Questions tagged [chromosome]

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

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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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. ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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Recombination Data Set

So I was looking over some genetics question and came across this data set. In Fruit fly Drosophila melanogaster, there is a dominant gene b+ for grey body color and another dominant gene c+ for ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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,...
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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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Number of DNA strands per chromosome

As I was reading Griffith's Introduction to genetic analysis this evidence was provided for single DNA makes single chromosome. Eventually geneticists demonstrated directly that certain chromosomes ...
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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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Barr body in mitosis

In early embryonic development, some female cells pass through a process called lionization and one of the X chromosomes get condensed and began to be called Barr body. What I don't understand is ...
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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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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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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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