dttom

could you explain a bit further with your asymmetric amino acids with examples using currently existing amino acids? By the way, even if you success in changing a living organism to its so-called mirror form, as a matter of fact, pathogens such as virus and bacteria have an extremely high reproductive rate and very short reproductive cycle, I doubt if such 'mirror form' could survive without disease or any other infection or disturbance for thousands years. I don't support this due to that I don't that it would be valuable for us to invest with the profit of just a short period of peace after all. Besides, I doubt if there would be any side-effects, which would cause extra harm to the body and make the matter worse.

I have heard the term 'meme' from the book The Selfish Gene' written by Richard Dawkins, who introduced this term in chapter 11. It is claimed that the so-called meme could be a new replicator other than genes, in which is replicated from brain to brain; besides, it is said that memes which lowers survival rate of the possessor of that meme could evolve as there is nothing to do with the survival rate of the host but all which matter is the meme itself, just like genes in the selfish gene theory. However, if memes 'have to' replicate from brain to brain, this type of dispersal of memes involve 'machines' which involve organic living things, which is the product or phenotype of genes, that is, the transmission of memes have to rely on genes' products. Imagine that if there is no gene, all memes such as songs could not have dispersed or replicated, no matter how large amount of CDs containing those songs exists. This leads me to think about effects or phenotypes of memes which causing harm or bring negative effect to their hosts, in these case, as they would decrease the survival rate of their hosts, any host, as a product of gene conbination, which could selectively resist these memes from shaping their brain (not accepting these memes in mind) could have a higher survival rate than other which could not on average, hence, if it is the case, genes for building a 'machine' which is capable of resisting harmful meme which would decrease the survival rate of one if such meme enter the individual and act on the body reshaping the brain would be prevailing in the gene pool, harmful memes would then start to disappear in the meme pool. If this is the case, such meme-resisting type of individual would have evolved by natural selection, however, I don't know whether this has not occurred or would not occur, I couldn't spot an individual who resists certain harmful meme would have an advantage over rival individual. Either, I could still observe loads of harmful memes existing in the meme pool such as celibacy, which would reduce the survival rate by reducing the chance of propagating genes to offspring, individual possessing gene resisting meme fro celibacy would then have a higher chance to propagate due to the fact the its rivals affected by celibacy meme would be less eager to reproduce, hence, afterward, genes for resisting celibacy meme would prevail in the gene pool, and one of the consequences would be the disappearance of the meme for celibacy. I would like to know whether there is problem in my speculation or is there any other reason which opposes my through. Could anyone help in this issue?

for the point that why did this behavior evolved, the point should be that as there should be variation of some tend to find for mate while others are a bit reluctant to do so. so in this condition, those who fight for mates would have a higher chance to pass thier genes, which contain those aid in the behavior for fighting for mates, on to the next generations. hence, from time to time, such behavior became more common in the population, that is, the behavior was evolved. that is, this behavior, as having an evolutionary advantage to the genes' possessor, hence it was evolved. another point is that, the ability of fighting has somehow be evolved to be an indicator of the quality of the genes within, though some could take advantage from this indication, just like secondary sexual characters, so the winner of the fight would be attracted by more opposite sex mate, and hence thier chance of passing genes would be greater.

Mitochondria need nuclear gene to maintain, so I think it would only be possible that at least such substances (finally translated proteins from nuclear genes) could be provided, while there is too low possibility to make to be practical. also, there may involve some communication between cells or with outside environment to maintain the mitochondria, so I think besides this is rather not practical, it would also be not possible.

the original version I read is in chinese: http://hk.news.yahoo.com/070327/12/24i6e.html while I later find an English version: http://science.slashdot.org/article.pl?sid=07/03/27/2059230&from=rss

would there be anything to do with the catalase and sulfuric acid or the sodium hydroxide? and I suggest to count the time needed to produce a certain amount of gas instead of fixing a time and count the volume of gas produced. besides, how do you know catalase work best at pH10, from textbook or internet? has it claimed that it is in vitro or in vivo, such could matter.

so to perform your osmosis experiment, what you need is just a selectively permeable member, so if the grape skin is scretched, I think it would not matter. on the other hand, I doubt if the grape skin is not permeable to water, if it is not, so certainly water could not get across the grape skin and your experiment failed, as I am not sure whether it is permeable to water, I can't decide it now.

the line connecting the oxygen atom and hydrogen atoms you showed in yoru diagram means covalent bonds between atoms, so you could just draw such diagram with covalent compounds; with ionic compounds, you could simply draw two ions, for instance, for NaCl, you may just write Na+Cl-; while for a bit complicated ionic compound such as NH4MnO4, if you like, you may draw, H | [H-N-H]+ | H for ammonium ion; and O- | [O=Mn=O] | O for manganate(VII) ion; if what you would like to represent is simple element, you may just write its element symbol.

It was recently revealed that there is case that one egg being fertilized by two sperm simutaneously, with the resulting zygote alive! So in this case, the resulting zygote would be triploid, differing from the normal diploid zygote, in which case that normally the triploid zygote would be dead. It is claimed that after the egg is fertilized by two sperms, it divides to two balls of cell, forming two zygotes, let the two sperms as a and b, one of the zygotes possesses the gene set from its mother and that of a; while another zygote possesses, again the gene set from its mother, and that from b. So now I wonder how this could be done, the zygote formed is triploid, and the chromosomes from each sperm should have been mixed, while two zygotes with exact chromosomes from either sperm and the egg are formed, how could exact chromosomes from one sperm be extracted from the mixed chromosome forming zygotes possessing exactly chromosome from one sperm and the egg?

DNA polymerase probably aids in the process of DNA replication, so if gene for this protein (DNA polymerase) suffers from a deleterious mutation, probably few amino acids which should have appeared in the sequence would be missed, and if such amino acids are vital to the function (activity) of the enzyme, the cell would probably get error during DNA replication and thus also affect the cell division process. while, if the mutation is substitution, the effect would be less negative, in some case, I think. as if the substitution does not affect the sequence of amino acid in the result protein (one amino acid is usually coded by more than one codon), I think there is no much harmful effect; however, if such substitution change the amino acid sequence and unfortunately alter or destroy the function of the enzyme, the effect would be as same as mentioned above when a deleterious muatation occur to the gene.

as for your titration of mixture of coca cola and sodium hydroxide against hydrochloric acid, do you assume the coca cola contains only carbonic acid regarding the reaction involved? as there might be trace amount of other substances such as citric acid and phosphoric acid which may disturb.

let the first term as a; the factor as r a+...+ar^29=91 a(1-r^30)/(1-r)=91 a=91(1-r)/(1-r^30) ---(1) a+...+ar^19=91 a(1-r^20)/(1-r)=91 a(1-r^20)=91(1-r) 91(1-r)(1-r^20)/(1-r^30)=91(1-r) 1-r^20=1-r^30 r^20=r^30 r=-1 a=91(2)/2=91 a+...+ar^9=a(1-r^10)/(1-r) =91(0)/2=0

under a given temperature, I doubt if the salt added to water would have any effect on the self-dissociation of water. as we know that at a given temperature, the dissociation constant of water would be a constant. for instance, the dissociation constant of water at 298K is 1*10^14. so I think the added salt would not have an effect on this matter. for a substance which consumes hydroxonium or hydroxide ions in the water, I think there should be a equilibrium shift rather than a fostering effect of self-dissociation of water. for example, if ammonium ions are added, there should be an equilibrium of: NH4+ + OH- (from water) <--> NH3 + H2O which in turns consuming parts of the hydroxide in water, hence the solution would probably be slightly acidic due to the excess of hydroxonium ions in water.

for question two, though I am not sure I could get the explanation correct, I would like to have a try. for an exothermic reaction, says, glucose --heat--> carbon dioxide + water this reaction could not take place at room temperature, while not enough heat given to it seems not be a limiting agent. the above reaction could not take place just because the reaction does not get enough activation energy, so I think activation energy should not be regarded as a sort of limiting reactant/agent. while for an endothermic reaction, the enthalpy of the product should be greater than that of reactant; so energy absorbed during the reaction is used to enhence the enthalpy of chemical, hence this energy (heat) could be considered as a reactant, hence if the energy given is not enough, the percentage of completion of the reaction, assuming the reaction is irreversible, would not attend one hundred percent. in this way looking into the matter, in an endothermic reaction, heat could be a limiting agent.

1) well, heat means the transfer of thermal energy, so I don't think the product could contain heat, nor the reactant; if you talk about enthalpy contained in product, compared with that in reactant, in an exothermic reaction, which net energy is given out by the reaction, I think the answer should be sometimes true. for an exothermic reaction that A--> B as energy is given out in this reaction, enthalpy of B is probably lower than that in A, hence in this case, enthalpy of product is lower than the reactant's. while for an exothermic reaction that C + D--> E let C has an enthalpy of x J mol^-1; D y J mol^-1; 1 mole of C and D is used in the reaction; even it is an exothermic reaction, I think E could somehow possess x+y-z J mol^-1 of enthalpy, where z is positve real number, and z J of energy is given out in the reaction. so in this case, the product contains an enthalpy higher than either reactant. Hence I think the conclusion would be 'sometimes true'.

you mean solid and hot sulfuric acid? do you mean the environment is under high pressure as the melting point of sulfuric acid is about 10'C while if you want it hot solid...

As I have just finished my final examination in this school year, this is also another question I got the answer incorrect, according to the model answer. The question is about the substitution reaction of methane and bromine in 1,1,1-trichloroethane solution. It is a simple one, how many organic products could be obtained from this reaction in maximum? As I know, it is a reversible reaction, that is, for instance, methane could react with bromine to form chloromethane and hydrogen bromine, and vice versa. Hence I think if I consider methane also as a product would not be incorrect, and as a consequence, I got the answer five, namely, chloromethane, dichloromethane, trichloromethane, tetrachloromethane, and also methane. After that, I ask my teacher about this, while he insisted that methane is not a product but an unreacted chemical/reactant. However, as explained above, methane found at the end of the reaction actually has participated in reaction, and it is formed as a product of the reversible reaction. So any misconception here? I am not quite satisfied with my teacher's answer after all. Could anybody help? Thanks.

This's one of my exam question, the model answer said that noble gases could be obtained from the fractional distillation of liquid air, while I doubt if this statement is correct, though may be due to my misconception. During the fractional distillation of liquid air, after purification of incoming air, the air mainly contain noble gases, nitrogen and oxygen, while the purified air is continuously compressed and expanded, made to a temperature of about 200 'C, which noble gases are not liquefied yet; later the liquid air (containing N2 and O2 only now) is heated and nitrogen and oxygen are obtained at different position of the fractionating column. What I have in my mind is that the procedures after obtaining the liquid air (composed of N2 and O2) are known as fractional distillation of liquid air, but not including the extraction of noble gases, which are not obtained from the 'liquid air'. Could anyone correct me if I have got any mistake, or any opinion would be appreciated.

I've recently written a report on this topic, while there is some problems in the passage, spoke by my professor. would anyone like to have a look at the passage? If so, would you mind leave your email address and I will send it to you... (I do not agree with my professor...)

I am having my exam very soon and I have a question want to ask... it is that, friction between two bodies is determined by the equation, f=Nu, where f denotes the friction force; N for the normal force and; u for the friction coefficient, however, it is also known that the resulted kinetic friction force is proportional to the velocity of the sliding object. So does it mean that the velocity of the sliding object would affect the normal force? Or affect the friction coefficient? And I wonder the explanation for this phenomenon.

well, on my view, AgOH should be too unstable to exist, as Ag+ is small and have a relatively high electronegativity, the hydroxide ion if bounded to it would be distorted so that the 'hydroxide' is no longer hydroxide, instead of an oxide is formed, Ag2O. I think the equation should be: 2Ag+ + 2OH- --> Ag2O + H2O

First of all, cell contents in different differentiated cells are different, so as you mentioned, cell membrane allows substances go in and out, so as to patially control the content inside cell. As cells are differentiated, they perform different functions, and need different materials, so if cell membrane is not present in all the cells, all the material will be mixed, and we can thus not distinguish which cells is which, they just become one cell! Besides, cell membrane separates different parts of the body, for example, cells constructing the blood vessel have cell membrane to separate them from the blood and other organs, otherwise, all the organs would just become a mess, we even can not point out which organ is which!

It is believed that mutation occurs at a steady and slow rate (I know this from book), however, I doubt the point. As everyone knows, innumberous disaster occurs in the history of life, during disasters, for example, an explosion of cosmic ray, may increase the number of mutations in a great degree, so at these times, the so called 'steady and slow' mutation rate is disturbed. So, todays, people uses protein as an indicator to find out the time for two species being apart form the life tree. For instance, if an amino acid difference between corresponding protein in two species represents 50 thousand years (i.e. one amino acid changes from one to another for each 50 thousand years), so people would believe that two species with 3 amino acid difference in their corresponding protein represents that they went apart from the life tree 1.5 million years ago. While, if apply the point that mutation does not occur at a steady rate mentioned above, such calculation might be incorrect, as, if the two species just departed from the life tree 25 thousand years ago, while a disaster occur changing three amino acid constituents in their corresponding protein, we might believe the two species under concern departed from each other 1.5 million years ago, which is not the fact in the assumption. I don't know whether the point I mentioned is correct or not, so I would like to have some suggestions, or someone may point out what's wrong in the view I stand.

Well, I mean other elements, I just take hydrogen as an example which when is included in a gas discharge tube, emission line spectrum could be obtained... http://hk.wrs.yahoo.com/_ylt=AmM09DNODeOltJez6sfdB0m.ygt./SIG=125m26odq/**http%3a//www.thebestlinks.com/images/4/43/Emission_spectrum-Fe.png emission line spectrum of Fe it could be seen that few blue-violet lines are bolden...

While I studying atomic orbitals, I was told that when performing an experiment about the gas discharge tube, which certain gas is contained inside, says, hydrogen, when the gas is under high potential difference, the gas glows and energy is absorbed to promote e- to a higher energy level, when the e- drop back to its ground state, energy is emitted as radiation, so an emission line spectrum is obtained, so now I would like to know, as I has observed, why some of the lines are boldened while some are not. Besides, lines in a series converge into continuum, the line in a series with the longest wavelength represents the wavelength shown by the radiation emitted when an e- drop from a level to the previous one level, so it could be deduced that, take hydrogen as an example, energy emitted by e- dropping from 2s to 1s is always greater than that by e- dropping from infinite energy level to 1s, I would like to know the reason. And the following is another question, when phosporous reacts with chlorine, two compounds are possible to form, namely, PCl3 and PCl5, in case of PCl5, one of the e- in the 3s subshell is promoted to 3d subshell. So now, as I know, 4s is of lower energy than 3d, and e- tends to being of the lowest energy state, if one of the e- is promoted to 4s, five bonds could also be formed, so I would like to know why e- is promoted to 3d but not 4s.