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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Using ion-exchange chromatography to purify DNA from a cell extract - Is DNA more negatively charged then RNA?

When applying this method we have a glass or plastic column of resin which is positively charged. Then we pour cell extract into the column in order to capture the negatively charged particles which ...
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2k views

Why does alcohol cause the hemolysis of RBC in a large proportion?

I had today an experiment that we put 95% alcohol to the blood which made it completely transparent so hemolysis must have occurred. I started to think about the reasons. I think that this is because ...
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878 views

“Acellular” designation for organisms

Why do some biologists refer to single-celled organisms such as Amoeba and Paramecium as acellular (i.e., without cells) rather than unicellular (i.e., one cell)?
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Why can't a human regenerate limbs like some other species?

When a person's arm is amputated, the arm will no longer be able to grow back. However, in salamanders, the arm actually grows back. In comparison to a human, what is really happening to the cells ...
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169 views

Number of spindle fibres during Metaphase?

During metaphase, the chromosomes are arranged on the equatorial plate and are attached to spindle fibres. After S phase, can the cell be said to attain the configuration of 4n? Also, during ...
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50 views

What is the title of Darwin's paper on cellular structure?

I read somewhere that Darwin wrote a paper that dealt with cellular structure, but I've been unable to find the title or contents of the paper because Darwin wrote such a volume of material. What is ...
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47 views

Similarities Between Cells?

Which of the following are usually identical between a lung cell and a brain cell, from the same person, assuming that they are normal (non-cancerous) cells? Circle your choice(s). ...
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2k views

Multi-nucleated cells: advantages and examples?

This question arises because I saw that monocytes and leukocytes are commonly called 'mononuclear cells' in the scientific literature. The implication of course being that other immune sub-types are ...
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615 views

How do cells “know” what “type” to differentiate into?

I have been reading about Townes and Holtfreter's work in 1955, in which cells are dissociated from a blastocyst in an alkaline solution then mixed together and spontaneously reaggregates based on ...
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382 views

How are different types of cells created from zygote?

In the process of mitosis that starts from zygote, how do different cells appear? What happens that some cells become one type and some another? For example, is there a cell that divides into a ...
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281 views

Is there sufficient evidence that human cells are not intelligent? [closed]

Being structurally composed of one or more cells, which are the basic units of life. Yet within a cell, there seems to be the same behaviors that define life: Regulation of the internal environment ...
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113 views

Creating a cell, not from another cell. Will it be possible?

If some time in the future, we can know exactly what a cell (for example simple prokaryote bacteria) contains, (I mean, exactly which molecules, the shape of them, the density of each, everything), ...
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365 views

Does DNA contain information beyond protein synthesis?

It's well known that genetic information is stored in DNA. As far as I know, DNA only has information at the protein level. What about higher levels, such as organelles, cells, tissue, organs? Is ...
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201 views

Why is most tissue cellular?

Most tissue is comprised of cells. Why? It would seem inefficient to have so many individual nucleus, membranes, etc.? Specifically: Not all tissue is cellular. Much tissue is extracellular matrix. ...
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733 views

Methods of nuclear transfection - nuclear transport

I am reading through the ENCODE papers, which is taking me well out of my comfort zone in terms of modern laboratory techniques. At the risk of asking a question which may well be thoroughly answered ...
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Is there an advantage to linear chromosomes?

The DNA copying enzymes have a hard time working to the end of a chromosome. For circular chromosomes this is not a problem, since there is not a sharp 'end'. However, for a linear chromosome, without ...
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97 views

What are the different, high-level programs along which a eukaryotic animal cell can follow?

What are the different, high-level, disjunct (mutually exclusive at one particular point in time) programs or pathways along which a eukaryotic animal cell can follow? Examples of programs would ...
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919 views

How long can a unicellular organism live without nutrition? What happens after that? Does it depend on the domain?

Say I have three unicellular organisms: a eukariote, a bacterium and an archaeon. If I cut off nutrition from them at the same time, how long will it take for them to die? What will their death look ...
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33k views

How many human cells are there in our body, on average?

How many human cells are there in our body, on average? Wikipedia says 1013: Bacterial cells are much smaller than human cells, and there are at least ten times as many bacteria as human cells in ...
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865 views

Under what circumstances will a human neuron divide?

I read somewhere that a mature neuron loses its ability to divide, except for very specific situations. I was unable to find the description of those situations. What are they? (I'm sorry I'm not ...
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Are there verbs for “undergo mitosis” and “undergo meiosis”?

From my experience on SE sites, I believe this is the right site to ask this question under "terminology". I've been trying to find out whether English has one-word verbs for "undergo mitosis" and ...
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1answer
109 views

When should endocytosis inhibitors be used in cell binding assays?

I'm beginning to do some cell-binding assays and I would like for my proteins to not be endocytosed by my mammalian cells. Typical suggestions are for the cells to be kept on ice and that the binding ...
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910 views

Does every mitochondrion in a cell contain the same DNA?

I know that mitochondria of eukaryotes have their own DNA, more similar to that of bacteria than to the rest of the cell's DNA. I also know that a cell can have plenty of mitochondria, and I ...
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147 views

What gaseous substances do humans emit?

Other than CO₂ and Methane what other gases do humans produce or emit? For example, does skin decomposition, or aerobic respiration emit any special gases that people don't normally realize or know ...
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548 views

Why aren't mitochondria and plastids considered symbiotes of eukaryotic cells?

Mitochondria and plastids have their own DNA, their own membranes, and their reproduction is not tied to the reproductive cycle of the host cell. However, they are considered to be organelles rather ...
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150 views

How much energy does a cell expend maintaining its contents?

In software engineering, an analogy is sometimes made using biological cells. I would like to know whether it has basis in fact. People say (Alan Kay was first) that "objects" in software should be ...
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145 views

Free-flowing cells and those that are stuck together?

I've been thinking about the development of an embryo from the zygote stage. How is it that when cytokinesis takes place at that stage, the cells all stick together in a little ball, but later in ...
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121 views

How are synaptic vesicles brought to the synapse?

I'm reading about how synaptobrevin is used to identify synaptic vesicles for tethering near the synaptic cleft. Since neurons have a synapse and dendrites, I'd like to know how exactly the vesicles ...
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849 views

What is itching?

What exactly at the molecular level is itching? What physiological function does itching serve, if any? I cant remember the reference but a PLCb3 null mice lost the itch phenotype, so presumably it is ...
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119 views

Macromolecule levels in daughter cells after fission

When a prokaryote undergoes binary fission, how are the non-DNA macromolecules distributed between the two daughter cells? This is motivated by comments on a previous question and a G+ discussion. I ...
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242 views

Cell proliferation limit and senescence of embryonic stem cells and fibroblasts

I am trying to understand the importance of proliferation limits and cell senescence. In particular, I would like to compare the proliferation limit of Embryonic Stem cells (ES) and fibroblasts (which ...
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332 views

Computational/mathematical models for predicting phenotype from genotype

Karr, Sanghvi, et al. (2012) propose a whole-cell computational model for predicting phenotype from genotype in Mycoplasma genitalium. Their model simulates myriad cell processes such as DNA ...
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540 views

Lifespan of connective tissue cells

This post is regarding a follow up on my initial post on "Properties and life cycle of chondrocytes and tenocytes". I am elaborating on my question on the lifespan of tenocytes and chondrocytes. ...
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365 views

Intrinsic apoptosis in erythrocytes

With a lack of mitochondria, can red blood cells perform intrinsic apoptosis and do they have another way of generating cytochrome c to attach to a CARD domain and assemble the apoptosome? Or are ...
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557 views

Is collagen supplementation useless?

When collagen is digested is it broken up into usable components that the body can use to produce its own collagen? What evidence is there that supplementing with collagen type I & II etc.. can ...
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How do archaea relate to eukaryotes and bacteria?

I've read that they all share some genes, internal structure, and behaviour with each other, but with different degrees of overlap depending of what the function is. E.g., archaea have some eukaryotic ...
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37 views

Where can I find a transcriptome of a normal uveal melanocyte?

I am looking for a database where I could find a transcriptome (say obtained with a microarray analysis) of one (or ideally many) normal uveal melanocytes ?
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191 views

Significance of basal lamina for outer layers of epithelium

In stratified (not pseudostratified) epithelia such as the epidermis, what purpose does the basal lamina serve for the outer layer cells which do not even stand in contact with it? Also, how do these ...
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453 views

How fast do different organs turn over cells?

It is said that the human body turns over all cells or molecules in 7 year cycles. This is not quite correct, because there are different organs changing at different speeds. My interest is what is ...
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178 views

Regarding TIMP and MMP enzymes

Are there substances that can promote TIMP enzyme production, or MMP enzyme production or supression in tendons? Are there medical tests that measure quantities of MMP and TIMP enzymes in tendons?
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Can NSAIDs impact negatively the healing of tendons?

There are a number of articles regarding NSAIDs having a negative effect on healing conditions like tendonosis and tendinitis. From what I understand the channel through which they reduce inflammation ...
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1answer
906 views

Is there a relationship between efficiency of cellular metabolism and warm-blooded-ness?

My BIO 101 book states that when human cells convert glucose to ATP, the process is only approx 35% efficient, and much of the potential energy is lost as heat. However, that heat is useful to us in ...
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164 views

Which cells are responsible for the extracellular matrix remodeling?

I am studying a case of tendinopathies induced by an alteration of how the extracellular matrix is being remodeled. From my understanding there has to be a careful balance of MMP (metallproteinases) ...
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1answer
506 views

Are the cytosol and extracellular fluids electrically neutral?

I've found several sources that state that overall, the cytosol of a cell is electrically neutral. The extracellular fluid is also purportedly electrically neutral. How can that be when we have ...
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32 views

What metabolically happens when an egg fuses with the nucleus of a somatic cell

In stem cell biology, it is recognized that embryonic stem cells are transcriptionally inactive for the first 3 days of development. However, during somatic cell nuclear transfer, the nucleus is ...
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Macrophage pathogen fixation

Overly simplified, macrophages recognise pathogenic patterns and endocytose anything that matches them. That also works on bacteria, which are quite often very mobile. What if a bacterium was just ...
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2k views

Is the eukaryotic nucleus composed of a single or double membrane?

I know that it is usually considered a double membrane like those surrounding mitochondria and chloroplasts, but I read a review that stated "according to topological details it is actually a single ...
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1answer
17k views

How to store vegetables in the refrigerator: In plastic bags or not?

My wife and I are having a debate similar to this one: I claim that it's better to take the fresh veggies out of the bags and put them in the crisper with humidity control because: That's what the ...
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1answer
377 views

How similar are Circulating Tumor Cells and Cancer Stem Cells?

Circulating Tumor Cells (CTCs) are linked with metastasis and their presence can be used to indicate the onset of metastatic cancer. Likewise, the Cancer Stem Cell (CSC) hypothesis suggests that ...
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How do nuclear receptors locate each other to form a DNA loop?

Nuclear receptors can influence transcription far up- or downstream from their own binding sites by looping DNA (Rubina et al.; J Mol Bio 2004). I am not sure how exactly the receptors first attach ...