 6 neurons stop firing as radidly, the Area 4 neurons start firing as the monkey executes the task of touching the button. This experiment demonstrates what areas of the motor cortex are involved in moving. 

Exam 2 review

Submitted by msgordon on Sat, 11/11/2017 - 17:16

The four genera of Acipenseridae include Acipenser (17 sp, NA, EU, Asia), Huso (2 sp EU, Asia), Scaphirhynchus (3 sp NA),  and Pseudoscaphirhynchus (3 sp central Asia). Acipenseridae first evolved in the late Cretaceous. External characteristics include 5 rows of later trunk scutes, 4 sensory barbells (chemoreceptors), a heterocercal tail, subterminal mouth. These fish are anadromous. The Aral sea is/was a body of water in central asia (near Kazakhstan and Uzbekistan aka Ponto-Caspian region) which dried up because of dams and diversions due to irrigation. Acipenser species in MA include oxyrinchus and brevirostrum. Brevirostrum is anadromous and takes 2-3 years to mature in the south and ~11 years to mature in the north. Originally migrated up the Connecticut river to spawn but dams impeded this. Following the construction of dams, they were separated into populations above and below the Holyoke pools, and now have to be manually moved up above the dam in order to breed

Neurobio Paper 2 Draft Part 2

Submitted by samihaalam on Fri, 11/10/2017 - 23:11

Figure 1:

A:

  • fluorescently labelled, melanopsin genes = red
  • confocal microscopy
  • shows different optical sections

B1:

  • shows one layer, then B2 showss a different layer
  • shows they seem to overlap - some kind of network

C:

  • different layers of the retina
  • · = soma, - = dendrites
  • showing how one cell ineracts with others!

D:

  • shows their total results

E:

  • every dot is melanopsin cell 
    • it's all over, but seems to be more concentrated in some parts of the cell than others

Figure 2:

  • cross-section of retina, different layers of retina 
  • shows most RGC's in RGC layer
  • dark space: all other melanopsin negative cells around
  • most RGC cells not labelled

A3 and A4:

  • contrasts of INL, showing RGC layer

B:

  • also in other layer, not RGC layer
  • so, cell displaced!

C: 

  • what if melanopsin is recessive? 
  • red = pre-synaptic
  • maybe, green will always be near red
  • BUT, not what they saw, not organized 
  • therefore, melanopsin probably in dendrites!

D:

  • control!
  • antibody labels melanopsin
  • but, need to check that antibody is specific!
  • standard control -
  • mix antibody with melanopsin; 
    • if recognizes melanopsin, will outcompete!
    • if recognizes other target, might see staining
    • but, they saw no staining!  → so by adding melanopsin, will get rid of  other target
  • good antibody!

Figure 3:

A:

  • bunch of stuff in there, here's beginning and end 
  • portions at beginning  and end identical!
    • homologous recombination
    • knock out melanopsin, put in tau lacZ
  • Southern blot:
    • WT vs. heterozygotic mice to compare 
    • cut restriction membranes,
    • checking to see if engineered mice correctly!

B:

  • colocalized together
  • where tau-lacZ expressed should be exactly where melanopsin is expressed 
  • red + green = yellow
    • heterozygote - so 2 copies!

C&D:

  • retina, fine axons going to optic disc

E:

  • optic chiasm! - stained; some melanopsin positive is projecting there

F:

  • optic chiasm at higher magnification

G:

  • SCN, coronal side of hypothalamus
  • both sides of brain lit up!
  • projects to SCN

H&I:

  • mid brain regions -  control pupil size, some melanopsin positive RGC's project here too! 
  • not focus, but also shown here too!

Figure 4:

  • studying photosensitivity, shine light on them!

A;

  • if light sensitivity, should get action potentials 
    • saw change in membrane potential! does something!
    • next step: look at response?
  • shows this cell projects back to SCN and light senstivity and anti-melanopsin

B:

  • other responses to light stimulus
    • membrane voltage changes in response to light

C:

  • control 
    • check that it's not stimulated by other photosensitive cells
    • use cobalt and glutamate to block synapses 
    • usually, rods and cones project to RGC's via bipolar cells and synapses, so need to check the synapses were blocked!
  • this shows RGC's are intrinsically photosensitive!
  • no matter what you add, still get a response!

Physics notes

Submitted by kmydosh on Fri, 11/10/2017 - 19:39

Accommodation

Ciliary muscles around lens change its shape and focal length

Eye’s lens changes shape (changes f ) to focus on objects near and far, Object at any do should produce image at retina (di ≈ 2.0 cm) Lens can only change shape so much • “Far Point” Furthest do where image can be at retina Normally, dfar = ∞ (if nearsighted then closer) • “Near Point” Closest do where image can be at retina Normally, dnear ≈ 25 cm (if farsighted then further)

Myopia: Nearsightedness. If nearsighted, far point dfar < ∞. Object at do > dfar creates image in front of retina. Corrective lens creates image of distant object at the far point of the nearsighted eye. flens such that distant object at ∞ (“normal” far point) is in focus. Flens=-dfar. Negative for diverging lens.

Hyperopia: Farsightedness: If farsighted, near point dnear > 25 cm. Object at do < dnear creates image behind retina. Corrective lens creates image of close object at the near point of the farsighted eye. Flens such that object at 25 cm (“normal” near point) is in focus. Dnear>25cm so flens >0 for converging lens.

Refractive power: Use P=1/f. Units are in diopters. 

Perfect Paragraph: Background

Submitted by brdougherty on Fri, 11/10/2017 - 12:04

The three forms of sweetener observed are pure sucrose, pure brown sugar, and pure saccharin. The chemical formula for sucrose is C12H22O11 and in a similar experiment it was found that sucrose produces a rewarding effect in planarians (Sciencedirect). Them chemical formula for brown sugar is the same as sucrose however it has molasses present in it. While we hypothesis that similar results will be seen in sucrose and brown sugar it has yet to be seen if planarians have a preference between the two. Saccharin which is commonly referred to as sweet n’ low has a chemical formula of C7H5NO3S. Saccharin offers effectively no food energy but is however approximately 300-400 times sweeter than sucrose. While no experiment was done to show if planarians prefer saccharin the group i interested to see if the planarians have a preference for the artificial sweetener.

 

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