Tagged Questions

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

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Do all species have asymmetric female meiosis?

In all the examples I can think of, (mostly vertebrate), female meiosis, or oogenesis, only haploid gamete is produced while the other cell divisions result in polar bodies. While male meiosis results ...
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Do the eggs for larger litters come from the same meiosis events, or different ones?

There are some species of animals that give birth to more than one pup at a time. In these species, are the fertilized eggs all from one or a limited group of meiosis processes, or are they from ...
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Study case of the inheritance system of Oenothera

I've been told some interesting facts about oenothera. Apparently in this species some lineages have been through some translocations and in results to these translocations and in consequence, some ...
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tetrads in meiosis are held together by what

This is from SAT subject biology test practice question. The answer it gave me was both chiasmata and centromeres. I can understand they are held by chiasmata but why also centromeres? I looked it up, ...
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Meiosis vs. Mitosis

Meiosis is a type of cell division that reduces the chromosome number from 2n to n to make gametes viable for reproduction in humans. I know that during meiosis, there is independent assortment and ...
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Why does the chance of having a baby with Down's syndrome increase with the age of the mother?

Down's syndrome occurs when either the egg or the sperm cell contain on extra chromosome 21. To my understanding, women are born with all the egg cells in place already, so there's no further cell ...
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Interpreting graph of mitosis and meiosis

Note : Consider the y axis as 1,2,3,4(not 2,3,4) and x axis as time. Roman numerals should be considered from I-X ( some are not correct here ) Which stages show mitosis? My answer : III-V Which ...
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Distinguishing between mitotic metaphase and metaphase II of meiosis

I'm sorry if this seems like a silly question, but I was brushing up on some cell cycle dynamics and realized that everyone was talking about the differences between metaphase I and II, and since ...
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Division of Polar Body

The first polar body formed after meiosis-I is completed in oocyte, may or may not divide. Why is the statement that "it may or may not divide"? Is it random ?
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Need of X or Y chromosome protein after meiosis

After meiosis each spermatid get either the X chromosome or the Y chromosome. I know that the 4 spermatids formed from 1 spermatogonia are connected by cytoplasm and so the proteins made by X or Y ...
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2answers
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Why did Fair Meiosis evolve?

How and why did Fair Meiosis evolve? I can hardly think that it provided a fitness advantage to the individual carrying the mutation. Why would it? Or did it evolve through lineage selection? Or was ...
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Randomness in living systems

The point of my question is not to talk about events that are uncontrolled by living organisms. My question is about controlled randomness, or I'd like to say adaptive random process. Process that are ...
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396 views

Do the four cells produced by meiosis each divide into four cells again?

In the beginning of meiosis, there is one cell. During meiosis, 1 cell divides into 4 cells. Does each of these 4 cells divide each into 4 more cells?
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Coiling of chromatids during cell division

What is exactly coiling of chromosomes? I just heard about the names i.e paranemic, plectonemic, orthostichious, anorthospiral. I have ecaxtly no idea of what phenomenon is this. Also what type of ...
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1answer
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What are centromeres *really*?

I've gathered that a centromere is a a region* where the DNA is bundles up even tighter (around protein different to Histone) and chromatids are 'joined'. However I'm still mostly in the dark ...
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1answer
119 views

Are any organisms known to use meiosis I to create non-identical offspring asexually?

So, there are numerous species of animals who use parthenogenesis, but to my knowledge the reproduction is clonal. That is, the offspring are identical to the mother. Are there any documented cases ...
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1answer
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Can IVF decrease the probability of trisomy in the fetuses of older mothers?

Is trisomy mostly due to complications with fertilization? If so, does in vitro fertilization reduce the probability of trisomy for the fetuses of older mothers? If not, can zygotes be screened ...
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Why doesn't recombination occur in male Drosophila?

"Males do not show meiotic recombination, facilitating genetic studies." For a while I have known that this phenomenon occurs, this quote comes from the Wikipedia page on Drosophila melanogaster, ...
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What type of cell do you start with in Meiosis?

Okay, I was learning about mitosis and meiosis in school and had a question. I know in Mitosis you first start off with a Diploid (2N) cell and then end up with two ...
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Number of spindle fibres during Metaphase?

During metaphase, the chromosomes are arranged on the equatorial plate and are attached to spindle fibres. After S phase, can the cell be said to attain the configuration of 4n? Also, during ...
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Are there verbs for “undergo mitosis” and “undergo meiosis”?

From my experience on SE sites, I believe this is the right site to ask this question under "terminology". I've been trying to find out whether English has one-word verbs for "undergo mitosis" and ...
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Is there a gene that starts meiosis 2? [closed]

Yesterday I thought about a question and asked it to my friend. The question was which gene is completely the same for a male cell that made meiosis 1 recently. My answer was the gene that starts ...
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protocol for pulldown of DNA breakpoints?

Is there any method to do pulldown enrichment of DNA breakpoints from a cell? I have found this paper reporting a method to enrich for the DNA single-strand breakpoints from meiotic recombination ...
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1answer
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What's the distinction between a tetrad and a synaptonemal complex in meiosis?

What's the distinction between a tetrad and a synaptonemal complex in meiosis? Are they synonyms? I ask because the concepts seem very closely related, but it seems like there may be a subtle ...
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What is the main general difference between Mitosis and Meiosis?

I found such a clause: The general principle is that mitosis creates somatic cells and meiosis creates germ cells. However, I cannot agree. Each gametogonium needs to go through mitosis before ...
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Does Human Female Meiosis II occur after fertilization with sperm?

I am reading the answer and I am getting confused by the sentence: At the end of meiosis I females have two daughter cells and meiosis II only occurs if and when fertilization occurs by a sperm ...
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522 views

What does entering of sex chromosomes to gametes mean during meiosis I?

I am reading one answer about meiosis: During meiosis I, the sex chromosomes separate and enter different sperm or egg cells (gametes). I assume that sex chromosomes refer here to homologous ...
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How do you see the stage of the second meiotic arrest in oogenesis in the given video?

My old question raised this new question. After reading this page I can say now that metaphase is the stage in which the second meiotic arrest occurs within oogenesis: The oocyte is arrested again ...
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At what stage of meiosis does “first meiotic arrest of oogenesis” occur?

An exam question asked what stage of meiosis corresponds with "first meiotic arrest of oogenesis". I can't work out the answer from the wiki page - can anyone explain which step this refers to?