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Questions tagged [chromosome]

A single piece of DNA coiled and organized along with RNA and proteins found in the cell.

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Offspring of parents with different number of chromosomes

Many papers report that dog-whelks (Nucella lapillus) show a distinct chromosomal polymorphism between populations of 2n = 24 up to 2n = 36. Could somebody please tell me how many chromosomes the F1 ...
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Do we know which traits reside in which chromosome? If not, how about the next 10 years? [closed]

Assuming we develop a technology that allows us to make human gametes (sperm & eggs) combining chromosomes from different persons. Thus we take 1st chromosome from 1st person, 2nd chromosome from ...
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Is there any evidence of homologous somatic pairing in taxa aside from Dipterans and budding yeasts?

Homologous somatic pairing is the physical colocation and pairing of the paternal and maternal chromosomes in a cell during growth phases of a cell. This is interesting as most taxa that we know about ...
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How much shorter is the short arm of a chromosome? And why?

I keep reading that the p arm is shorter than the q arm. But I cannot find an explanation of how much shorter nor an explanation for the difference.
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What is an “end-to-end fusion” in the context of telomerase? [closed]

Telomerase is said to prevent "end-to-end fusion" of chromosomes. My question is threefold: What is an "end-to-end fusion"? How does Telomerase prevent end-to-end fusions? Why do end-to-end ...
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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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What is a chromosome?

I read the wikipedia article and am confused if a chromosome is the pair of two chromotoids or if each chromatoid is considered a chromosome. I've heard someone say we have 23 pairs of chromosomes ...
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What is the chance a given gene will end up in a given gamete?

Let us say a somatic cell had a desired gene. This somatic cell was replicated during interphase so that it had two of the desired gene. It then underwent meiosis. My question then is, what is the ...
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Are there chromosomes that we inherit that are not recombinated? [closed]

We do have chromosomes that recombinated ,but aren't there pure chromosomes that are not recombinated that people would have?
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Is there any system how genes are spread across chromosomes?

Every chromosome being a wrapped DNA molecule contains thousands or more genes. Now, is there any system why a gene A goes to a chromosome K and gene B to chromosome J?
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1answer
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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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How do the chromosomes arrange themselves after fertilization in humans?

In human reproduction the male produces sperm containing 23 chromosomes and the female has the oovum containing 23 chromosomes , so after fertilization the zygote contains 46 chromosomes. What I want ...
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Did the chromosomal fusion within humans affect phenotypical change compared to the separated chromosomes in the other apes?

I just read this article on the evolutionary divergence between humans and chimps, and how the most significant event was when the 24 number of chromosomes in chimps was reduced to 23 in humans due to ...
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Human genome, chromosomes

I have a very basic question, but it seems the hardest to me. So we have 46 chromosomes (23, 2 copies of each). Do all chromosomes have the same DNA? If so, does it mean that in different cells with ...
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1answer
60 views

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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Genotypes of gametes produced by an F1 individual?

I have an urgent question as I have an exam tomorrow. I was skimming some past exam papers and one question came up which has me completely confused. A cross was made between a pure breeding ...
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2answers
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Why the genome is divided into several chromosomes and not just a single big chromosome?

In many eukaryote species, there are several chromosomes. In humans, for example, there are 23 pairs of chromosomes. Why are there several chromosomes and not just a join of all chromosomes into a ...
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1answer
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On what basis is each chromosome given a number? [duplicate]

On what basis is each chromosome given a number? There appears to me to be no visible ordering between each pair. Is there any reason other than differentiation?
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How does the number of chromosomes evolve through generations? [duplicate]

Mitosis is a complex mechanism that, through mutations and crossover, determines how a chromosome is composed. But at that point, the number of chromosomes is already determined: how can this number ...
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What is(are) the mechanism(s) that stop cells from fusing in vivo?

I just learned about the phenomenon of 'cell fusion' in which two diploid somatic cells can combine into some aneuploid cell in vitro and proceed to proliferate in culture. Apparently this can even ...
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Coefficient of relatedness for a locus on the Z chromosome

So i know that the ZW determination system is the equivalent for XY in birds. Moreover, I know that the coefficient of relatedness between siblings for the X chromosome is 0.5 so im guessing that the ...
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1answer
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Are the sister chromatids exactly the same?

I'm having doubts about whether the sister chromatids are exactly the same or not. I know that they are the arms that carry the information genes (the alleles), but I don't know if they are exactly ...
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1answer
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V(D)J recombination on homologous chromosome

V(D)J recombination is known to recombine IG locus of a B cell. Is anything known about how the recombinations on two homologous chromosomes are connected? For example, are the selected V(D)J couples(...
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What is linkage?

If two genes are on the same chromosome, are they always “linked”? What if they are more than 50 cM apart? Then they would follow Mendalian pattern of inheritence. So are they still linked?
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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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2answers
342 views

Do chromosomes change with time?

An offspring is 23 chromosomes of mother and 23 of father, if one of the mate learns say music after the birth of their first child— will their second offspring have better music skills than former? ...
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Why can plants handle extra chromosomes much better than animals? [duplicate]

Why can plants handle being polyploid way better than animals, where it is almost always fatal? I found a 2004 paper while searching about this topic, but I'm wondering if there have been any recent ...
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Why may some telomeres not appear on metaphase chromosomes using Q-FISH?

There are some chromosomes that appear to have missing telomeres e.g. 2 instead of the expected 4, but there appears to be no fusions or breaks.
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What is the X-chromosome responsible for? [closed]

I understand that the X-chromosome is responsible for certain disorders, like red-green colorblindness; but besides disorders, what do the genes on the X-chromosome determine?
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What are the total number of alleles for a single trait?

Humans receive a copy of gene from both parents and each gene has an alternative form called allele. Does every person possess two genes and four alleles for a single trait?
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Does incomplete dominance follow or not follow the law of segregation?

The law of segregation says that in hetrozygotes, dominant and recessive alleles remain together without mixing into one another. In incomplete dominance, two alleles blend with each other, and the ...
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1answer
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what is the difference between gene and allele? [closed]

I want to know about gene and allele As we know allele is pair of genes they are ;present on only one chromosome or on homologous chromosomes? Or its like that;one chromosome has only one gene out of ...
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Does Meiosis I produce haploid gametes?

According to my textbook (and other online sources), Meiosis I produces two haploid cells. After Meiosis (does not note if after Meiosis II), haploid gametes are produced. Does this information mean ...
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Are there examples of cells with more than one nucleus?

I've always wondered why cells have only one nucleus, as having multiple would seemingly prevent mutation. Are there examples of organisms with multiple nucleuses? If not, is there a reason?
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Don't understand how multiple replication bubbles work

I'm not exactly sure how multiple replication bubbles work, assuming were working with a linear, eukaryotic chromosome. This is a diagram for reference: It appears that the DNA is being synthesized "...
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1answer
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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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Genetics… Translocation

Can a Translocation of chromosomal parts occur between an autosome and an allosome? If it occurs in between allosomes,what could be the effect of Robertsonian Translocation between an X and a Y ...
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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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How come our thyroid glands don't suffer awful mutations (or do they)?

I was listening to a lecture by my Biology professor and he said that the thyroid gland contains radioactive Iodine which can break down and create reactive Oxygen species (because ionizing radiation ...
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Can chromosomal crossover undo itself?

If I have alleles AB on one chromosome and ab on another, and if A and B are far from each other (and also a and b), then there is a lot of chromosomal crossovers happening. If I crossover 7 times, ...
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Behaviour of chromosomes and genes

I recently read a comparison between behaviour of chromosomes and genes - which had two statements understated - Independent pairs segregate independently of each other One pair segregates ...
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Evolution and different number of chromosoms? (a non-biologist)

I understand that a species becomes a different one slowly and in a continuous way. However, the different number of chromosomes is bugging me. Chimpanzees, for example, have 48 chromosomes whereas ...
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1answer
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Why are GC-rich regions less condensed than GC-poor regions?

As far as I know, chromatin consists of two kinds: Heterochromatin is more condensed so translational factors have less access to this region, and this region is poor in GC. Euchromatin is less ...
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1answer
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How do parents give their offspring a chromosome?

Whenever an organism sexually reproduces, it gives its offspring one chromosome from each of its pairs of chromosomes. My questions are Is this done randomly? Is it uniformly random? If so, what ...
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1answer
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Does aneuploidy include the loss of chromosome arms?

I'm wondering if the definition of aneuploidy includes loss of a chromosome arm (telosomy) or arms (ditelosomy). I'm aware that aneuploidy normally depends on the number of discrete chromosomes (so a ...
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How does extra chromosome 21 in Down's syndrome cause all the characteristic developmental errors? [closed]

How does the presence of an extra chromosome 21 result in the characteristic craniofacial findings, developmental errors and other health issues? I'd like to have an exact answer, because I can't ...
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1answer
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Why does chromosome inversion happen?

I read that chromosome inversion is a type of genetic mutation. Why does inversion happen? What is the purpose? I also read that if genes do not match up during cross over between inverted ...
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1answer
79 views

By what mechanism can two chromosomes fuse?

What condition(s) would likely exist which could cause 2 chromosomes in the newly fertilized egg of a placental mammal to fuse? Assume this is more likely than having the same chromosome pair fuse in ...
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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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Stability of the chromosomes of thermophilic bacteria

We know thermophiles — generally archaebacteria — can survive high temperature, but their genomic DNA also contains hydrogen-bonded nitrogen bases. Why don't they collapse like ordinary hydrogen bonds?...