Questions tagged [chromosome]
A single piece of DNA coiled and organized along with RNA and proteins found in the cell.
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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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For the same person, is it true that DNA nucleotide sequences are nearly identical on homologous chromosomes?
We know that any two randomly chosen human individuals differ only in 1 nucleotide pair per every 1000 nucleotide pairs. This figure fits well with the finding that only 0.1% of the human genome ...
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How do chromosome count differences produce viable offspring during speciation in animals with sexual reproduction
So, many closely related animals have different chromosome counts.
It would seem that most chromosome count differences lead to sterile offspring. Further, it would appear that gametes with ...
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Why/ how sister chromatids stay together after replication?
As we know, in mitosis, after S phase each linear DNA molecule (associated with 1 chromatid), get doubled. These sister chromatids, in prophase and metaphase; are joined with a common centromeric ...
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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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how many crossing over sections are in human dna?
i have found in wikipedia:
At a given chiasma, an exchange of genetic material can occur between
both chromatids, what is called a chromosomal crossover, ...
In humans, there seems to be one ...
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Is it possible to assemble chromosomes from different parent cells?
Assuming that one or two parents are carrying a genetic defect/disease which is localised on a specific chromosome, would it be possible to assemble a new haploid cells taking a (half) chromosome from ...
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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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Identify which of the two columns A and B represent gene and chromosome
I am a bit confused on this question in my Textbook (STD 12) and have got all sorts of answers on searching it but I am still not able to comprehend it literally.
Can someone answer this and explain ...
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Are human cells tetraploid during cell division?
If human cells are diploid, and DNA replicates before cell division, does it mean that our cells are tetrapolid for a short period of time (DNA replication - cell division). Photos of chromosomes are ...
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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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1answer
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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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1answer
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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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1answer
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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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2answers
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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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1answer
95 views
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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1answer
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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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1answer
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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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1answer
789 views
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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2answers
692 views
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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2answers
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What is the chance a given gene will end up in a given gamete?
Let us say a germ cell had a desired allele. This germ cell was replicated during interphase so that it had two of the desired allele. It then underwent meiosis.
My question then is, what is the ...
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1answer
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Are there chromosomes that we inherit that are not recombinated? [closed]
We do have chromosomes that recombinated ,but aren't there pure chromosomes that are not recombinated that people would have?
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Is there any system how genes are spread across chromosomes?
Every chromosome being a wrapped DNA molecule contains thousands or more genes.
Now, is there any system why a gene A goes to a chromosome K and gene B to chromosome J?
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With over 400 chromosomes, does mitosis in a species of butterfly happen in the same way as in humans?
The beginning of the Ars Technica article Gene editing crunches an organism’s genome into single, giant DNA molecule begins:
Complex organisms have complex genomes. While bacteria and archaea keep ...
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1answer
113 views
How do the chromosomes arrange themselves after fertilization in humans?
In human reproduction the male produces sperm containing 23 chromosomes and the female has the oovum containing 23 chromosomes , so after fertilization the zygote contains 46 chromosomes. What I want ...
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Did the chromosomal fusion within humans affect phenotypical change compared to the separated chromosomes in the other apes?
I just read this article on the evolutionary divergence between humans and chimps, and how the most significant event was when the 24 number of chromosomes in chimps was reduced to 23 in humans due to ...
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1answer
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Human genome, chromosomes
I have a very basic question, but it seems the hardest to me.
So we have 46 chromosomes (23, 2 copies of each). Do all chromosomes have the same DNA? If so, does it mean that in different cells with ...
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1answer
85 views
What exactly happens during the crossover [closed]
My knowledge of biology is rather limited, but I think I have a grasp of some basic concepts. For me (as a person close to math) a chromosome is a sequence of elements from the set {A,C,T,G} of some (...
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1answer
631 views
Genotypes of gametes produced by an F1 individual?
I have an urgent question as I have an exam tomorrow. I was skimming some past exam papers and one question came up which has me completely confused.
A cross was made between a pure breeding diploid ...
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2answers
329 views
Why the genome is divided into several chromosomes and not just a single big chromosome?
In many eukaryote species, there are several chromosomes. In humans, for example, there are 23 pairs of chromosomes.
Why are there several chromosomes and not just a join of all chromosomes into a ...
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1answer
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On what basis is each chromosome given a number? [duplicate]
On what basis is each chromosome given a number? There appears to me to be no visible ordering between each pair. Is there any reason other than differentiation?
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1answer
41 views
How does the number of chromosomes evolve through generations? [duplicate]
Mitosis is a complex mechanism that, through mutations and crossover, determines how a chromosome is composed. But at that point, the number of chromosomes is already determined: how can this number ...
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What is(are) the mechanism(s) that stop cells from fusing in vivo?
I just learned about the phenomenon of 'cell fusion' in which two diploid somatic cells can combine into some aneuploid cell in vitro and proceed to proliferate in culture. Apparently this can even ...
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Coefficient of relatedness for a locus on the Z chromosome
So i know that the ZW determination system is the equivalent for XY in birds. Moreover, I know that the coefficient of relatedness between siblings for the X chromosome is 0.5 so im guessing that the ...
0
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1answer
164 views
Are the sister chromatids exactly the same?
I'm having doubts about whether the sister chromatids are exactly the same or not. I know that they are the arms that carry the information genes (the alleles), but I don't know if they are exactly ...
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1answer
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V(D)J recombination on homologous chromosome
V(D)J recombination is known to recombine IG locus of a B cell. Is anything known about how the recombinations on two homologous chromosomes are connected? For example, are the selected V(D)J couples(...
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1answer
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What is linkage?
If two genes are on the same chromosome, are they always “linked”? What if they are more than 50 cM apart? Then they would follow Mendalian pattern of inheritence. So are they still linked?
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Human ancestor reproduction after chromosome fusion
I read somewhere that human chromosome 2 is the result of 2 primate chromosomes fusing together somewhere along our evolutionary journey. This is why we have 23 chromosomes while other primates have ...
