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Questions tagged [mitosis]

The eukaryotic process characterized by replication of nuclear DNA and formation of a second identical nucleus. Separate from cytokinesis.

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Can a dividing cell that skipped DNA replication become cancerous?

Let's assume that a cell fails to replicate its DNA during the S Phase of the cell cycle. Let's also assume that the appropriate CDKs are inactive (perhaps due to mutation or lack of cyclin proteins ...
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When two amoeba cells form from one amoeba, does spindle fibers form?

When two amoeba cells form from one amoeba, does spindle fibers form? Some sources say that spindle fibers do not form while an amoeba cell is undergoing cell division. If spindle formation does not ...
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How exactly does mitotic recombination help repair damaged DNA?

I understand the utility in crossovers during meiosis, but how exactly is mitotic recombination useful for dealing with DNA damage? If one sister chromatid is damaged, the other can supply a ...
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How are chromosomes counted at the end of mitosis in a plant cell?

Page 89 of the Study Guide for Campbell Biology, 11th Edition has the following question: A plant cell has 12 chromosomes at the end of mitosis. How many chromosomes would it have in the G2 ...
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Do chromosomes line up as pairs in mitosis or meiosis?

Here is a question from the book SAT II Success Biology E/M (where the SAT is the exam taken by the American high school students): Homologous chromosomes line up in pairs in (A) metaphase of ...
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With over 400 chromosomes, does mitosis in a species of butterfly happen in the same way as in humans?

The beginning of the Ars Technica article Gene editing crunches an organism’s genome into single, giant DNA molecule begins: Complex organisms have complex genomes. While bacteria and archaea keep ...
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Sucrose inhibit onion root mitosis? Why?

I am doing an experiment about onion root growing. I had put an onion in different solutions of $C_{11} H_{22} O_1$ in H2O —with the root touching the water—: 0,1M; 0,2M; 0,3M; 0,4M; 0,5M. The ...
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How does gene affect organs development in eukaryotic cells? [closed]

I'm totally new to biology and apologies if you find this basic. The central dogma insists that genetic information flows in this direction: DNA -> RNA -> proteins So far so good, it is very clear ...
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DNA replication during Mitosis

I am a bit confused. During Meiosis, DNA is replicated to form a cell with half the DNA and likely to have variations. But since the replication process of meiosis and mitosis are the same, why do DNA ...
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Unsure about definition of “n” and “C” values in mitosis

I am preparing for a Biology exam and I'm reviewing the "n" and "C" notation used in mitosis. My professor said that when the cell replicates its DNA in S phase of mitosis, we get twice the "amount" (...
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Mitosis in free nuclear divisions

When free nuclear divisions occur(for instance in endosperm formation in coconut etc)....there are many nuclei undergoing kartokinesis at a given point of time...so that means each karyokinesis will ...
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Can 12 mitotic divisions produce 6000 nuclei?

The following quote is from "Principles of Development" by Tickle & Wolpert: "After fertilization and fusion of the sperm and egg nuclei, the zygote nucleus undergoes a series of rapid mitotic ...
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Why does colchicine not affect the source plant itself?

Colchicine, being a mitotic poison that blocks spindle fibre formation, should affect its source plant. It should also stop its cells from dividing. So how do they grow? I think that there might be ...
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Cell organels during cell reproduction

When one studies cell division, usually the process is explained through what happens with the DNA of the cell, particularly, that in eukaryotes the nucleus dissolves. But what happens to the rest of ...
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Is aneuploidy/aneusomy only a problem for cell division?

One of my textbooks states that: "recent studies suggest that aneuploidy can be seen in upwards of 10% of human brain cells without any noticeable effects" I do know that trisomy 21 causes ...
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How does the spindle fiber find the kinetochore?

I am curious if anyone knows the exact mechanism of how exactly does the spindle fiber find the kinetochore? it certainly seems like a fairly non-spontaneous reaction for a spindle fiber to reach all ...
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During interphase, is DNA wrapped around histones?

Are histone proteins present around DNA in the nucleus during all of interphase (including G1) or do histone proteins only form later on when chromosomes are condensing into chromatids? Thanks in ...
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Why does abnormal mitosis takes place in the cells of tapetum?

I know that the tapetal cells present in the anther are binucleate. I also know this means that after karyokinesis the cell does not divide itself and instead form a syncytium. This occurs due to ...
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Purpose of intensive protein synthesis in G1 phase of mitosis

What is the purpose of intensive protein synthesis in G1 phase of mitosis, and what purposes do these synthesized proteins serve? Why are lipids and carbohydrates not synthesized intensively as well?
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MCQ - Events in the Mitotic cycle

The following question confused me at first However, I presumed that it must be in comparison to meiosis. In that case D would be correct. However, the correct answer is A. How can this be? I know ...
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How are germ cells not reduced in number?

If germ cells produce haploid daughter cells by meiosis and are thereby "consumed" (where there was a germ cell there are then 4 daughter cells), where do the germ cells come from? I asked my biology ...
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What is the purpose of two cell divisions in meiosis?

At the moment, my thoughts are that the two cell divisions are necessary for recombination to occur, although I am not sure. I cannot really see why technically, the chromosome from each parent cannot ...
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Separation of sister chromatids diring anaphase without Centrosomes in plant cell during mitosis

As in animal cell during mitosis sister chromatids are separated from each other during Anaphase by the pulling of kinetochore fibers toward their originating poles of centrosomes but as we know that ...
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How many cells are in prophase on this onion root tip slide?

In the following image, I have to identify the cells in the different phases (not counting the cells that are too faded to see), and it's fairly easy to identify metaphase, anaphase, and telophase, ...
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Why isn't meiosis II called mitosis (as the chromosome number doesn't half)?

Meiosis: a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores. Mitosis: a type ...
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Why do some organelle (like ER and Golgi complex) cannot be seen under microscope during cell division?

I have recently read in a book that organelles like ER (endoplasmic reticulum) and Golgi Complex cannot be seen under a compound microscope during cell division. Why does this happen, and where do the ...
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How can I determine where meiosis occurs in the life cycle of a plant?

To fill out this diagram with the mitosis, meiosis, and ploidy , we start with the definition that spores are haploid (N). Based on knowing that as the sperm and eggs are N, the gametophyte is also ...
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What is a centrosome?

I know that a centrosme is composed of two perpendicular centrioles, but the following sentences of Wikipedia confuse me: Interestingly, centrioles are not required for the progression of mitosis. ...
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Mitosis and Colchicine

I'm preparing for an Olympiad and while I was going through some of the old papers I found a question. I googled it but a lot of people have different answers to it. Please help. A student treats ...
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Reproduction or Cell division

Most of the cells in multicellular organism undergoes cell division through Mitosis. While most of the single celled organism reproduces through binary fission by mitosis. In both cases,the ...
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Why don't onion root tips show mitotic stages?

It was back in the winter that we did the Onion root tip experiment in college. We were able to see wonderful stages but now in this monsoon-autumn transition the root tips hardly show any mitotic ...
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Can cancerous cells reach the Hayflick limit?

This may be a stupid question, but I've been wondering. Each time a cell divides, the telomeres on the chromosomes shorten. If this goes on for long enough, the chromosomes will no longer have ...
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Can cell division be stopped during prophase?

There are three known checkpoints which ensure proper division of the cell. These are: the G1 checkpoint, also known as the restriction or start checkpoint or (Major Checkpoint); the G2/M ...
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From 46 human chromosomes, is each one from a single parent?

Humans have 23 pairs of chromosomes. Each chromosome in pair is homologous to another one in pair. Does this imply, that the entire chromosome in any cell is obtained from only one parent? I mean ...
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3 flaws of genes from the perspective of a programmer [closed]

Having a double helix structure seems like a waste of space. In programming you would have a single array and just before mitosis you would double the single helix. Having an exact copy of a cromatid. ...
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What are golgi blobs? [closed]

From a general google search I have come to know that golgi 'blobs'(also referred to as "golgi haze") are tubular vesicles formed during the interphase of mitosis. I would like to be reassured and ...
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What is the difference between the mitotic spindle and microtubules?

In mitosis, I understand that the centromeres line up on the spindle. I also know that the centrioles form microtubles between the centromeres during mitosis in the metaphase. But, are microtubles ...
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Formula for number of divisions required to form x number of cells (Mitosis and Meiosis)

In case of Mitotic Division, we say that if the total number of cells formed by mitotic divisions are $x$, then counting from the first cell onwards, we get $x-1$ divisions ($N$) $N = x-1$ This is ...
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Can a cell start a mitosis if it lacks energy or molecules to complete it?

I'm wondering whether a cell can start a mitosis if it lack molecules or energy to fully complete it. From what I'm reading on wikipedia the cell passes most of its time in the interphase in which the ...
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In cell division, are daughter cells identical?

I understand that after a cell replicates, there will be two daughter cells instead of one. But wouldn't one of them be the old cell that created the second one? The old cell having gone through G0, ...
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Do human somatic cells have 46 chromosomes all the time?

As far as I know, a human somatic cell has the cell cycle: Interphase and Replication (mitosis). In interphase, the cell has 2 growth phases (G1 + G2) and a synthesis one (S phase being in between ...
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Which steps occur in each phase of Meiosis and Mitosis [closed]

MITOSIS In mitosis am I correct in saying that the spindles attach to the centromeres at the end of prophase/prometaphase? (I read this in an answer to another question) MEIOSIS Does the ...
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Focusing on flowering plants, are there reasonable explanations why pentaploids would be more fertile than triploids?

For the genus Rhododendron, triploids are sometimes fertile but pentaploids appear to be often fertile. Once Rhododendron seedlings gets above the triploid level, aneuploids not near euploid appear to ...
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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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Where do most mutations come from, mitosis or meiosis?

According to this (old) paper there are 10 times more mutations during meiosis than during mitosis. One reason for that is that recombination often causes replication error and therefore mutations. ...
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How do nuclear membranes form during Telophase of Mitosis/Meiosis?

During Telophase, homologous chromosome pairs reach the poles of the cell with the help of microtubules. From there, nuclear membranes form around each new set of chromosomes. My confusion originates ...
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How many mitotic divisions do haploid cells undergo before fertilization?

Background This question is about human physiology and gametogenesis. A spermatozoid is not necessarily the direct "offspring" of diploid cell. Stated differently, a spermatozoid cell can be the ...
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DNA content doubling in interphase

Why does the DNA content of a cell get doubled in interphase? Why doesn't it become tripled or quadrupled? What's stopping it from doing so?
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Why doesn't crossing over happen in mitosis?

If there was crossing over in mitosis, then there would various nature of somatic cells. May be that's the logic, but what is the mechanism? Why are there no crossover events during mitosis?
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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 ...