Questions tagged [chromosome]

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

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4answers
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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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4answers
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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? ...
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2answers
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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 ...
5
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1answer
49k views

Chromosome and chromatid numbers during cell cycle phases

A diploid cell in G1 has 6 chromosomes. How many chromosomes and how many chromatids are present in each of the following stages? Here is what I am guessing G1: 6 chromosomes ; 6 chromatids G2: 6 ...
15
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5answers
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Do men and women have the same number of genes?

As far as I know, humans have 23 pairs of chromosomes, each one which contains a particular amount of genes. But in the "last" pair, men have a XY pair chromosome, and women have a XX pair chromosome. ...
4
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1answer
17k views

What are homologous chromosomes?

I've read that homologous chromosomes are composed of one maternal chromosome and one paternal chromosome. I want to confirm if this image is for one set of homologous chromosomes: They have the ...
20
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2answers
8k 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 ...
23
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1answer
7k 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 ...
5
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3answers
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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
490 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?
4
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1answer
103 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 ...
6
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1answer
430 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 ...
4
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1answer
139 views

Polymorphism in number of chromosomes?

The answer to this question, saying that Down Syndrome - a trisomy of human chromosome 21 - is caused by de novo mutation (rather than resulting from standing variation) made me think about ...
5
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3answers
8k 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 ...
6
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1answer
1k 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 ...
3
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1answer
878 views

Why is aneuploidy usually lethal?

So, I was reading about aneuploidy and how a zygote with one extra or less chromosome usually would not survive to full term. I suppose this happens because aneuploidy leads to some kind of protein ...
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1answer
2k views

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

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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2answers
430 views

What is the difference between these two depictions of chromosome?

I understand that this is a single chromatid, but would this be considered a chromosome? Also before mitosis, the chromosomes appear as single chromatids but during interphase they replicate to form ...
6
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1answer
2k 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 ...
5
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1answer
6k 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 ...
5
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4answers
5k 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
4k views

Interpretation of picture of human chromosomes

Does this picture show sister chromatids or homologous chromosomes? If they are homologous then what is YY? If they are sister chromatids then do homologous chromosomes ever appear like this (with the ...
3
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1answer
324 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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2answers
3k views

How is the diploid chromosome number maintained at mitosis?

A normal human cell is diploid that contains 46 chromosomes in 23 pairs. Thus, when the cell undergoes mitosis, the cells still has the full chromosome with the two sister chromatids. What is it doing ...
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2answers
440 views

What are the total number of alleles for a single trait?

Humans receive a copy of gene from both parents and each gene has an alternative form called allele. Does every person possess two genes and four alleles for a single trait?
2
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1answer
92 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 ?
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2answers
541 views

Recombination frequencies

I have been learning about recombination frequencies, but an still getting a bit confused despite having gone over many of the links in Google regarding them. I was wondering if someone could verify ...
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1answer
297 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
418 views

What does min mean?

I read that "trp operon is located at 27 min on E.coli chromosome." What does "min" mean ?
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1answer
265 views

Understanding a Chromosomal formula in a karytope analysis

I am reading a medical reporting results of a karyotype analysis. On it it is written: Chromosomal formula 46,XX,del(7)(q11q36)[12]/46,XX[13] I understand that ...
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1answer
221 views

How do parents give their offspring a chromosome?

Whenever an organism sexually reproduces, it gives its offspring one chromosome from each of its pairs of chromosomes. My questions are Is this done randomly? Is it uniformly random? If so, what ...