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25

Isn't there a possibility that cell division will result in a daughter cell with no mitochondria? Yes, there is always the possibility. However, there must be a strong negative selection pressure against eukaryotic life that cannot achieve the proper partitioning of mitochondria, so you can imagine that there are mechanisms in place to prevent this case. ...


13

In addition to S Pr's excellent example, I wanted to point out that some very recent research describes some special behavior in oocyte development specifically related to mitochondria selection. Here's a easy-to-read version: https://www.sciencedaily.com/releases/2019/05/190515131741.htm Here's the original version in Nature: https://www.nature.com/...


11

Your individual questions here are reasonable enough - although you could do a bit better at knowing some more details of the systems you are dismissing as 'flawed'. However, I think the bigger problem is your overall approach, which seems to be to make analogies between human-made computers and biological systems and then critiquing the 'missing' parts from ...


11

A typical animal cell has 1000-2000 mitochondria. From a statistical point of view, assuming a random distribution of the mitochondria and that the cell splits in half, the probability of having 0 mitochondria is (1/2)^1000 or 9e-302. This makes it an impossibility for all practical purposes. With enough mitochondria, a process to ensure the cell splits ...


9

This is the data for a few cell types: Cell type Total G1 S G2 M Ref ---------------------------------------------------------- Neuro2a 9 2 5 1.5 0.5 [1] Hela 16.2 7.7 7.2 0.8 0.5 [2] A549 18 7 7.5 2.5 1 [3] MCF7 21.3 9 9.3 ...


8

In programming, if you need to ensure your data has integrity, a single array won't do. We have cyclic dependency checks in programing to determine if the data is corrupt. We have hamming codes to permit detecting a fixing one bit corruption. If we want to really fix multi-bit corruption, we need at least one copy of the data. Lossless compression ...


8

Colchicine is an alkaloid and a secondary metabolite of the plant- a crocus, primarily functioning to protect the plant (like, from consumption by herbivores). WHY COLCHICINE DOES NOT AFFECT THE PLANT: It is transported far away from its site of production to the tissue storing it so does not come in contact with normal metabolically active plant cell ...


7

If the question is about the one and only most important difference between mitosis and meiosis, then the answer "meiosis reduces ploidy" is probably correct. But if the list of important differences is open, it would be critical to add that mitosis generates identical cells (identical to each other and any ancestral cells, barring rare new mutations), while ...


7

So in mitosis, the cell has to split itself into two cells; each daughter cell has a functional genome that may again split into more daughter cells. The cell replicates the DNA before dividing, so the error in replicating 3x or 4x is that upon division, the daughter cells will have more DNA than the initial cell, and every generation will have more DNA than ...


6

Tumors can be benign (they don't bother you at all eg: a mole which does not change) and malignant (also called cancer). The difference is based on:- Degree of differentiation - How much the tumor cells resemble the normal cells Rate of growth - In general (over generalised) benign tumors are slow growing while malignant tumors are fast growing Spread to ...


6

Errors in division occur all the time and can show up in any dividing cell; this is, of course, important for cancer biology. If one of my cells replicates oddly right now it likely won't matter since it's only one out of trillions, but if that happened at a very early age in development it could be present in many if not all of my cells. Identical twins ...


6

Mature, differentiated neurons do not divide (undergo mitosis), but apparently there is a small population of self-renewing neural stem cells in adults that can produce new neurons. Neurogenesis predominantly occurs in the subventricular and subgranular zones of the brain. Peripheral nerves can regenerate along its axon as long as the endoneurial tube and ...


6

Short answer The spindle is made up of microtubules Background From Nature: Spindle fibers form a protein structure that divides the genetic material in a cell. [...] At the beginning of nuclear division, two wheel-shaped protein structures called centrioles position themselves at opposite ends of the cell forming cell poles. Long protein fibers ...


5

Telomeres do not "cause" ageing as such - although you are right that they limit the number of times a somatic cell can divide. Each time a cell divides the chromosomes are replicated in an imperfect way, and as such a small amount of DNA is lost from the end of the chromosome during each round of cell division. Telomeres are just extensions to the ...


5

The chromosomes copy at S phase. So S/G2 checkpoint up to early anaphase has 2n. You are on the right track to understanding the cell cycle, important to note the differences between homologous chromosomes (homologous pair) and sister chromatids, while understanding ploidy. During S (synthesis) phase which occurs between G1 and G2 , all the somatic DNA ...


5

At the start, all the cells are 2n, diploid cells. By far the largest difference between meiosis I and mitosis is that mitosis results in genetically identical, diploid somatic cells. Meiosis, in it's entirety, results in gametes of haploid genetic information, but the genetic information is not identical due to crossing-over events that happened during ...


5

Well, in my opinion, the entirety of the meiosis is a process (reproduction of sex cell) in which two levels of division occur, it's all kind of one process. Though meiosis II may seem to have many similarities with mitosis, meiosis II can only occur with sex cells, to my understanding that is the main factor which differentiates meiosis I and II from ...


5

Cell cycle can be divided into two phases: 1. Interphase 2. M-phase(Mitotic phase) Note: M-phase can also mean Meiotic phase but it is not the full form of the acronym. So M-phase in mitosis has four phases: Prophase Metaphase Anaphase(your answer) Telophase A mitotic cycle: The rest of the options: B. Cytokinesis Cytoplasmic division begins ...


5

To answer the numbered questions: In general, neurons never divide by mitosis. However, I believe you may have unintentionally misphrased your question; there are functional neural stem cells in the adult human brain as well, and these are believed to give rise to new neurons throughout the lifespan of an individual. They have only been found in specific ...


4

Based on T Abraham's answer, a hemocytometer would work. However, a hemocytometer requires a microscope, but if you are in a cell lab, you probably have access to a microscope. I would recommend using mammalian cells instead of bacteria, they're larger and easier to see, and more relevant to human health. If you're interested in liver toxicity in particular, ...


4

Great idea! It seems that this research has been done before and your hypothesis is correct, but testing a wide variety of alcohols and testing your hypothesis for each one of them would be a great project. Now, to do this, I would expect you would need to check the growth of the cells after certain periods of time. How would you do this? Well, the best ...


4

Different cancers divide at different rates. One way to qualitatively visualize this is observe hair loss in patients who are undergoing chemotherapy. Commonly, a drug like cisplatin will be administered which will cross-link DNA, inhibiting cell division by activating apoptosis. Tissues which are killed most readily by cisplatin are those which are dividing ...


4

In case of gametogenesis (let us talk about spermatogenesis) gametes are formed from meiotic division of Primary spermatocytes. In Primates Primary spermatocytes are cells that that are formed from mitotic division of B spermatogonia (which is another class of germ cells) which inturn are formed from mitosis of Ap spermatogonia which arise from mitotic ...


4

Amoebas undergo binary fission, which is a much more simplistic process than mitosis. In binary fission, the duplicated chromosomes simply separate as the cells is pulled apart. There are no spindle fibers used in this method of cell division.


3

For assaying effect of alcohol on cell growth:     Prokaryotic Cells Take ~5ml medium (LB for E.coli) in test-tubes/plastic tubes and add appropriate concentration of alcohol(s) in these. Inoculate 1% bacteria from a starter culture (OD~0.6) After different time intervals or a fixed time point take some culture, dilute and spread plate ...


3

I think you should start with immortalized cell lines and so in vitro division rates by perfect conditions. This is easier to measure than in vivo division rates. E.g. HeLa has a division time of 23 hours. MDA-MB-231 and A549 division times are around 28 hours. Growth of HeLa Cells Comparative Analysis of Dynamic Cell Viability, Migration and Invasion ...


3

Colchicine inhibits the formation of the microtubules by binding to tubilin and rendering it unavailable for the polymerization. Thats why the cells get arrested in the metaphase and can not go on further in the cell cycle and divide. For chromosome studies this is very useful since this is the phase where the chromatin is most condensed and can be viewed ...


3

First off this is called genetic mosaicism and indeed mitotic recombination is a contribution factor. Mitotic crossover events involve the exchange, by homologous recombination, of regions of chromosomes. 60% of homologous recombination events might occur during G1 and 40% of those event occurs after chromosomes are replicated (see this paper). For twin ...


3

If you are thinking of a process like meiosis but followed by DNA duplication, the problem is that this would create daughter cells that do not have the same genome as the parent cell. The diploid genome of a sexually reproducing species' cell has different alleles of the same locus. If the cell replicates itself by passing one chromatid to each daughter ...


3

Question is two years old, and the answer is approx 20 yo, but I believe both are still pertinent: According to Jared Diamond on pg 12 of his Harper paper version (1993 -- but reissued in 2006) of The Third Chimpanzee, we replace intestinal lining epithelium every few days, urinary bladder lining every two months, and replace every red blood cell about every ...


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