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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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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122 views

Problems understanding membrane potential

I understand that membrane potential is the difference of the extracellular and intracellular ionic charges, due to their concentrations. We say that the extracellular space has a charge of 0 and then ...
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720 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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76 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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259 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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103 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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209 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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98 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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89 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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510 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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5k views

Which human cells have the longest and shortest lifespan?

Which cells in a human have the longest lifespan? Which cell has the shortest lifespan?
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95 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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100 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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86 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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62 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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768 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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173 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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62 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 ...
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253 views

Chromosome and chromatid numbers during cell cycle phases

A diploid cell in G1 has 6 chromosomes. How many chromosomes and how many chromatids are present in each of the following stages? Here is what I am guessing G1: 6 chromosomes ; 6 chromatids G2: 6 ...
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37 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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235 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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161 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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95 views

How extensive is CD47?

CD47 aka the "don't eat me" signal has recently been claimed to be expressed on all tumor cells. This doesn't seem to corroborate with other cell-biology experiments. On what other cells is CD47 ...
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48 views

Do non-enzyme catalysed reaction pathways exist?

Can their be a kind of chemical reaction pathway in a cell, that is catalyzed or regulated but NOT necessarily by enzymes? I could not find anything on Google. I have almost no background in biology, ...
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119 views

Mechanism of Muscle Growth

According to this video (sorry for the poor reference but it represents my level of understanding in physiology), muscle grow as a consequence of repairing micro-lesions. How are these micro-lesions ...
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91 views

How does a Na+/H+ antiporter drive osmosis in this “osmotic motor”?

This recent paper in Cell describes a cancer cell using osmotic pressure to move in confined spaces. The cell preferentially inserts Na+/H+ antiporters in the leading membrane. I want someone to ...
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375 views

Aerobic vs anaerobic respiration comparison

The following graphs compare glucose decomposition in yeasts (in anaerobic vs aerobic conditions respectively) My question is, why doesn't the first one look like a straight line as the second one ...
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148 views

Can in the case of multiple sclerosis (MS), a too high osmotic pressure in the nerve, lead to a high intracellular concentration of potassium?

Can in the case of multiple sclerosis (MS), a too high osmotic pressure in the nerve, lead to a high intracellular concentration of potassium, and also lead to 'pumping up' of nerve cells, which then ...
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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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992 views

How does water buffer a sudden drop in temperature?

A property of water is that it is slow to heat and cool. According to my biology book, some energy from an increase in temperature would spent breaking hydrogen bonds, so that temperature does not ...
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177 views

Improving transformation efficiencies- induce supercoiling?

From my limited knowledge of science, I know transformation can be one of the hardest step in cloning, and that a large amount of research/trial and error has been done to improve on this step. I've ...
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597 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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42 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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68 views

What is the mechanism by which lamins regulate gene expression?

The heterochromatin is generally localized at the nuclear periphery (also near nuclear lamina), whereas active genes are preferentially found in the nuclear interior. Children with ...
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301 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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464 views

Are there any multicellular forms of life which exist without consuming other forms of life in some manner?

The title is the question. If additional specificity is needed I will add clarification here. Are there any multicellular forms of life which exist without requiring the consumption (destruction) of ...
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229 views

What is MHC haplotype?

What is MHC haplotype? I did check out the wiki article, but did not understand. (I have not studied biology since last 8 years and now I am going through it because I need it for my research. So if ...
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1k 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 ...
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87 views

Name two reasons why it is impossible to determine a gene's nucleotide sequence from the amino acid sequence of the polypeptide

I can only think of one reason, which is because different codons can specify the same amino acids. However I am having trouble thinking of another reason.
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137 views

positive and negative feedback

I want to know more about positive feedback in gene regulation and to know the similarity and differences between positive and negative feedbacks.
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83 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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181 views

Breakdown of energy expenditure at the level of a single cell

The metabolic rate measures how much energy an organism expends over a unit of time. Its breakdown for the human body in terms of its functions is well documented : so much for the heart, for the ...
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169 views

How do detergents get in hydrophobic membrane interior?

According to Molecular And Cellular Biology (Stephen L. Wolfe), Membranes disperse almost instantaneously if exposed to a nonpolar environment or to detergents, which are amphipathic molecules ...
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832 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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312 views

What is our skin made up of?

Again, it is a basic question. What is our skin made up of? is it made up of many cells arranged in a systematic way or is it just like any layer say of a book?? what is the difference? where is the ...
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3k views

Why was the Davson-Danielli model rejected?

According to my textbook, Davson-Danielli's model of a phospholipid bilayer sandwiched between two layers of globular protein was incorrect. The nonpolar protein portions would separate the polar ...
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94 views

Trying to differentiate between the three muscle tissues with small pictures

For an assignment I have to differentiate the three types of muscle tissues in these three pictures . I'm having difficulty seeing the striations and branches etc. because the pictures are so small. ...
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121 views

Transmembrane Protein Problem

Problem A transmembrane protein has 1000 aa. The 5th aa is found on the external side of the cell membrane. It interacts with the aqueous environment outside the cell. Amino acid 90 is inside the ...
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Are there known downsides to removing UV mutation hotspots to prevent some skin cancers (Genetic sunblock)?

Khavari et al. recently demonstrated that a significant fraction of one of the major forms of skin cancer (cutaneous squamous cell carcinomas) are associated with a mutated KNSTRN gene (a protein ...