Questions tagged [meiosis]

Division of a diploid cell to produce four haploid cells for the purposes of reproduction.

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is my answer correct or incorrect? (test says it is incorrect)

the first cell has 16 chromosomes, after first meiosis, it has 8 chromosomes and 16 chromatids, right? but the test says it is an incorrect answer, can I argue about this
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Is the cell cycle applicable to meiosis as well, or just mitosis?

All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis). Is there an equivalent "...
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someone find out the difference between meiosis and mitosis so she studied how red blood cells undergo cell division. Is her method appropriate? [closed]

someone find out the difference between meiosis and mitosis so she studied how red blood cells undergo cell division. Is her method appropriate? If not, what could she do to improve her experiment and ...
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What is the mechanism of chiasmata terminalisation in meiotic prophase I?

There's barely any fresh literature available about how the chiasmata between the non sister cromatids of homologous chromosomes separate. I'm curious to know about the forces responsible for pulling ...
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Chiasmata and Adaptation

We know that during the crossing over of meiosis II, some portions of the paternal chromosome recombine with the maternal chromosome along the chiasmata. And the number of chiasmata varies. My ...
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Germ cells vs. gametes

Naively, I thought that germ cells are diploid (in diploid species like human/mouse at least). Then, germ cells undergo meiosis and become haploid. I thought this was the critical change that defined ...
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Which chromosome of the two contained in a haploid cell goes into the diploid cell after fertilisation?

I am totally new to biology and I have a very stupid question. In the typical representation of meiosis, haploid cells contain two different chromosomes, resulting from the crossing-over process. But ...
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How many of the four meiotic daughter chromosomes of a homologous pair can be recombinant via crossover?

In graphics I've seen, crossing over occurs between the "inner" two chromatids in a side-by-side arrangement of two duplicated chromosomes: This suggests that only two of the four meiotic daughter ...
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Why are the products of Meiosis 2 different?

In Meiosis I, 46 chromosomes crossover. These mixed chromosomes then split off into new cells. In these new cells, Meiosis II occurs, where these mixed chromosomes have their chromatids ripped apart. ...
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How can paternal chromosomes be present in an egg cell during meiosis I or crossing over, if fertilisation has not yet occurred?

I am very confused about crossing over. It is said that crossing over increases genetic variation as it is a combination of paternal and maternal chromosomes. However, crossing over occurs in meiosis ...
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Human somatic cells have 22 pairs of homologous chromosomes?

I am studying for my Bio class and I am stuck with questions that I came up with during this chapter of Meiosis. I understand that human somatic cell is made up of 22 pairs of autosomes and 1 pair of ...
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How quickly does recombination shuffle chromosomes?

For each pair of homologous chromosomes, one was inherited from the father and one from the mother. If there were no recombination in meiosis, one could then say that one of the chromosomes was ...
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What is the probability that a gamete will only contain father's chromosomes

As it is depicted in most textbooks, cross-over does not occur between the two "outer" sister chromatids. By independent assortment during Meiosis I, there is 1/2^23 chance that all father's ...
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Can men with Klinefelter syndrome produce chromosomally normal sperm?

Individuals with Klinefelter syndrome are XXY. Even though sperm counts are low some individuals can generate enough to be used in IVF and have offspring. Does this mean that when sperm are formed, ...
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Meiotic recombination hotspots

Im trying to find a proper and general file with chromosomal coordinates for meiotic recombination hotspots. I know that ucsc hgtables, has a table with recombination regions and their recombination ...
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My understanding of chromosomes and the processes related to them is lacking [closed]

I'm sorry for the incredibly simple question, I just can't seem to find any answers elsewhere online. I am a high school student currently studying for the upcoming AP biology exam, and recently I ...
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Possible combinations in the Meiosis' Telophase 1

As you might already know Meiosis is the process in eukaryotic, sexually-reproducing animals that reduces the number of chromosomes in a cell before reproduction $^{[1]}$ One of the reasons why ...
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Does the law of independent assortment apply to homologous chromosomes or alleles, or both?

My textbook is giving me two definitions 1st def: "random orientation of homologous chromosomes at the metaphase plate in meiosis 1." 2nd def: "alleles for one gene separate into gametes ...
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Is there random assortment in metaphase II?

First, a little notation. Call a the first chromosome from my mother and A its homologous partner from my father. ...
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Fertilization of the human egg- where does our centrosome come from?

Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can ...
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When in the cell cycle is the number of chromosomes normally reduced?

Page 96 of the Study Guide for Campbell Biology, 11th Edition has the following question: A reduction in the number of chromosomes per cell occurs a. During meiosis I b. During meiosis ...
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Which is the correct term haploid daughter cells or haploid parent cells?

Meiosis 2 begins with 2 haploid parent cells and ends with 4 haploid daughter cells (gametes). Gametes from the opposite sex can now merge together and fertilize. If I were to refer to a specific ...
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870 views

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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What confuses me about “homologous gene”

When I first encountered homologous genes I thought those genes are identical because the text book said so, and "homologous" meant the same knowledge. But as I studied along, it comes out that ...
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During what phase is the cell polyploid? [closed]

During what phase is the cell polyploid? Why is it polyploid at this point--what has happened to create this state and why is it important to the process?
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How long does each of the stages in meiosis take?

For each stages of meiosis (i.e. Interphase, Prophase I, ...), I wanted to know the time between each stages either in percentages or minutes. However, while I could find the cell cycle for mitosis ...
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What exactly happens during the crossover [closed]

My knowledge of biology is rather limited, but I think I have a grasp of some basic concepts. For me (as a person close to math) a chromosome is a sequence of elements from the set {A,C,T,G} of some (...
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Human ancestor reproduction after chromosome fusion

I read somewhere that human chromosome 2 is the result of 2 primate chromosomes fusing together somewhere along our evolutionary journey. This is why we have 23 chromosomes while other primates have ...
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What does the nucleus look like in S phase of Meiosis?

I was watching an animation video about Meiosis and this is what the video shows (pics attached.) It shows that before synthesis, each chromosome exists as single chromatid and then after replication,...
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Polyploidy, or why plants of different species can produce fertile offspring hybrids more frequently than animals?

This site says: Plants hybridize much more frequently and successfully than animals do. [...] Chromosomal doubling (polyploidy) occurs more frequently in plants and facilitates the fertility of the ...
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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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How would homologous recombination and mutations affect speciation?

I'm wondering how homologous recombination and mutations can affect how speciation can occur from one species (so that 2 will be created). I'm doing research and I found that different mutations and ...
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How do biologists determine the parents of a child

I am not well-versed in biology so this question might be wrong. As far as I understand meiosis, two germ line cells with 23 chromosomes each (one cell from the father and another from the mother) ...
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Can you use a cell in meiosis to create a karyotype?

Why might it be problematic to use a cell undergoing meiosis to create a karyotype?
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Why there is replication of DNA before meiosis?

It seems to me that, even without replication of DNA before meiosis, the homologous pairs can still do crossover, and then be pulled to opposite poles, directly forming 2 haploid gametes.
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Why does cell waste energy in meiosis, between meiosis 1&2

As far as I have learnt about meiosis I have read that anaphase 1 is followed by telophase 2 where chromosomes change back to reticulum.but in the very next stage i.e prophase 2 they again start ...
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Does crossover happen between chromosomes from grandparents?

Rephrasing question: does crossover happen after sperm and egg meet each other, but before formed fetus starts to grow? As I understand sperm and egg of human are haploid cells. That means this cells ...
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1answer
583 views

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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How is it possible for monosomies to occur?

I was taught in biology class that a cell dies if it doesn't have at least one copy of a chromosome "type". If this is the case, that means that: Zygotes without a copy of a specific chromosome (for ...
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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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Why does crossing over take place at all?

I already know that crossing over causes genetic variation. My question is that since DNA is a stable molecule, why would it undergo process like crossing over during which it becomes so unstable and ...
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Recombination frequencies

I have been learning about recombination frequencies, but an still getting a bit confused despite having gone over many of the links in Google regarding them. I was wondering if someone could verify ...
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No. of meiotic divisions to produce specific no. of seeds

If I want to produce 100 seeds. Then the no. of meiotic divisions is 125 which can be calculated by the formula x + x / 4. x = no. of seeds produced. How is this formula derived?
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If you start with 1 cell how many are at the end of meiosis? [closed]

If you start with 1 cell how many are at the end of meiosis? Can someone help me understand the process of what happens to the cells in the process of meiosis I and II
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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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Where did the nondisjunction occur?

A father with gene AC has a child with gene ACC. Where did the nondisjunction occur? (Meiosis I, Meiosis II, none of the above) I do not know because both Meiosis I and II have the possibility of ...
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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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what chromatin factors are the most potent supressors of meiotic crossover?

I think linker histone H1 is probably involved, but the literature is scant. What else prevents crossovers from becoming hyper-frequent during meiosis?
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How does chromosome number get halved in meiosis I?

In meiosis 1, it is said that chromosome numbers become halved in the two daughter cells. For example, in a 2n human cell there are 46 chromosomes. During meiosis 1, the cell will undergo interphase ...
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Question about genetic recombination

I am having some difficulty understanding a few things about genetic recombination, in part because of confusion from different diagrams in books. First of all, I wanted to verify whether I have ...