Tagged Questions

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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Simulating Cell differentiation

I'm a computer programmer deeply interested in Biology. I wish to write a computer simulation for cell differentiation. I understand there will be seemingly impossible challenges in doing this. But ...
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1answer
308 views

Are there records of monozygotic twins in which one experiences androgen insensitivity syndrome

I have given my high school biology students the thought experiment of "What would happen if a researcher induced twinning of a female zygote and then replaced one of the X Chromosomes with a copy of ...
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1answer
123 views

Are there oligocellular organisms in nature and, if so, what are they like?

I'd think protozoans can be oligocellular, but I haven't found any examples, and I'm curious to know what is the minimum number of cells an organism can have other than a single cell.
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1answer
72 views

Experiments in vitro vs those with dead organisms and fixated tissue

Does the term in vitro necessarily imply that the organism/organs/cells of study are dead? If not, is there an alternative latin term to refer to studies of dead biological matter ? (e.g. in ...
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1answer
571 views

How are lysosome membranes protected from the attack of hydrolases?

Lysosomes are a bit like the suicidal bags of cells. They help to clean cells, have an acidic pH and contain a large number of hydrolyzing enzymes. But why don't these hydrolyzing enzymes attack ...
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1answer
217 views

Would two species of yeast with similar genome sizes have the same number of genes or chromosomes?

Similar organisms generally have similar genome sizes. Given this, would two species of yeast have the same number of genes and chromosomes? Edit: Fixed with thanks to @daniel-standage
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2answers
217 views

Do any cells change in size or mass as mammals grow?

That is to say, are there cells that, between infancy and adulthood, get larger? Or is all growth done entirely via cell division? I'm wondering if it is safe to assume that the approximate number ...
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1answer
62 views

In a human, what non-germline cells have the highest/lowest mass?

I'm just curious which cells are largest/smallest in the human body other than sperm/ova.
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1answer
111 views

Where does an organism store reserves of amino acids?

Where does an organism store reserves of the amino acids it needs to build various proteins it needs -- in the liver ? in the blood ? in every cell ? Thanks
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2answers
337 views

Why do living organisms replicate itself or procreate

Why do living organisms spontaneously replicate itself or "procreate" (my understanding is that it does). From a uni-cellular and micro-organism point of view. Is there some sort of stimulant in the ...
5
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1answer
378 views

How to Design an siRNA Experiment?

I'm going to undertake an siRNA experiment soon, but I have only read about them. I want to address the role an enzyme plays in processing a protein. From what I understand, I will need to pick two ...
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4answers
1k views

Does pheomelanin have a useful biological function?

Melanin is a natural pigment that is categorized into two main forms, eumelanin and pheomelanin. It's well documented in the science literature that increased eumelanin levels reduces the risk of ...
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2answers
845 views

Advice on Cell Biology texts by Alberts

I am currently reading "The Chemistry of Life" by Rose. It's a great book (to me as a lay reader at least) and an interesting topic so I am interested in pursuing some of the further reading he ...
5
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1answer
388 views

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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2answers
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 ...
3
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1answer
647 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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2answers
1k views

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 ...
6
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1answer
126 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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1answer
46 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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0answers
48 views

Patch-Clamping Neurons Resources

Are there any lectures available on Patch-Clamping? Were can I find a mathematical model of Patch-Clamp? (that can be easily implemented in matlab). I have found some step-by-step protocols on ...
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1answer
46 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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1answer
1k 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 ...
6
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2answers
409 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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2answers
261 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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1answer
190 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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2answers
108 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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1answer
294 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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2answers
166 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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2answers
555 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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2answers
2k views

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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2answers
90 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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1answer
666 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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2answers
27k 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 ...
4
votes
2answers
485 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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3answers
1k views

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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0answers
68 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 ...
8
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1answer
673 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 ...
6
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3answers
133 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 ...
8
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1answer
387 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 ...
8
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1answer
107 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 ...
5
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1answer
91 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 ...
6
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1answer
114 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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1answer
683 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 ...
6
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1answer
115 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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1answer
171 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 ...
6
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1answer
275 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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1answer
398 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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2answers
234 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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0answers
101 views

Properties and life cycle of chondrocytes and tenocytes

Questions regarding chondrocytes and tenocytes: Do these cells replicate, or are they regenerated from mature stem cells? How often are these cells regenerated? How long do they live? Do they ...
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1answer
467 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 ...