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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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Mechanism of random assortment of chromosomes

How does the random assortment of chromosomes during meiosis occur? I am a mathematician, not a biologist, and I am surprised that it is difficult to find an answer to this question online (AI ...
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How do we know for sure that Morus nigra (black mulberry) is tetratetracontaploidic (has 44 copies of each of its seven chromosomes)?

This answer to Is there any particular reason to choose strawberries for DNA extraction? explains that strawberries are octoploid. Wikipedia's Polyploidy and Morus nigra; Description both point out ...
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How did the fusion of Chromosome 2 spawn a separate smarter species?

I’m familiar with the evidence that two primate chromosomes fused into human Chromosome 2, and I understand that primates with such a mutation could still breed with those without it. My question is, ...
Jerry Guern's user avatar
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Gene Mapping - Please explain in Lay terms

Taking an AP bio course, and for some reason I cannot comprehend the mechanism of how one determines the location of alleles on a chromosome. The math is simple and I can memorize it, but its bugging ...
Morgan Harkins's user avatar
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Can a deletion occur on only one strand of a human chromosome?

Hello. Is it possible that a deletion can occur in the middle of only one strand of a human autosomal chromosome?
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What are the $2^{23}$ combinations in gamete fusion?

According to my textbook, when two human gametes fuse, there's $2^{23}$ different combinations of chromosomes, but I don't see how that is. The chromosomes are homologous, so they don't have any ...
user110391's user avatar
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How frequently does recombination occur, and how long are the recombinated fragments?

I understand the mechanics of recombination, but am struggling with the 'scale'. When two homologous chromosomes pair, roughly how many recombination events occur on average? I understand there will ...
user265902's user avatar
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How to disambiguate between chromosome and chromosome pair?

Our genetic information is stored in 23 pairs of chromosomes that vary widely in size and shape. Chromosome 1 is the largest and is over three times bigger than chromosome 22. Source: https://www.ncbi....
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Why is There a Necessity for Two Rounds of Cell Division and Four Daughter Cells in Meiosis

Why does meiosis involve two rounds of cell division instead of stopping after meiosis I, where each daughter cell would have one chromosome randomly selected from each pair of homologous chromosomes? ...
Growing6884's user avatar
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Are DRB3 DRB4 and DRB5 different genes or different version of the same gene

From what I understand, an individual can hold up to two HLA-DRB345 alleles (but can be less) that can each be HLA-DRB3, HLA-DRB4 or HLA-DRB5. However, since HLA-DQB1 and HLA-DQB2 are entirely ...
FluidMechanics Potential Flows's user avatar
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What makes protein binding to the DNA random?

We know that the genetic recombination process in known as a random process. On the other hand, it has also been discovered that certain proteins (such as PRDM9) determine what recombination hotspots ...
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Why are odd numbers of chromosomes (triploidy, pentaploidy) less common than even ones (tetraploidy, hexaploidy)?

Perhaps there is an obvious reason, and I know that most organisms that are either exclusively sexual or at least capable of sexual reproduction are diploid, but.... Is there a specific reason ...
Kurt Hikes's user avatar
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Total number unique chromosome combinations in fertilized egg?

Assume for this calculation no recombinations or crossover . A male gamete (sperm) is haploid and has 23 chromosomes. These gametes can be selected from the father who has 2 pairs of 23 chromosomes ...
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If crossing over did not occur, would pairs of cells after meiosis II have the same genes?

If crossing over did not occur, would there be two pairs of cells with the same chromosomes after meiosis II? This question came to my mind while I was reading through my bio textbook. After meiosis I,...
Sergiusz Strzelczyk's user avatar
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Maximum number of chromosomes a human can have without dying? [closed]

I know that trisomia of chromosome 21 gives a person the Down's syndrome. Sometimes one can have sex-chromosome trisomia, and it is not apparent until adolescence. Certainly none of those problems ...
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Human Evolution Chromosome 2: Fusion or Break?

I have a question regarding Chromosome 2. I've heard that there is evidence that the Human Chromosome 2 is a fusion between the two ancestral chromosomes 2a and 2b, but could it be possible that it ...
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The numbers of chromosomes during Meiosis [duplicate]

There is something about the numbers of chromosomes that doesn't make sense to me: Let's take this illustration: So a gamete has 23 chromosomes, which are haploid (have only one chromatid), is that ...
Ilya.K.'s user avatar
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What is the DNA sequences between two Inverted Repeats called?

I would like to know some rules about the nomenclature of Inverted Repeats DNA sequences. More in detail, I want to know what is the name of sequences between two inverted repeats. For example, I have ...
Marco Monti's user avatar
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How much is known about dinosaur DNA condensation and crosslinking?

The conclusion section of Bailleul et al. (2020) Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage is: The identification of chemical markers ...
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Do homologous chromosomes have same rates of gene expression in a cell?

I was googling around and found only articles related to XY differences in expression. Can you please clarify if homologous genes/chromosomes have about the same levels of expression in a cell or one ...
IlliakaillI's user avatar
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Could someone explain how chromosomes are counted here?

I'm not sure how chromosomes are counted in this picture. I would reason that there would be 8 chromosomes in the diploid cell, but that doesn't seem to be the case. Could someone explain?
bobfriand's user avatar
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How is it determined whether a chromosome is maternal or paternal for imprinting?

For imprinting, how does the cell determine which chromosome is maternal and which is paternal? For example, in the parental imprinting of insulin-like growth factor 2 (Igf2) on chr7 (autosome), how ...
searching for clues's user avatar
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2 answers
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Are the complementary base pairs known as genes? [closed]

In my text book ,it is written that a chromosome has 1000s of genes and it is distributed throughout the chromatids except in the centromere. But we know that the chromosomes have DNAs inside them ...
An Alien's user avatar
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Why do chromosome pairs have different shapes and sizes?

When I look at microscopic images of human chromosome pairs I see that they have different shapes and sizes. Is there a deeper biological reason for that? Is there some evolutionary pressure for them ...
zxc's user avatar
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Chromosomal disorders

I was reading about chromosomal disorders and encountered a line stating that 'An individual may lack one of any one pair of chromosomes' So does it mean that an individual cannot have monosomy of ...
Krish Chaudhari's user avatar
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Is MPseq more cost effective than FISH when looking for chromosomal abberations?

There are some papers out there that propose to use MPseq in addition to or instead of FISH when looking for chromosomal aberations in the context of cancer e.g. this one on infiltrating lobular ...
ilam engl's user avatar
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Do all stem cells have a full number of chromosomes?

Do all or only some stem cells have a full number of chromosomes?
123321123321's user avatar
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What is prochromosome?

My textbook says that prochromosome is a false chromosome present in the nucleoid of prokaryotes. I looked up Wikipedia and all over internet and this word is kinda sus. So I'm asking about it here. ...
Desai's user avatar
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How many genes per 23 chromosomes in human genome? [closed]

It is estimated that humans have between 20,000 and 25,000 genes. Every person has two copies of each gene, one inherited from each parent. There are 46 chromosomes, half from the mother, half from ...
Naj's user avatar
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How could a cell only have chromosomes from father or from mother? [closed]

How could arrangement one even be possible? How could a cell only have chromosomes from father or from mother? [Image modified from "The laws of inheritance: Figure 5," by OpenStax College, ...
HypnoticBuggyWraithVirileBevy's user avatar
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When the sister chromatids are joined in the centromere, why is it stated that the number of chromosomes is 46 and not 72?

Before the DNA is replicated in a human somatic cell, the cell has 46 chromosomes. Also, after the sister chromatids are separated during Anaphase, the chromosome number in the cell doubles to 72, so ...
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What is the structure of heterochromatin?

A short article about euchromatin and heterochromatin mentions that the structure of heterochromatin usually depicted in images "has never been visualized in vivo, and its existence is ...
David Cian's user avatar
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What is a proximal deletion breakpoint?

I am reading a journal paper about the relationship between NCAM2 and autism. I have come across the following statement in the paper: Based on analysis utilizing the UCSC Genome Browser (hg18, build ...
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Do prokaryotic chromosomes have centromeres?

I found this here. Eukaryotic chromosomes are always linear. ... In contrast, prokaryotic chromosomes are either completely devoid of centromeres or carry the so-called “plasmid centromeres” which ...
a.RR's user avatar
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Do we come to know which allele is dominant by seeing family genration tree only?

I know that a Gene has Alleles (variation) and one is Dominant over Other i.e the Other Recessive. Then I got a Thought that How can we tell whether an Allele is Dominant or Recessive...... and I came ...
Cerebral cortex 's user avatar
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2 answers
184 views

What exactly is "chromosome topology"?

I've been reading a lot about Hi-C lately, and this has been bothering me. So far as I can tell from reading around, the topology is related to the conformation of the linear chromosome. This seems ...
Chris's user avatar
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1 answer
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Recombination Data Set

I was looking over some genetics question and came across this data set. In the fruit fly Drosophila melanogaster there is a dominant gene b+ for grey body color and another dominant gene c+ for ...
Jaehyun Ahn's user avatar
2 votes
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Shrinking size of Y chromosomes

I read on the web that the size of Y chromosomes decreased in earlier period of time and the picture below tells that it is still occurring. So basically I want to know what caused this shrinking and ...
Ankit's user avatar
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2 votes
1 answer
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How can we determine which chromosome came from which parent? [closed]

In this article there is a graph (figure 1) describing different levels of methylation in the maternal and paternal chromosomes after karyogamy. How can the researchers identify which chromosome ...
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Why are Chromosome Territories important?

Chromosomes occupy discrete regions of the nucleus, referred to as 'Chromosome Territories'. This spatial organization is emerging as a crucial aspect of gene regulation and genome stability in health ...
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Why do some karyotype graphs contain 46 pairs of chromosomes?

The human genome consists of 23 pairs of chromosomes. Two copies of each pair connect to each other at the centromere. Normal karyotype graphs should look like this: But some karyotype graphs contain ...
seamos's user avatar
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3 votes
1 answer
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Does DNA being circular or linear directly affect the speed of DNA replication?

Let's say we have two DNA molecules of equal length, one belonging to a prokaryote and the other to an eukaryote. It's known that replication of the eukaryotic DNA is faster in this case. One clear ...
Ved's user avatar
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10 votes
1 answer
199 views

What causes cells to inactivate one X-chromosome?

Normally, when a cell has two X-chromosomes (female genome), one is randomly inactivated. How does the cell detect that there are two X-chromosomes in the first place? Is there some kind of protein ...
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Why do chromosomes uncoil back to chromatin after cell divisions?

At the telophase of meiotic and mitotic cell divisions, the chromosomes of daughter cells uncoil back to chromatin, but after interphase, it coils up again to form visible chromosomes. Why do this ...
Tony1300's user avatar
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chromosome 19 and recombination

Im doing a project with structural variation created by recombination within the human genome during spermatogenesis, where im especially examining intrachromatid homolog recombination. I find that ...
RAHenriksen's user avatar
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1 answer
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Chromosome size without heterochromatin

Im doing different analysis of the human chromosomes and diffent loci, however when using different databases, the heterochromatin structures are not part of the human genomes. I know that ...
Rasmus Amund Henriksen's user avatar
4 votes
1 answer
86 views

Chromosome naming convention: Why are there chromosomes named "1" and "1A"?

I've been stumbling on multiple genome of birds where there is a "1A" chromosome and a "1" chromosome. For example, the zebra finch has 1A and 4A. What does that mean? Do you have any resource about ...
M. Beausoleil's user avatar
21 votes
2 answers
4k views

Why is Chromosome 1 called Chromosome 1?

Chromosome 1 is the designation for the largest human chromosome. Humans have two copies of chromosome 1, as they do with all of the autosomes, which are the non-sex chromosomes. Chromosome 1 spans ...
fu DL's user avatar
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1 answer
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What is the Definition of Homologous Chromosomes? length, gene position are the same or similar? [duplicate]

what is the Definition of Homologous Chromosomes? this post says Homologous chromosomes are chromosome pairs (one from each parent) that are similar in length,...
fu DL's user avatar
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-4 votes
1 answer
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In a Chromosome, 2 nm is the length of what?

this figure comes from the nature 2 nm at the top right hand corner is the length of what?
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