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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81 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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5answers
4k 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
42 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
44 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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0answers
35 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
114 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
51 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
113 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
105 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 ...
3
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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
357 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
120 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
216 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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47 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
98 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 ...
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2answers
95 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
950 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
34 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
75 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
17 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
114 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
59 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
39 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
24 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
62 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 ...
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0answers
23 views

Could drugs promoting angiogenesis be used as a treatment for burn victims?

From what I've learned from my textbooks and in class lecutures it seems that inducing angiogenesis for people with severe burns would be an excellent way to speed up the healing process. Is this ...
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1answer
39 views

Why is Bcl2 a good target for cancer therapy?

Bcl2 is a family of proteins that are involved in the inhibition of apoptosis in cells. My question is that what makes this anti-apoptotic protein useful in cancer therapies as opposed to focusing on ...
2
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1answer
34 views

How are cardiac cells stimulated by an action potential?

Why, and how, does the action potential of one cell in the heart stimulate an action potential in the next cell? I'm interested in an answer with citation.
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1answer
47 views

Why does a cell produce a lot of p53 protein only to later degrade it?

It is known that the half life of p53 is short and so does that play a role in the amount of energy the cell would need to expend to degrade all the p53? By that does the fact that the half life of ...
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1answer
32 views

why dna polymerase 3 requires a primer for replication [duplicate]

Why DNA polymerase 3 needs a primer to star replication.And whats happens when there is no AUG sequence on entire DNA.
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0answers
15 views

Arginine finger for regulating GTPase activity of heterotrimeric G-proteins as well?

I've seen video on iBiology discussing mechanism of Ras-Gap protein regulation of Ras protein (monomeric G-protein) involving an "arginine finger' from Ras-Gap for stabilization of intermediate in ...
3
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2answers
64 views

Are the ribosomes specific for each organism

If we removed one ribosome from human and we put it inside horse, would the ribosome perform the as it would in humans or it will not work or somewhere inbetween?
3
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3answers
237 views

Can/Have cancer cells be/been used in stem cell culture lines?

Since Cancer cells have unlimited growth potential, can they be induced towards totipotency and pluripotency? If so, can cancer cells be used in stem cell culture because of similar properties of ...
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0answers
30 views

Why don't the minus ends of microtubules shrink?

Is this because $\alpha$-tubulin is always in the GTP state? Or is it because $\gamma$-TuRC stabilizes the minus end?
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1answer
71 views

Is there any way to make protein pass through cell membrane?

Protein cannot pass cell membrane because it's a large molecule. Until now, is there any technique that can make protein pass through the cell membrane in vivo? I want to create a protein-drug that ...
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3answers
7k views

Was the mitochondrion or chloroplast first?

I still don't know if the mitochondrion or chloroplast was first? I've looked for it on the internet and in various books but haven't found anything. Does anyone have the answer and a theory which ...
3
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2answers
105 views

Question about proto-oncogenes and oncogenes?

My textbook says: Growth-promoting genes are called proto-oncogenes. Some can be changed into oncogenes by a point mutation that alters the ability of the proto-oncogene to be switched off. They ...
2
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3answers
512 views

How can I create a microcapillary for manipulation of single cells?

i'm working as a diy bio. I'm finding a way to create a micro glass capillary for picking up single cells. I see this video on youtube and would like to know what is the minimum I/O diameter if I pull ...
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1answer
96 views

What's the difference between tumor cells and host cells? [closed]

When you talk about cancer, is there a difference between tumor cells and host cells ? What is the role of immune cells ? in a nutshell ?
2
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1answer
229 views

How long can a human neuron live outside the body in a controlled environment?

Have there been any experiments that have kept neurons alive (stationary), without preserving methods such as freezing? If yes, then how long were the cells kept alive for?
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0answers
37 views

Mechanism of Octoxynol-10 as a preservative in vaccines

I noticed that the Fluarix Quad flu shot this season contains Octoxynol-10 rather than Thimerosal as a preservative. I am not expert in this area, so I did a Google search of "Octoxynol-10", and ...
2
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0answers
34 views

How do human cells respond to mechanical pressure such as heel contact during walking?

Basically, I'd like to do a full accounting (inventory, assets, liabilities) of a human cell under mechanical pressure. For example, if in steady-state, does the cell consume more or less energy ...
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0answers
15 views

Heteroplasmy in different tissues

I have only started reading the substantial body of research on heteroplasmy. I was curious if anyone knew of attempts to measure the somatic cell mtDNA mutation rate, to see if it differed from the ...
18
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2answers
47k 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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0answers
32 views

What does high CD4 level means?

I was going through this webpage and I found the following lines: We hypothesised that despite unimodal distribution of CD4 co-receptor on naïve CD4 T cells they are not homogenous in their ...
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0answers
29 views

UACC-462 cell culture

UACC-462 is a pancreatic cell line established in the University of Arizona Cancer Center (UACC). The cells are available from ATCC and there is the instruction for culturing UACC-462. M-41 medium. ...
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0answers
19 views

What is the significance of 9+2 arrangement in flagella?

Why eukaryotic flagella have 9+2 arrangement .? What is the significance? a 9+0 flagella should have worked the same way .
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0answers
33 views

How is flagellar movement controlled?

How does a cell control the movement of flagella? Both the rotatory movements and sideways movements helps the cell to move. How are these flagellar movements controlled ? It is through the regulation ...
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1answer
60 views

Why is it important to have a restriction point? (G1-S phase control)

Why have eukaryotes evolved to control G1-S phase? Surely if you could control G2-M phase very well, you will not get an excessive proliferation? Thanks for your help.