Need help with a biology essay (cell replication)

Introduction: Cell replication isn’t very complicated when you just study the basic of it (that’s why we do it in 9th grade in Sweden). However some creationist sites have started to make wild claims about mutations being unable to add new information. Other sites are trying to use arguements along the lines of “if mutations were true would everyone become a mutant and die”. Both claims are false and heres a basic rundown on why it’s false.



Lets take the basics first, we are built of different sorts of cells (liver cells, brain cells etc). Each cell got a core where the DNA is located. The DNA is the blueprint of our body, each cell contains all the DNA we have inherited from our parents, different parts are however active depending on what the cell is used for (liver cells and brain cells contain the same DNA but different parts of the DNA string are active). DNA strings are made up of carbonhydrates and nitrogen bases. There are four different types of nitrogen bases named G (guanine), C (cytosine), A (adenine) and T (thymine). The nitrogen bases fits together on the DNA string as shown on the picture below. Notice that the only pairs are TA and GC (and AT, CG). Any other combination is impossible due to lack of bindings (it’s rather advanced chemistry and this is just the background so I won’t go into it).





http://www.ndsu.nodak.edu/instruct/brewer/images/



The DNA is filled with both active and unactive sequences. The active parts are regularily used to send information to the Ribosomes that create the amino acids that are needed to form proteins. What the unactive sequences do should be pretty obvious (the name gives a good hint).



Cells replinish themselves by cloning. Yes it sounds abit nasty but cloning just means you attempt to create an exact copy of the original. In the case of the cell is the cloning taking form of the DNA vertically separating itself into two halves (instead of a serie of pairs like on the picture would you have two changes of single nitrogen bases G,G,C,T and C,C,G,A). Each DNA half then rebuilds the lost part of the DNA string and moves into their own cellcore (the whole cell duplicates itself but I will focus on what happens in the core since that is the only part that is important when it comes to understanding mutations). It’s in the rebuilding stage that most mutations occur. We are currently not sure on how common mutations are are but most agree that the chance is around 1/10^11 (that means once every hundred billion times a nitrogen basepair is recreated). Theres approximatly 6 billion basepairs in each cell so every 20th time should a mutation occur (ie the DNA sequence is in some way altered at one place). On average is every cell divided 30 times so each cell should contain one or two mutations on average. So why doesn’t the mutations kill us? The reason for this is simply, most mutations got little or no effect. A mutation is most likely to occur in an inactive region that means that the cell either starts to produce a new protein or (which is more likely) nothing happens. If the mutation actually occurs in an active sequence is it possible that the change doesn’t have any effect since different genes (gene=a set of 3 nitrogen bases that determines which amino acid will be created when the information is sent to the ribosome) can create the same amino acid. However different amino acids can also be used to create the same protein. However if the function of the protein is changed will the cell either start working better (here evolution waltzes in if the mutation was in a reproductive cell (what is the English name of those?)) or worse which can cause the cell to die (game over for that cell but the creature will probably survive since cells die and becomes replaced all the time) or if the creature is really unlucky cause cancer (the cell goes on a dividing spree and starts dividing at an extremely high speed).

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Do you wish to edit the biology or the english?

I can certainly do the latter if you wish.

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red blood calls do not have a nucleus. I think they are the only cells without it.

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I would be more than pleased if you edited the english.

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"The problem isn't stupid people, the problem is that lightning bolts aren't distributed properly".

"We are both Atheists.. I just believe in one less god than you do."

"God made me an atheist, who are you to question his wisdom?"

I will get back to you on both soon. I have an immunology test this morn, but wait until the afternoon

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Not being nit picky just a few things to consider..

By cloning you mean Mitosis, right? P,M,A,T followed by cytokinesis.

And also, regarding the cancer they (the cells) also lose their ability to be anchored to the ECM (extra-cellular matrix) Also as in skin cancers the Cadherins proteins) that link the cells together breakdown causing division.

Also you mentioned Brain cells and Liver cells. Yes they both have the same DNA but remeber that Neural tissue does not divide (perform Mitosis) example: If someone gets a brain tumor it is from Neuroglia (support and clean-up cells) division rather than the actual Neuron division. (this type does happen in children up to 4 yrs. however.)

You are doing good,

Not sure how in depth you want to go? Let me know if I can be of assistance or you would like any additional information on the cell.

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None of the gods love wisdom or desire to become wise, for they are wise already -- nor if someone else is wise, do they love wisdom. Neither do the ignorant love wisdom or desire to become wise; for this is the grievous thing about ignorance, that those who are neither good nor beautiful nor sensible think they are good enough, and do not desire that which they do not think they are lacking.

Plato, Symposium 203E-204A

Also, when you explain mutations you could tell them about point mutations, mis-sennse, nonsense and frameshift, or is this deeper than you want to discusss?

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None of the gods love wisdom or desire to become wise, for they are wise already -- nor if someone else is wise, do they love wisdom. Neither do the ignorant love wisdom or desire to become wise; for this is the grievous thing about ignorance, that those who are neither good nor beautiful nor sensible think they are good enough, and do not desire that which they do not think they are lacking.

Plato, Symposium 203E-204A

You got it . Allowing them to maneuver through slim passage ways (veins) and elongate. They also have a relatively short life span.

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None of the gods love wisdom or desire to become wise, for they are wise already -- nor if someone else is wise, do they love wisdom. Neither do the ignorant love wisdom or desire to become wise; for this is the grievous thing about ignorance, that those who are neither good nor beautiful nor sensible think they are good enough, and do not desire that which they do not think they are lacking.

Plato, Symposium 203E-204A

I actually edit papers for a lot of people. Your English isn't bad at all, how long have you been learning? Anyhow, I edited it to make more sense to a native English speaker.



[quote=Taffsadar]









Cell replication is not a very complicated subject at root (which is why we Swedish students study it in 9th grade). However, there are some creationist sites that make wild claims. One such claim is that mutations in cells are unable to add new information. They argue that “if mutations were true, everyone would become a mutant and die.” This essay posits that the claims of "cells are unable to add new information" and its corollary, "everyone would become a mutant and die," are false.




Firstly, we are built of different sorts of cells (liver cells, brain cells etc). Each cell has a core called the nucleus where DNA is located. DNA is the blueprint of our body, and all cells contain DNA inherited from our parents. Different parts of the DNA are active or inactive depending on the cell's purpose (i.e. liver and brain cells contain the same DNA, but different parts of the DNA are active). DNA is a long strand made of carbohydrates and nitrogenous bases. There are four different types of nitrogenous bases: guanine, cytosine, adenine, and thymine (abbreviated G, C, A, and T respectively). The nitrogenous bases fit together on the DNA strand as shown in the picture below. Notice that A pairs with T only, and G pairs with C only. Any other combination is impossible due to the fact that if they were paired differently, the double strand would be too short of too long in places. Only when the pairings are A-T and G-C is the DNA an appropriate size.






http://www.ndsu.nodak.edu/instruct/brewer/images/




DNA is filled with both active and inactive sequences. The active sequences are regularly used to send information to the ribosomes, which create the amino acids that are needed to form proteins. As their namesake implies, inactive sequences do nothing.




Cells have a certain life span, and must replenish their numbers by replication. Replication begins by the double stranded DNA denaturing (separating into two strands). Each half then rebuilds the opposing side then the fully formed DNA moves into its own cellcore (the whole cell duplicates itself but I will focus on what happens in the core since that is the only part pertinent to mutations).

Most mutations occur when the DNA halves rebuild the opposing side. The chance of is around 1/10^11. There are approximately 6 billion basepairs in each cell, meaning a mutation should occur every 20th replication cycle. The most common mutation is a point mutation: only one base pair is changed. On average, every cell divides 30 times, which means each cell should contain one or two mutations on average.

If there are so many mutations in our body, how are we able to keep on living? Do not these mutations kill us, as the creationist websites conclude? No, and the reason for this is simply that most mutations have little or no effect whatsoever. A mutation is most likely to occur in an inactive region since inactive regions comprise most of our genome. This means that nothing happens. If a mutation does occur in an active region, it is possible that the change is ineffectual since different genes can create the same amino acid. For example, a mutation may occur in the sequence ACG, in which the C is removed, but it is just replaced by another C. In other cases, ACG may be altered to CCG. Still, there is no effect since many nucleotide triplets code for the same amino acid. In the case where the mutation does change the nucleotide triplet, the protein produced (or not produced) may either help or hinder our bodily functions.

The claims of the creationist websites are outlandish and embarrassing in light of reality. As evidneced in this paper, mutations occur, which add or subtract new information to the cell. And these mutations, most of the time, have no effect at all, much less a deleterious one.[/QUOTE]

I added a lot to it actually. I hope you don't mind.

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I've edited it a little... enjoy

Introduction: Cellular biology isn’t so complicated when you just study the basics of it (which is why we do it in 9th grade in Sweden). However some creationist sites have started to make wild claims about mutations being unable to add new information. Other sites are trying to use arguments along the lines of “if mutations were true would everyone become a mutant and die”. Both claims are false and here's a basic rundown on why.



Lets take the basics first. We are built of many different types of cells (liver cells, brain cells etc). Each cell has a nucleus where DNA is located. DNA is the blueprint of our body which contains genetic instructions, and most cells contain all the genetic information we have inherited from our parents. Different parts are, however, active depending on the cells function (liver cells and brain cells contain the same DNA but different parts of the chromosomes are active). Chromosomes are made up of a sugar-phosphate backbone and nitrogen bases. There are four different types of nitrogen bases named G (guanine), C (cytosine), A (adenine) and T (thymine). The nitrogen bases have a complementary attraction to each other as shown on the picture below. Notice that the only pairings are TA and GC (and AT, CG). Any other combination is resisted due to a repulsion force, and mismatches are often excised (it’s rather advanced chemistry which i wont go into).





http://www.ndsu.nodak.edu/instruct/brewer/images/



DNA contains both active and inactive sequences. The active areas are regularly used by ribosomes to create protein strings using amino acids. The inactive strings are not translated.



Many cells can duplicate themselves by mitosis. While it may sound a bit strange at first, mitosis is just a process to produce a highly similar copy of the original. Within the cell, DNA is copied using many different enzymes which separate the chromosomes into two halves, lengthwise between the bases (instead of a series of pairs like on the picture you would have two changes of single nitrogen bases G,G,C,T and C,C,G,A).
Each half chromosome then becomes the template for a complementary DNA string, which is produced and thereby doubles the chromosome number within that cell. The chromosomes line up symmetrically along a cellular midline and then the cell pulls itself into two daughter cells, each with an equal chromosome number (the whole cell duplicates itself but I will focus on what happens in the core since that is the only part that is important when it comes to understanding mutations).
Most mutations occur within the process of doubling the chromosome number. Biologists are not currently sure how common mutations actually are, but most agree that the chance is around 1/10^11 (that means once every hundred billion times a nitrogen basepair is recreated). There are approximately six billion basepairs in a nucleated human cell. Mutations appear at a modest rate, but many are corrected by proofreading mechanisms. So why don't the uncorrected mutations kill us? The reason for this is simply because most mutations have little or no overall influence on the cells metabolism. A mutation is most likely to occur within an inactive region, and that means that the cell won't even transcribe the error. If the mutation actually occurs in an active sequence it is possible that the change won't have any effect on the resultant protein since different codons (codon = a set of 3 nitrogen bases that determines which amino acid will be used when the information is translated by the ribosome) can create the same amino acid and many proteins can still function with minor structural changes. However if the function of the protein is dramatically affected (like having a mutation in a complementarity determining region), the cell may either start working better (here evolution makes an appearance if the mutation was in a germline cell) or worse which can result in cell death (game over for that cell but the organism will probably survive since cells die and becomes replaced all the time). In unlucky cases, the mutation can result in cancer, where the cells normal regulatory processes are over-ridden (this results in malignant growth into a tumour).

Mutations are inevitable errors produced during the cell replication process. There is no divine force behind it, as it is just a result of statistical probability. Mutations sometimes have detrimental effects to the organism, even less have beneficial effects, but most have no significant effect at all.

The study of cell biology and mutations has direct application to medical science. Christian science has none.

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