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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How was the first ribosome theorized to have been made?

Seeing as ribosomes are what help perform the act of translation itself, and the blueprints for they themselves are in nucleotide sequences, how was the first ribosome theorized to have been made? ...
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298 views

Does GTP-γS (GTP gamma S) bind all GTP-binding proteins?

I've just read an article Rab10 GTPase regulates ER dynamics and morphology - Nature Cell Biology 15, 169–178 (2013) doi:10.1038/ncb2647. In this paper, to identify Rab proteins in ER, first they ...
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354 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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122 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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503 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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50 views

Spatial learning in microorganisms

Has there ever been an experiment performed that demonstrated a form of 'spatial memory' in a unicellular organism? I'm imagining something analogous to the classic 'rat in maze' experiments, but ...
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582 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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3answers
164 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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80 views

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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236 views

What's a good reference for choosing histological staining chemicals?

It's often difficult to find the appropriate or best stain to use when I want to examine a new type of tissue. I think that's partly because many histological techniques were developed a long time ...
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75 views

What is the fate of micronucleus DNA?

Micronuclei are cellular structures that are formed as a by-product of, usually, defective mitosis. The piece of chromosome in a micronucleus may, or may not contain a centromere and the DNA is ...
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515 views

Why do some internal organs regenerate?

I have been reading about the human liver and zebra fish heart muscle having the ability to regenerate. It seems to me that these organs have very little chance to become damaged or worn out. At the ...
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2k views

Which of the cell types commonly found in mammals has the greatest number of mitochondria?

This is basically a fun question, inspired by this answer on scifi.se. So, which cell type will have the greatest number of mitochondria? Obviously, I am talking about wild type, healthy individuals ...
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289 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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122 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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508 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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82 views

How are chromatids correctly segregated during mitosis?

In my book this is described as happening by kinetochores depolymerising from their attached microtubule spindle, then being dragged towards the spindle's centrosome by a dynein protein. I can ...
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358 views

Primary cilia: what cell types have non-motile cilia that migrate?

My understanding is that there are two broad categories of cilia: motile and non-motile (also called primary. Examples of the former include sperm flagella and the cilia of epithelial cells that ...
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90 views

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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90 views

number of RNA pol II molecules in a given human nucleus?

Does anybody have any estimate on the number of RNA pol II molecules in the nucleus of a given human cell? For example, how many RNA polymerase type II protein complexes would there be on average at a ...
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160 views

Is there a karyotype database for human cell lines?

I'm looking for the karyotype of a specific cell line. Some karyotype are well known, such as HeLa or some carcinomas, but some are very hard to find, such as LG2 (B cells). Is there a database ...
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RNA or ribosome, which one moves during translation?

During translation ribosomes decode the genetic information present in the mRNA and protein synthesis takes place. During this process which of those two does move, the ribosome or the mRNA?
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172 views

Can botulinum toxin be grown or kept from denaturing in an UNWRAPPED 50 pound hay bale?

Botulinum toxin is the neurotoxin protein created when botulism spores grow. The requirements for growth and/or for keeping the toxin from denaturing would seem to be very difficult to create in bale ...
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206 views

How can a ligand be an integral membrane protein?

My background is in mathematics, and not biology, so please bear with me. I am currently working on a project involving the effects of Epidermal growth factor treatment (EGF) on cell migration. I am ...
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306 views

Studying effects of alcohol on cells

I am wondering about the logistics of a simple experiment with say 3 types of alcohols, and various concentrations of each, with a control(s) I would like to research the effects of alcohol on ...
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1k views

Can proteins move outside cells?

I am trying to learn about basic cell biology, and have what is probably an extremely simple question. So this is how I understand it so far: Proteins are made from amino acids. This process is ...
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277 views

What advantage does an enzyme serve over catalysis by the addition of heat energy?

I understand that an enzyme lowers the activation energy, allowing the reaction to run faster, however I am not sure, how it may be favorable during the addition of heat energy. Wouldn't that lower ...
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415 views

Why are certain aneuploidies more common?

Certain aneuploidies such as trisomy-21 (Downs syndrome), trisomy-18 (Edward syndrome), Turner syndrome (XO) etc are more common than others. I had a vague thought that it is related to chromosome ...
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189 views

Do changes in an organism's cell modify the genetic information it uses for reproduction?

What I'm actually interested about is whether a modification in one cell during the life of an asexually reproducing organism affects its genetic information? Which cell's genetic information is used ...
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170 views

Does soap kill human cells?

I see many products, particularly hand soap and cleaning products, that claim to kill 99.9% or more of bacteria. This makes me wonder, if the chemicals are potent enough to break down bacterial cell ...
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284 views

Is this a grass cell?

I found this picture online claiming it was a grass cell. Clearly it is a cross section image but I was hoping you could tell me if this is actually grass, or something else if anything. Thanks!
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119 views

What is an operon?

What is an operon in a eukaryotic cell, and how does it regulate the expression of genes? I've already read Wikipedia, but it is not enough clear to me. Unfortunately my knowledge in genetics are very ...
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4answers
681 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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165 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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177 views

During the process of correcting mutations via gene therapy, is the defective gene removed?

Just recently started learning about gene therapy, many websites explain that the corrected DNA can be added to the genome using a vector and all that. I just don't understand what happens to the ...
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3k views

What is the H+ gradient in mitochondria?

I would like to understand what the term H+ Gradient means. I googled this question and found terms such as chemiosmosis and ion gradient being tossed around. I am very new to biology and I do not ...
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97 views

Synthetic biology using existing cells

I was watching the video at this link: http://www.bbc.co.uk/news/science-environment-17436365 The speaker says that a cell is taken and its original DNA content is stripped out and replaced with ...
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178 views

Why does a “cascade” of events happen during signal transduction?

I've been watching some videos on signal transduction and it says that because there are enzymes being activated by the signal, then there is a "cascade" which happens afterwards...I don't understand ...
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What type of cell do you start with in Meiosis?

Okay, I was learning about mitosis and meiosis in school and had a question. I know in Mitosis you first start off with a Diploid (2N) cell and then end up with two ...
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41 views

How are the physiological properties of mitochondria measured?

this is my first question on BiologySE. I am a Physics and Mathematics student currently doing a project on cell growth simulation. I am doing literature survey and I have a question about cellular ...
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130 views

Are There Exceptions to Animal Cells not Having Cell Walls?

In the January Issue of SciAm (discussing Haemophilia): When damage occurs to blood vessels, exposure of the blood to collagen in the cell walls and material released by the cells triggers the ...
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70 views

MHC restricted peptide

What is an MHC restricted peptide? I got this definition from wikipaedia, but cannot exactly extract what the phrase MHC restricted peptide means. MHC-restricted antigen recognition, or MHC ...
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462 views

Time spent in phases of cell cycle

I am looking for references to papers containing the time intervals spent in different phases of the cell cycle (ej., G0, G1, S, G2, M for eukaryotes) for different cells. In particular, I am ...
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1k 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
397 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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1k views

How does the Golgi Apparatus perform its function?

The Golgi Apparatus is an organelle with a great number of functions, I am particularly intrigued in the role it plays in packaging macromolecules and sending them to their target organelle or to ...
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1answer
132 views

Can methylation of a promoter induce gene expression in some rare cases?

Can methylation of a promoter induce gene expression in some rare cases? I've read somewhere that methylation of an intron can induce gene expression (eg. Igf2). How is that even possible? Thank ...
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2answers
46 views

Regarding cellular self-destruction

I heard and read telomere 'health' or 'length' ( if that's right ) has alot to do with cell 'health'. If telomere 'abilities' are 'restored' to a 'healthier' status then the cell it is in functions as ...
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151 views

Are fish roe unicellular?

Are roe (fish eggs, caviar, etc.) single cells? I have tried looking this up on google (sadly, to no avail), and I am guessing they might be multicellular (like bird eggs) or consist of one cell plus ...
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458 views

What percentage of a cell's volume is occupied by protein?

I was looking at one of David Goodsell's illustrations of a cell: And it seems to suggest a very crowded picture of the intracellular environment. Just how crowded are cytoplasms? What percentage ...