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

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What's the difference between “mixing” and “combination” of chromosomes? [on hold]

What's the difference between "mixing of chromosomes" and "combination of chromosomes" ?
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1answer
71 views

What exactly are genes, DNA and chromosomes. How do they relate to each other and what is their function? [on hold]

So I am new to biology and I have been reading, and searching the web, but I couldn't understand the whole framework of a cell. So as I understood: A DNA, is a double chain of Nucleotides (A,T,G,C ...
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1answer
55 views

Maintenance of Diploid chromosome number at mitosis

I'm just not understanding this: A regular human cell is diploid - because it has 46 chromosomes, in 23 pairs. So that means that when the cell undergoes mitosis, it will still have the full ...
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1answer
40 views

Why does meiotic recombination disrupt the independent assortment of genes on the same chromosome?

There are many sources that say that genes that are "linked" by being on the same chromosome assort with each other -- that when an allele is passed on that the gamete containing said allele will also ...
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1answer
58 views

4DGenome or another comprehensive database of chromatin interactions

I'm searching for the most comprehensive source of chromatin interactions to support enhancer targets (data such like Hi-C, ChIA-PET, IM-PET, 5C, 4C, 3C, etc.) and my question according that could be ...
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4answers
134 views

The human has 46 double chromosomes or simple chromosomes?

What I mean: does the human cell have 46 of these: or 46 of these: Thank you in advance.
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2answers
41 views

From 46 human chromosomes, is each one from a single parent?

Humans have 23 pairs of chromosomes. Each chromosome in pair is homologous to another one in pair. Does this imply, that the entire chromosome in any cell is obtained from only one parent? I mean ...
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1answer
29 views

Does common X-like picture represent one doubled chromosome or two homologous chromosomes?

What is on common X-like picture of chromosome? Here is the image from Wikipedia: Are (for example) lower petals homologous to each other? If yes, then why (1) ...
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1answer
117 views

Clarification on the “orientation” of chromosomal rearrangements

I need some clarifications on the concept of "orientation" in case of chromosomal rearrangements. Given a deletion event on a chromosome for example, is the resulting DNA at the breakpoint always in ...
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1answer
38 views

What are the significances of chromosome mapping? [closed]

The few point that I have come across are: The following are the significances of chromosome mapping: Chromosome maps help identify the location of gene of interest on a chromosome for genetic ...
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0answers
44 views

How do chromosome pairs get “paired up” for protein synthesis?

If my understanding is correct, during interphase a normal human cell will have 46 chromosomes scattered about in the cell nucleus. These chromosomes can be thought of as pairs: there are two copies ...
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2answers
47 views

What is the length of the centromeric repeat sequence in a human?

I'm looking for the lengths of the centromeres of human chromosomes. The best I could come up with so far has been: The length of individual centromeric arrays was found to range from an average of ...
4
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1answer
40 views

Is complete linkage found in all four chromosomes or only Y-chromosome of Drosophila? [duplicate]

Male Drosophila shows complete linkage. Is it observed for all four chromosomes or only the Y chromosome?
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1answer
155 views

Why are mice with a single X chromosome and no Y chromosome males?

I was searching online and I read this article Mice can be male without Y chromosome and this is a part of it: The experiments demonstrate that there are multiple ways to make males, says Richard ...
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0answers
19 views

Why is down syndrome more common than other trisomies? [duplicate]

Why is Down syndrome more common than say trisomy 18? Is chromosome 21 easier to replicate? Or is it because those babies are more viable?
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3answers
64 views

Whole Genome Sequencing and B Chromosomes

Do whole genome sequencing techniques detect B chromosomes if such chromosomes are present? My understanding is as follows: How the DNA material in a B Chromosome is mapped depends on the reference ...
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1answer
896 views

How are 23 chromosomes in human sperm chosen?

I'm not biologist and I have just a basic knowledge. I've been thinking for a long time about the following question: How does the body choose which 23 chromosomes should be active in human sperm and ...
3
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0answers
20 views

What would the resulting karyotype be if someone with Klinefelter syndrome fertilized an “empty” egg?

Endoreduplication: is a form of nuclear polyploidization that results in multiple, uniform copies of chromosomes. This process is common in plants and animals, especially in tissues with high ...
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0answers
35 views

Why are published chromosome counts for polyploids often incorrect by an integer multiplication factor of the original diploid like count?

Why are published chromosome counts (done using techniques such as root smashes) for polyploidy flowering plants often incorrect by a multiplication factor of 2 or 3 from the original diploid like ...
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1answer
142 views

Why do humans have 46 chromosomes? [duplicate]

Humans have approximately 25000 genes. Why are these genes on 46 chromosomes? Why not 40 or 50?
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1answer
1k views

recombination frequency problem

Three loci C, D and E are located on the same chromosome in this order. We found that the frequency of recombinants between C and D is 10% and that between D and E it is 20%. Assuming that ...
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1answer
213 views

Why does size decrease across the sequence of human chromosomes?

The following graph shows a decrease in the amount of base pairs per chromosome across the sequential set of human chromosomes: Is this because chromosomes were originally numbered by their size on ...
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0answers
15 views

Are both chromosomes transcribed and translated? [duplicate]

Or is it somehow regulated if both or only one chromosome is transcribed/translated?
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1answer
80 views

When does a chromatid become a chromosome?

When chromosomes lie on the metaphase plate, they have the characteristic X shape. But these are actually two chromatids that are held together at the centromere. If separation fails and both ...
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0answers
105 views

What is the relation between chromomere & nucleosome?

I've been lately studying structure of chromosome where I got these two terms. I got many definitions of them. Nucleosome: The basic structural sub-unit of chromatin, consisting of $\sim 200$ base ...
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1answer
199 views

Which of the two chromosomes in a pair is expressed?

I have completely dummy question. I have 23 pairs of chromosomes in the cells 23 single coming from my mother and 23 single from my father. So how my cell choose which chromosome, mother's or father'...
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0answers
24 views

Mitotic chromosome condensation screen

If I want to screen for mutant yeast (S. cerevisiae) colonies that have defects in mitotic chromosome condensation, can I screen for colonies arrested in Mid-M phase? Would that work?
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1answer
34 views

Transcription when Chromosomes are Condensed

Are genes transcribed just as well when chromosomes are condensed? I want to design a screen that depends on genes not transcribed when chromosomes are condensed (to identify cells that can't ...
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3answers
2k views

Chromosome 2 fusion?

I read this article by Jeffrey Tomkins and Jerry Bergman claiming to debunk chromosome 2 fusion. Is there anything wrong with these conclusions? " 1.The reputed fusion site is located in a peri-...
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1answer
126 views

What is a holocentric chromosome?

I was doing this question that asked: "How many centromeres does a typical chromosome have?" I thought one and the answer was:"One, except for holocentric chromosomes." So then what are "...
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3answers
92 views

Whole Genome Sequencing and Chromosome Counts

In general, do standard whole genome sequencing techniques rely more on known chromosome counts, independently arrive at chromosome counts, and/or not directly address issues such as base number, ...
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0answers
83 views

How do we know Denisovans had 46 Chromosomes

What allows sequencers to conclude that Denisovans had 46 chromosomes rather than merely knowing Denisovans had the crossover material arranged in 48 or say 44 chromosomes? See http://genetics....
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4answers
5k views

Why is polyploidy lethal for some organisms while for others is not?

Polyploidy is the multiplication of number of chromosomal sets from 2n to 3n (triploidy), 4n (tetraploidy) and so on. It is quite common in plants, for example many crops like wheat or Brassica forms. ...
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0answers
55 views

Differing Flow Cytometry Genome Sizes and Sexual Mating Implies Differing Chromosome Counts

Do the fundamental principles of genetics strongly suggest the following is a derived conjecture? If 2 flowering plant species A and B have widely differing genome size (at a minimum a 50% difference)...
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4answers
282 views

How does the molecular machinery choose where to cut a chromosome for recombination?

I'm wondering about a few technicalities of crossover in meiosis. The point of crossover is to create new chromosomes that don't have the same allele combinations as the original two chromosomes. ...
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1answer
159 views

Explanation about cytogenetic notation

What is the correct meaning of cytogenetic notation "inv(4)(p13q22)" ? Inversions at chromosome 4, at the p arm 13 is inverted AND at q arm 22 is inverted OR Inversions at chromosome 4, the ...
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1answer
60 views

Are genes uniformly dispersed throughout the genome?

I think that telomeres and centromeres are regions with a very low gene content (= regions that contain few genes). To the exception of telomeres and centromeres, are genes uniformly distributed ...
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1answer
82 views

How does chromosome fusion get fixed in the population?

It's well known that one of human chromosomes is the result of fusion between two chromosomes in a primate ancestor. If we put anthropocentrism aside, it becomes clear that fusion events happened a ...
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2answers
80 views

Referencing the homologous chromosomes

There exist a co-ordinate system from chromosomes like "12p11.3". In this system, first integer range from 1 to 23 i.e it takes homologous chromosomes as a pair. If we want to distinguish among ...
7
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1answer
343 views

What determines the number of chromosomes an organism carries?

This is an extension of this question about What limits chromosomal length?. I am wondering what could be the specific reasons behind the number of chromosomes an organism carries. In other words, ...
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1answer
685 views

What does it mean to “map the human genome”

I know some elementary chemistry and biology. I also think I know what a gene is (it's a sequence of DNA which encodes a particular protein). I also know that on a chromosome there are sections of DNA ...
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1answer
3k views

Are human chromosomes connected or separate molecules?

Do the 46 human chromosomes form a single unbroken DNA helix? Or is it rather that a human's genome consists of 46 disconnected helices? If it is the former, does the common numbering scheme for ...
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3answers
1k views

Is the size of the genome across species roughly the same?

Chromosome number differs across species. Is the amount of DNA comparable between organisms, just being split into smaller chunks in those species with more chromosomes? Or do species have different ...
11
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1answer
146 views

What limits chromosomal length?

What are the upper and lower limits for chromosome length? Are these limits different in different species or kingdoms? If there is any limit, which cellular or molecular factors are reasons?
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1answer
122 views

From a computer science perspective, how is DNA compared for various purposes?

I am very interested in privacy preserving technolgies, such as Microsoft PINQ and would like to see if this is applicable to DNA comparison. Given that I don't have a background in biology, I ...
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1answer
153 views

Interlocus Contest Evolution means suicide?

I was reading Matt Ridley's "Genome" book. I am trying to understand the Interlocus Contest Evolution in his X-Y chapter. I do not understand why the X and Y chromosome would want to kill each other. ...
7
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1answer
144 views

Chromosome picture, how to interpret?

In this guide i was reading for annotations, there is a diagram of chromosomes of D.mel, I am confused as to why the chromosomes are all attached to one another, is this picture taken in a certain ...
3
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1answer
58 views

Why do genes with closely related functions often reside on different chromosomes?

Why do genes with closely related products are so often positioned on different chromosomes? To illustrate what I mean, here is an example from immunology: the invariant region of MHC is on ...
6
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2answers
91 views

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 ...
6
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1answer
322 views

Why is it harder to sequence plant genomes than animal genomes?

Plants seem to be less complex organisms than animals, but despite that there are less plant genomes sequenced. Is that because plant genomes are more complex, for example in terms of regulatory ...