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

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79 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
345 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
2k 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
70 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?
2
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1answer
70 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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2answers
50 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 ...
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1answer
134 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. ...
6
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1answer
48 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
46 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
62 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
76 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 ...
0
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1answer
30 views

What pattern can be learned from the data of RNA seq counts and HiC matrix? [closed]

I now have some data on the RNA seq counts and related Hi-C matrix of gene segment on a chromosome. My concern is, basically, what can we do with these data so as to establish the connection between ...
4
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1answer
35 views

Epistasis Across Chromosomes and Individuals 'Homozygous for Interactions'

Apologies for any failures in nomenclature. I'm a mathematician who is making a foray into genetics for a masters thesis. Specifically, I'm generating artificial diploid genetic sequence data and ...
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1answer
39 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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0answers
58 views

Barr body Giemsa staining

Why not all the female cheek cells show Barr Bodies when stained with Giemsa stain?? only 30 to 40 % female cells showed Barr Bodies . Why?
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1answer
115 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 ...
10
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3answers
178 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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0answers
18 views

How to engineer chromosomal duplications?

Specific genetic engineering of chromosomal aberrations like deletions, inversions and translocations are doable by using the CRISPR/Cas system or the other programmable nuclease systems. Insertions ...
1
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1answer
52 views

How was the origin of CTVT parasitic cancer determined?

The wikipedia article on CTVT says that the tumor cell has 57-64 chromosome while a normal dog has 78 chromosomes. Similarly while all chromosomes in dogs except the X and Y chromosomes are ...
4
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2answers
582 views

What effect does the Barr body have, in relation to female Turner syndrome?

Why do persons with Turner syndrome have developmental abnormalities, when normal XX-females do not, even though they only have 1 active X chromosome? From what I know, one X-chromosome is ...
4
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3answers
1k 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 ...
2
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0answers
31 views

How much difference in genome is enough to prevent interbreeding? [closed]

I am not a biologist. I am a software developer interested in genetic algorithms therefore i am probably talking to biologists who also have a knowledge of genetic algorithms. I need to "breed" ...
4
votes
1answer
103 views

Does DNA analysis allow determining amount of chromosomes?

Nowadays it is possible to sequence the DNA of extinct species, such as the Neanderthals, the Denisovans, and others. Is it possible to determine, solely from the sequenced DNA or from known bone ...
2
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1answer
227 views

What is the result of meiosis?

Is the result of meiosis ONLY the sex gametes (male and female) which later meet to form a somatic cell? Sometimes I feel as if my book is hinting towards meiosis is the process where sperm cells meet ...
0
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2answers
75 views

Chromatids in metaphase?

Please see the following picture: In my book, the author claims that these chromosomes are in metaphase (a metaphase stopped by cholchicin). I don't understand why they don't have two ...
4
votes
1answer
78 views

Definition of “structural underdominance”?

In Stathos and Fishman (2014), the authors refer to the concept of structural underdominance. The first time they mention it is in the first paragraph of the second page (left column) and the term is ...
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1answer
26 views

Which sex is homogametic in side-blotched lizards?

I'm just trying to find out whether the male side-blotched lizard is the hetero- or homogametic sex in side-blotched lizards (Uta stansburiana) - some reptiles are ZW system (female heterogamete) and ...
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2answers
52 views

Does chromosomal crossover result in a mutation?

Is chromosomal crossover considered a mutation? Would this be a large-scale mutation?
4
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4answers
134 views

Collective name for the X- and Z-chromosomes

Chromosomes are grouped as sex chromosomes or autosomes, with the X, Y, Z and W all falling in to the former category. The Z and X are present both in the homogametic and heterogametic sexes, and the ...
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0answers
37 views

Evolution of sexually concordant genetic variation on the X-chromosome

It was theorised in 1984 that sexually antagonistic genetic (SA) variation should more easily evolve on the X-chromosome. This is partly because female beneficial/male deleterious mutations face less ...
7
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1answer
70 views

Are recessive, deleterious alleles less common on the X chromosome than the autosomes in humans?

As there is a potential for them to be more readily purged in hemizygous males (and in cell lineages in females with the deleterious-allele-bearing chromosome activated), I would expect the frequency ...
4
votes
1answer
64 views

X-inactivation in ovaries

Background In all eutherian (mammals excluding the marsupials), the female (who is $XX$ for the pair of sexual chromosomes) inactivates one of her $X$. This is called dosage compensation. This ...
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1answer
1k views

Difference between Condensin and Cohesin proteins?

The chromosomal DNA is stacked with help of cohesin and condensin protein in which particular manner? Can cohesin be said to form kinetochore? How would they vary exactly? The terms are so narrowly ...
2
votes
2answers
67 views

Maintaining purebred pedigrees and how to lessen chance of getting disease?

Many breeds of dogs are known for a high incidence of genetic disorders. German shepherd and Saint Bernard dogs are predisposed to developing a crippling condition called hip dysplasia. Q: What ...
3
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1answer
440 views

How much DNA of Albert Einstein is recoverable?

Since there seem to be five biological descendants of Albert Einstein, and the original chromosomes of him distributed among them ... Is it possible to recover enough DNA of an individual from his ...
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2answers
401 views

How many recombination events are there per generation in humans?

I'm looking for a reference that tells me how many recombenation events occur in humans from one generation to the next. Assuming that the human genome is a 3.3 GigaBases long DNA sequence, how many ...
2
votes
1answer
727 views

Properties of Satellite Chromosomes

I have some questions regarding Satellite chromsomes which could not be resolved by a google search. Does the satellite consist of telomeric sequences ? If not, What is the function of a satellite ? ...
4
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3answers
9k views

Evolutionarily speaking, why do humans have 46 chromosomes

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Monkeys, chimpanzees, and Apes have 24 pairs (twenty-four pairs), for a total of 48. What caused humans to have 46? ...
2
votes
1answer
131 views

What does chromosome CHR_Un, CHR_MT in the ftp site of NCBI mean?

I am not a biologist. But need some genetic data. So I searched internet and reached NCBI's website. I came to know from the FAQ page that I can the complete genome data of organisms from ...
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0answers
34 views

examples of chromosomal aberrations with lack of sexual chromosomes?

Are there any examples in animals where individuals survive having no copies of their sexual chromosomes?
2
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1answer
47 views

How are new chromosomes replicated into the next generation via sexual reproduction?

If an individual has a new chromosome, which is very unlikely to happen, he will not have any luck in finding a sexual partner with this same trait. How will the offspring inherit this trait. And ...
3
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2answers
501 views

How was the Huntington's disease gene's location found?

I read in the book "Why we get sick." by Nesse and Williams that: Steady detective work and fabulous luck have enabled geneticists to pinpoint the Huntington's gene on the short arm of ...
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1answer
78 views

What does min mean?

I read that "trp operon is located at 27 min on E.coli chromosome." What does "min" mean ?
16
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2answers
3k views

Is there an advantage to linear chromosomes?

The DNA copying enzymes have a hard time working to the end of a chromosome. For circular chromosomes this is not a problem, since there is not a sharp 'end'. However, for a linear chromosome, without ...
4
votes
1answer
832 views

Examples of animals with different number of chromosomes that can interbreed?

When I was first started to write this question, I wanted to know how species evolve to have a different chromosomal arrangement, such as having two pairs of chromosomes instead of one? However, I ...
0
votes
2answers
48 views

about the direct intervention of a child's gender

Can we determine the gender of a child now,I mean,not randomly? There are equal amount of sperms with X chromosome and Y chromosome. Can these two kinds of sperms be distinguished easily? If yes,we ...
3
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2answers
145 views

Question about Autosomal Recessive Alleles

I had a homework question that I could not figure out. It states: A woman has cystic fibrosis in her family and did not want to have a child that suffered from the disease. She and her spouse ...
3
votes
1answer
108 views

Why is Turner syndrome rarer than Klinefelter syndrome?

Turner syndrome occurs in 1-1000 to 1-5000 females, and Klinefelter syndrome occurs in 1-500 to 1-1000 males. Why is Turner so rare even though they both are caused basically by the same mechanism?
2
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1answer
56 views

Determining whether X chromosome from sperm or egg

Is there any way of determining which X chromosome a female inherited from her father and which from her mom ?