An organized structure of DNA and proteins found in the cell.
25
votes
3answers
879 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. ...
11
votes
1answer
396 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 ...
9
votes
1answer
471 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 ...
9
votes
1answer
143 views
Do single crossovers occur in circular polynucleotides?
Single crossovers in circular pieces of DNA do not seem to be a big topic, because if they happened, they would lead to a kind of combined chromosome with two inner strands and one large outer strand. ...
6
votes
4answers
160 views
Chromosomes are of different size but why do all chromosomes have similar GC percentage?
When I browsed NCBI I saw a pattern: even if the chromosome sizes, number of genes, and number of proteins are different, GC% in chromosomes tend to be similar. The examples are linked below.
Yeast,
...
6
votes
2answers
209 views
Finding the number of chromosomes of an organism
For a school project I need to find the number of chromosomes of an organism (specifically the adelie penguin, Pygoscelis adeliae). After several internet searches and a look through the encyclopedia ...
6
votes
1answer
230 views
Does every mitochondrion in a cell contain the same DNA?
I know that mitochondria of eukaryotes have their own DNA, more similar to that of bacteria than to the rest of the cell's DNA. I also know that a cell can have plenty of mitochondria, and I ...
5
votes
1answer
92 views
Why was polyploidy not lethal in certain octodontid rodents?
As discussed in Why is polyploidy lethal for some organisms while for others is not?, polyploidy is normally lethal in mammals.
However, two species of Octodontidae (South American rodents), are ...
5
votes
1answer
68 views
Number of spindle fibres during Metaphase?
During metaphase, the chromosomes are arranged on the equatorial plate and are attached to spindle fibres. After S phase, can the cell be said to attain the configuration of 4n?
Also, during ...
4
votes
1answer
138 views
What phenotypes can arise from gender-related aneuploidy?
Humans normally have 46 chromosomes (two copies - one from each parent - of each of the 24 chromosomes: [1:22] + [XX or XY]).
Aneuploidy is an abnormal number of chromosomes - Down's syndromes is an ...
4
votes
1answer
46 views
What value type would a chromosome position be in a database or form?
I wanted to create a tool for some fields like SIFT, Phenotype, etc..so for example I know Phenotype will have "Text" values or SIFT will have some determined values from a drop down list...but what ...
3
votes
2answers
124 views
Is it possible to correctly identify presence of Y chromosome with external physical test only?
I asked a question related to the third sex, and I came to know that its always possible to categorize a human to male or female with presence of Y chromosome.
Now, I have another question. Is there ...
3
votes
1answer
141 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 ...
3
votes
1answer
69 views
How does a tiger have stripes?
A vague question, but let me try to explain. My friend explained to me that in females, some cells use one X chromosome, while all others use the other X chromosome. This can result in some ...
2
votes
2answers
84 views
Is it more likely that the very first living organisms had a linear genome?
Is it right to assume that the first living organisms on earth had a linear genome? I base this on the fact that linear macromolecules are clearly much more common in nature that circular ones. To be ...
2
votes
1answer
198 views
What is the structure and function of chromosomes during interphase?
Ok, it seems to be easy but I have probably ignored something by accident.
Interphase is the phase where things are growing and the preparation for cell division happens. Its stages G1, S and G2. DNA ...
2
votes
1answer
36 views
What's the difference between a free chromosome fragment and an extrachromosomal array?
This is reference to a review on C. elegans mosaic analysis by Yochem and Herman, in which the authors make a distinction between free chromosome fragments and extrachromosomal arrays.
For the ...
2
votes
2answers
77 views
Can a new Y-chromosome be created?
The major gene of the Y-chromosome is SRY. Would it be possible to get the X-chromosome and add SRY to create a "fuller" Y-chromosome?
What advantage does the skinny Y-chromosome give an individual ...
2
votes
1answer
47 views
How can chromatin state be measured?
I have some RNA-Seq data and I'd like to align it to the physical genome and see which sections of chromatin are geometrically open and being transcribed. The data are already sequence-aligned, and ...
2
votes
1answer
73 views
Have there been any experiments that duplicate chromosome copies from 23*2 to 23*3 or 23*4?
Deinococcus radiodurans is an amazing bacterium with a fantastic survival rate. It can survive to high doses of radiation, in a complete vacuum and in hydrochloric acid.
How does this bacterium ...
2
votes
0answers
28 views
Example(s) of reduced rate of mitotic progression?
Most species complete mitosis, and in particular the process of chromosome condensation, rather quickly, in a matter of minutes. Are there any known species that undergo mitoses with substantially ...
1
vote
3answers
1k views
Evolutionally 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?
...
1
vote
1answer
42 views
Can IVF decrease the probability of trisomy in the fetuses of older mothers?
Is trisomy mostly due to complications with fertilization?
If so, does in vitro fertilization reduce the probability of trisomy for the fetuses of older mothers?
If not, can zygotes be screened ...
1
vote
1answer
51 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. ...
1
vote
0answers
31 views
Are there any mammals in which polyspermy produces viable zygotes?
Are there any mammals in which polyspermy produces viable zygotes? In the wikipedia page it is mentioned that there is a delicate equilibrium between female defenses against many sperms, which ...
0
votes
1answer
81 views
What is the advantage of circular genomes for bacteria and linear genomes for other organisms?
Bacterial are a great group of organisms. They have circular genomes and never went toward linear genomes while other organisms show the opposite strategy and don't have circular genomes (disregarding ...
0
votes
1answer
60 views
Would two species of yeast with similar genome sizes have the same number of genes or chromosomes?
Similar organisms generally have similar genome sizes. Given this, would two species of yeast have the same number of genes and chromosomes?
Edit: Fixed with thanks to @daniel-standage
0
votes
0answers
101 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 ...
