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Few questions about biology

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Few questions about biology

Postby bubblesbamboo » Sun Sep 20, 2009 12:47 am

I'm studying biology right now and I find it fascinating. But I have many questions, so I hope you guys can clear things up for me. :) And maybe you'll find these questions quite annoying and nonsense, (as my mom says) but plz bear with me..
1: How do bacteria move? I mean I know for example some them have flagella, but I don't think rocks can move if they had them? I read something about electromagnetic stuff but don't really get it.

2: Exactly how did bacteria form? where did the organelles come from? How did DNA form? are they just atoms randomly came together?

3: (mitosis) In DNA replication, where did the floating nucleotides come from?

4: Do cells in our body spend all their life preparing for mitosis? Do they just perform their functions as a way to prepare for cell division?

5: Do DNA only form chromosomes before cell division?

6: In mitosis, are the spindles always there? or do they form during mitosis and then disappear?

7: Feel free to add additional information! I would love to learn more.

Answer what you like, but please don't leave out the details. I really want to get this stuff.:)

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Postby JackBean » Sun Sep 20, 2009 9:25 am

try this http://tinyurl.com/cell-cycle-book
(The cell cycle: principles of control by David Morgan on Google Books)

Cis or trans? That's what matters.
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Postby bubblesbamboo » Tue Sep 22, 2009 9:10 pm

Can anyone answer these questions? It's driving me crazy! T_T Are these not the type of stuff to ask?
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Re: Few questions about biology

Postby jonmoulton » Wed Sep 23, 2009 8:25 pm

I think the problem is that no one want to invest the time in answering so many questions carefully. You will be more likely to get a good response if you post just one question. Later, you can post another.
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Postby canalon » Thu Sep 24, 2009 1:24 am

1- at the right scale a flagellum would move a rock. The structure with rotor/stator is quite interesting. So cilia and flagella are actually good way of moving. I am not aware of use of electromagnetism by bacteria for motility, but they have other way to move. Like gliding.

2- The exact origin of life is still unknown, but now one bacteria comes from another bacteria, no spontaneous creation. The same answer applies to DNA. Nobel prize would probably come to whoever could come with a definitive answer, but I suspect that this will never be answered. Plenty of different organelles, some are probably just clever use of membrane, some (plasts and mitochondria) seem to come from ancient bacterial symbionts that completely fused with the ancestors of the eukaryotic cells. There have been at least 2 separate such events (one for mitochondria, the earliest one, and 1 for the plast later it what was going to be plants). Read about endosymbiosis.

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Re: Few questions about biology

Postby Sophyclese » Sun Sep 27, 2009 7:37 pm

I will try to answer as many questions as possible. I hope I can increase your knowledge of Biology through doing so.

1.Bacteria move mostly by attaching itself temporarily to a host's skin and hopping off, for lack of better term, when another surface is reached. Bacteria hop on to a host simply by contact towards the surface the bacteria is residing on and hop off via the same method: contact.

2. I will not say that bacteria actualy "formed". If I were, I would be in cahoots with the theory of evolution. But, according to the theory ot evolution,

3. Free floating nucleotides are achieved when there is a knew nucleotide that has just formed.

4.Whether or not a cell spends all its life preparing for mitosis is dependent upon the type of cell. A skin cell, in a sense, spends its life preparing for mitosis. However, while it waits, it still performs its daily/normal functions. I do not know of a cell that has a daily/normal function that prepares it for mitosis.

5. No, DNA does not produce chromosomes for a cell to perform mitosis. Mitosis is a form of asexual reproduction (self replication). Cells therefore do not need an out-side force to reproduce chromomsomes for it. During mitosis, cells reproduce its own chromosomes to make the new cell.

6. The spindles are there befroe and remain after mitosis in plant cells. In cells of the human body, however, the spindles appear at the beginning of mitosis and dissappear afterward.

7.It would be easier to learn about the cell if you learned the part of cells and the fifferent types.
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Postby mith » Mon Sep 28, 2009 3:26 am

1. bacteria doesn't necessarily have hosts nor do they "hop" since they have no feet.
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Postby jwalin » Mon Oct 12, 2009 12:00 pm

4. a few cells may never divide again.
any cell after it divides can either form a cell that further goes on further replication or specialization.
ever heard of RBC dividing
atleast i have never.
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Re: Few questions about biology

Postby kolean » Tue Oct 13, 2009 7:36 pm

1. Bacteria move thru many locomotive methods. The propelling of a whiplike flagella is one, the other one is cilia which has the same tubulin proteins that form the appendages. The other is actin fibers that produce a filiopodia/lamellipodium. These fibers are composed of beads of actin that can polymerize into a long thread. The actin can move the cell forward by polymerizing the actin on the front end, while depolymerize at the back end to pull the cell's back end forward. Signalling from the environment on the cell's receptors can steer the cell towards as location it wishes to move to, or the oppose if it is a hazard environment: chemotaxis. There can also be receptors for light: phototrophs. Same could be said for electromagnetic fields I suppose. Could be for anything as long as there is a signaling receptor for the cell to respond to.

2. I like the theory that RNA virus was the first to make a DNA. Virus just needs a capsid to contain the genetic material (DNA or RNA) and machinery to replicate itself, and that is all. From there, the RNA duplicated itself. Started to make more and more RNA, so it started to get longer and longer. From there some mutations occurred here and there, and suddenly it was making its first protein that wasn'[t needed for replicating itself. Perhaps a flagella! And then it met another virius that had a different mutation pattern, and they shared the info/genetic material (first conjugation - sexual replication). Organelles would be down the road a long ways till the virius becomes a cellular component, and finds that if it concentrates its ATP production to a certain place near the flagella it made, then a mitochondrion could possibly occur.

3. Cool youtube video: http://www.youtube.com/watch?v=4jtmOZaI ... re=related. The floating nucleotides are very ample in concentration in the environment of the organism. In fact, the energy of the system in the form of ATP is the same one used to supply the A(denine) for the DNA replication.

from Wikipedia on the biochemistry and synthesis of pyrimidines: Both adenine and guanine are derived from the nucleotide inosine monophosphate (IMP), which is synthesised on a pre-existing ribosome through a complex pathway using atoms from the amino acids glycine, glutamine, and aspartic acid, as well as fused with the enzyme tetrahydrofolate.

4. There are many kinds of cells in the human body. Just as there are many cell types that make up a tissue in our body, and then from the tissues we make organs which function as a system for the organism: the human body. I like how you ask if they spend all their "life" preparing for mitosis. Some cells do not have a "life" yet, and I call those stem cells. They have the potential to replicate into any cell (embryonic stem cells) or cell line/type (adult stem cells that are differentiated down a certain path already, but a ready to be whatever cell that path needs: for example the white blood cell line can become many cell types in that line - lymphocytes, basophils, monocytes, eosinophils, neutrophils, macrophages, and dendritic cells). Other cells have a sweet short "life" and perform their functions quickly and then yes, proceed thru mitosis. Some of these cell's 'lives" are functionally exhausting and taxing on their cell and breakdown. Thus the turnover of some cells is rapid (red blood cells, intestinal cells, skin cells). Then there are some cells that are made and they are in a state of quiescence: the Go state of the cell cycle. They do not replicate, and perform their function, and do not replicate again for the life of the organism. Examples of this could be certain neuron cells/brain cells, female oocytes are given a chance to continue meiosis every month, and then upon fertilization gets a chance at mitosis, and another example would be cells from the immune system that are not activated by antigen.

5. DNA is tightly packaged into chromosomes for cell division. It has to be all nicely prepared for the microtubles to connect to the chromosome's kinetochore, and begin the process of dividing the genetic material carefully into the dividing sister cells to be. Now during interphase, when the cell is doing its function, the DNA can be compacted into heterochromatin to keep that part of the DNA repressed and keep it silent. Whle the unbound DNA, euchromatin, is free to be transcribed.

6. Spindles are a general and vague term for me. Microtubules are always present in the cell to give its shape, and even to help it in its locomotion functions. Microtubules are what is polymerized from the centrioles. Centrioles duplicated during the late G1 phase as the nuclear envelope regresses back into the ER. The centrioles are the MTOC (mitotic tubulin organizing center) that takes the protein of polymerization (tubulin) and forms the microtubules for the astral and centrosomal spidles that are made specifically for the binding of the chromosomes' kinetochore. Centrioles do not disapear.
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