The study of cells: their physiological properties, structure, environmental interaction, division, life cycle, and death, as well as the organelles they contain. Also known as cytology.

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Do chromosomes uncoil in interphase II

During interphase II, there is no S phase in which DNA replicates. However, in this stage, do the chromosomes remain wound? Or have they unwound into chromatin form, and recondense during prophase II? ...
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47 views

Are nucleotides at the ends of DNA stripped on aging?

I had the following understanding (now after reading a popular science article seeming wrong understanding): DNA in (regular) cells (in human and some other organisms) are protected by telomers. ...
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1answer
33 views

cell specialisation and their location

When we create new cells, how come they are of the 'right' type at the 'right' place? For example, when I make a new cell on my lips, it's obviously not the same as a new one in my kidneys. Is the ...
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1answer
53 views

Common genes and enzymes involved in pathogen entry into host

Many microbes like Salmonella, E.coli, Legionella pneumophila etc. enter host cells via cystoskeleton remodeling of the host cell. Do all microbes follow the same path or there are any other ways for ...
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2answers
2k views

Book Recommendations: GRE Subject Test In Biochemistry, Cell And Molecular Biology

There are probably a lot of really good answers that may vary significantly in terms of content. I'm looking for a set of books that I can read in preparation for the GRE Subject Test In ...
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0answers
234 views

Contact Inhibition of Cell Division: Signaling Pathway

The following article refers to contact inhibition of cell division in epithelial cells, specifically MDCK cells: Collective and single cell behavior in epithelial contact inhibition. In their review ...
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14 views

Ions in different cell compartments

I would like to understand the distribution of metal ion concentrations (such as Mg2+) in the different cell compartments. I tried very hard but still couldn't find such information. Could anyone ...
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2answers
62 views

Anaphase Microtubule Disassembly

Centromeres move toward the poles as the microtubules that connect them shorten. This shortening is due to the removal of tubulin subunits from the kinetochore ends of the microtubules. I'm confused ...
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1answer
49 views

Which steps occur in each phase of Meiosis and Mitosis [closed]

MITOSIS In mitosis am I correct in saying that the spindles attach to the centromeres at the end of prophase/prometaphase? (I read this in an answer to another question) MEIOSIS Does the ...
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1answer
40 views

Why only mitochondria and plastids?

Why are there only two unique semi-independent organelles? Why are there no others, symbiogenesis seems like it should be a relatively common thing. So do most organelles just lose all their DNA? Or ...
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2answers
5k views

Why is saltatory conduction faster than continuous conduction?

How does spacing apart sodium and potassium channels allow the action potential to travel faster down the axon? This is the reason always cited for saltatory conduction and myelination, but my mental ...
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1answer
33 views

How chameleons change color? [closed]

Well, I was watching a video about chameleons and I saw that their cells can change color. Can someone explain me how is this possible?
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1answer
84 views

How much of the jejunum is bypassed during gastric bypass?

There is both long and short limb gastric bypass surgeries (along with several other variations on intestinal bypass procedures). How much of the jejunum is bypassed with a long-limb and short-limb ...
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149 views

Why is succinate dehydrogenase attached to the inner mitochondrial membrane?

Succinate dehydrogenase is attached to the inner mitochondrial membrane. All the other enzymes of the Krebs cycle are located within the matrix of mitochondria, though. In biological systems, there ...
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1answer
57 views

What determines whether the maternal or paternal allele is expressed?

I am taking cell biology and have this question: During the process of gene expression, it is possible to express either the maternal allele or the paternal allele. When and how is the determination ...
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1answer
32 views

Where exactly is 'Colloid' with regards to synthesis of thyroid hormones?

I've researched colloid and it seems to be a substance of microfibres and thin films in which thyroid hormones may be synthesised, but I was wondering where this exactly is... I think it could be in ...
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1answer
54 views

What are allogametes? please explain [closed]

Allo means different or unrelated I guess.Please clear me the meaning with some examples.
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19 views

Degenerate primer designing software

Can any one provide online free degenerate primer designing software. I have tried couple of them like CODEHOP is one where BLOCK formatting step finding difficulty, can anyone help me out....
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1answer
60 views

Are surface area or volume conserved during cell division?

I am a student of physics of mathematics with very little knowledge of biology. Nevertheless, I am very keen on biophysics and I'm trying to learn the biological concepts that I need on the way. I'm ...
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1answer
126 views

Cancer in myogenic heart cells? [duplicate]

Why cancer does not occur in myogenic heart cells? Is there any special ability in heart cells to resist cancer ?
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2answers
2k views

Can brain cells move?

I was discussing this with my brother. I'm pretty sure I read somewhere that they can move. Thanks EDIT: By movement I mean long distance migration (preferably within the brain only).
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1answer
64 views

Reseach on feeling pain of other people

I'm more of a tech than bio kind of guy, but I have read and learned a lot alongside of my girlfriend's education. Which is very interesting!! Currently I want to investigate : people claiming to ...
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1answer
447 views

What kinds of cells does human saliva contain?

I have heard that our saliva contains cells. What cell types can be found in human saliva?
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1answer
72 views

Why do eggs lack an endoplasmic reticulum?

Trueman's Elementary Biology book I found says that the endoplasmic reticulum is absent in eggs, but no reason is given. Why is it absent?
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1answer
12k views

Why is ATP the preferred choice for energy carriers?

Why is ATP the most prevalent form of chemical energy storage and utilization in most cells?
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5answers
3k views

Why are there no known animals with an odd number of legs?

In my 6th grade science book it is said that there are no three legged animals, and that no animal with an odd number of limbs exists. I checked Wikipedia and could confirm this: There are no ...
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1answer
40 views

What does uniprot consider “unambiguous” evidence for the subcellular domain of a protein?

Uniprot has annotation for subcellular location of protein domains. This topological domain information of proteins is under the TOPO_DOM flag. In most cases the ...
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1answer
42 views

Lysosome function [closed]

Does any cell have lysosomes in it? Or maybe there are other organelles that do the same function. I read about it a lot and I can't find a good answer.
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28 views

How do cell repair mechanism ratios change as they age?

I have seen that embryonic stem cells are shown to use homologous repair for double strand breaks rather then non-homologous end joining (NHEJ). [1] I am wondering if something also happens to a ...
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1answer
94 views

What were the first neural systems like?

I'm curious about the origin of the neural network. I'm thinking perhaps once life evolved beyond the single cell organism, it needed a simple neural network to coordinate those cells, and cell ...
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1answer
47 views

Which organs need to have fluid compartments in order to develop properly?

I am a student, slightly struggling with the new concept of fluid compartments. I know that there are two main types of fluid compartment, extra and intracellular fluid. I also read that most organs ...
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2answers
102 views

Role of microvilli in cell volume regulation

Does the presence of microvilli on a cell's surface ensure that it's more resistant to cell swelling or lysis in a hypotonic solution, as compared to a normal cell?
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2answers
103 views

Energy metabolism in Cancer cells

The TCA cycle intermediate Isocitrate dehydrogenase commonly undergoes point mutations in cancers. This allows IDH to reduce a-Ketogluterate to 2Hydoxygluterate, causing a reduction in pVHLs ability ...
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0answers
57 views

Is it possible to isolate cells harboring a specific DNA sequence?

Suppose on cell subpopulation harbours within its genome a specific DNA sequence that do not exist in other cell subpopulations. Is it technically possible to isolate such subpopulation ? and if yes, ...
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2answers
76 views

Mitosis versus Meiosis I: What's the difference?

At the end of mitosis, one cell has divided into two diploid cells. But at the end of meiosis I, there are two haploid cells. How are the two processes different to produce these two types of cells?
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1answer
102 views

If so many different hormones/molecules work by activating adenylyl cyclase, how do they have different effects?

It seems that many hormones and molecules work by activating adenylyl cyclase to convert $\text{ATP}$ to $\text{cAMP}$, such as adrenaline and glucagon. Both of these seem to bind to $\text G$ protein ...
3
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1answer
205 views

Reason for the source of fetal bovine serum

What is the reason that perhaps the most commonly used serum in labs is fetal bovine derived? Is there something about fetal serum that is particularly useful over say serum just harvested ...
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1answer
32 views

Cellulose - why is it fibrous and not granular?

I was reading a book where it said that the 1 - 4 Glycosidic bond of the Beta Glucose meant that cellulose is fibrous and not ...
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3answers
2k views

Does a man contain all the genes needed to make a woman?

This question is brought on by a Sci Fi novel I am thinking about writing. The plot device involves a colonist in charge of building a population on a new planet who loses his supply of embryos and so ...
2
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1answer
77 views

How does the pancreatic beta-cell know how much insulin to secrete in response to glucose?

How do $\ce\beta$-cells know how much glucose is in the blood? I know that when glucose enters a beta cell it triggers the cell to produce insulin. $\ce\beta$-cells trap glucose by converting it into ...
7
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2answers
84 views

Permeability of Plasma Membrane

I’m having trouble grasping why small polar molecules can cross the hydrophobic region of the membrane and not ions. Won’t the polar molecules be attracted to the watery extracellular medium and not ...
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4answers
686 views

Photosynthesis: What Powers the Splitting of Water?

The splitting of water is an endergonic (non-spontaneous) reaction, and thus would require energy (chemical work to be done) in order to happen. In Photosystem II, an enzyme catalyzes this splitting, ...
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1answer
31 views

What effect is seen when the extracellular concentration of sodium is increased? [closed]

I can't seem to figure out how this would effect the cell since sodium is not very permeable.
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1answer
74 views

Is the problem of cryonics only the pressure?

According to the pop-sci sources which I drew on from, the only problem with freezing whole bodies its that you can't conserve it without freeze-damage. If you were keeping a cold-blooded animal in a ...
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0answers
16 views

Amputation of part of the cytoplasm of the amoeba? [closed]

We ampute a part of the cytoplasm of the amoeba many times and we observe that amoeba is not divided This experience allows to deduce the cause of the division of amoeba Do that have relation with ...
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1answer
87 views

Is a nucleus more dense than the rest of the cell?

On the one hand, it seems like there's a higher density of 'stuff' in a nucleus, so it should be more dense. On the other hand, if it was more dense, I'd imagine that nuclei would 'settle' to the ...
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1answer
46 views

Hayflick limit and hair or nails

I am not a bio major but I have heard about Telomerese shortening in each cell division which leads aging and cellular death. I also read that Hayflick limit is about the number of divisions a cell ...
0
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1answer
32 views

How DNA programs the first cell in womb into a human [closed]

Sorry if you see me silly. I am just a programmer happens to be curious about biology... So far I understand how DNA make protein, how cell divides, how one composed of cells->tissues-> organs. ...
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0answers
23 views

Pathogenesis of type IV hypersensitivity

In hypersensitivity, as I understand it, a normal immune response gets excessive, misdirected or wrongly regulated to cause tissue injury. The various types determine the various ways in which the ...
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1answer
39 views

Are there differences in energy of glucose isomers?

There are many isomers of glucose, including galactose and fructose. Do they have different chemical energy levels, and why? What makes galactose and fructose useful compared to glucose, and would ...