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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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How did the molecular machinery for recombination originate?

I'm wondering about the origins of genetic recombination. During crossover new chromosomes are created. They have different allele combinations from the original two chromosomes. This process allows ...
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Is it possible for a sex chromosome to be homologous?

I am following a great introductory biology course online, MITx: 7.00x on edX. A question in the course assumes a cross between a pure-breeding male fly and a pure-breeding female fly: You are ...
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The organisms of the same species with a different number of chromosomes [closed]

I am looking for some specific creatures. The organisms of the same species that have different chromosome numbers. Just like male grasshopper (23 chromosomes) and female grasshopper (24 chromosomes). ...
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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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Is there a practical upper limit to ploidy?

In my AP Biology class, we were discussing polyploidy, specifically, its deleterious nature in mammals and its prevalence in plants. We also learned that commercial crops, especially fruit, are often ...
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Why more than one chromosome in an organism?

Why not one chromosome to house genome in organisms but multiple? Is it for epigenomic purposes?
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Factors affecting which chromosome will come from the father

Tell me please. In course of biology, I remember that a man has XY chromosomes, and a woman has only X. Accordingly, depending on which chromosome comes from Father(man) Y or X, a girl (XX) or a boy (...
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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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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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283 views

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
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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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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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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
429 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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2answers
121 views

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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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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293 views

Is a microspore diploid?

In gymnosperms the plant body is predominantly sporophytic. It produces microspores or megaspores my textbook says that these undergo reduction division in order to form male gametophytes pollen ...
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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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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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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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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 ...