All Questions
Tagged with genetics chromosome
108 questions
0
votes
1
answer
66
views
Mechanism of random assortment of chromosomes
How does the random assortment of chromosomes during meiosis occur?
I am a mathematician, not a biologist, and I am surprised that it is difficult to find an answer to this question online (AI ...
0
votes
1
answer
86
views
Gene Mapping - Please explain in Lay terms
Taking an AP bio course, and for some reason I cannot comprehend the mechanism of how one determines the location of alleles on a chromosome. The math is simple and I can memorize it, but its bugging ...
0
votes
1
answer
56
views
How frequently does recombination occur, and how long are the recombinated fragments?
I understand the mechanics of recombination, but am struggling with the 'scale'.
When two homologous chromosomes pair, roughly how many recombination events occur on average? I understand there will ...
- 61
1
vote
1
answer
45
views
How to disambiguate between chromosome and chromosome pair?
Our genetic information is stored in 23 pairs of chromosomes that vary widely in size and shape. Chromosome 1 is the largest and is over three times bigger than chromosome 22.
Source: https://www.ncbi....
- 111
0
votes
1
answer
340
views
Why is There a Necessity for Two Rounds of Cell Division and Four Daughter Cells in Meiosis
Why does meiosis involve two rounds of cell division instead of stopping after meiosis I, where each daughter cell would have one chromosome randomly selected from each pair of homologous chromosomes? ...
- 139
2
votes
0
answers
190
views
If crossing over did not occur, would pairs of cells after meiosis II have the same genes?
If crossing over did not occur, would there be two pairs of cells with the same chromosomes after meiosis II? This question came to my mind while I was reading through my bio textbook. After meiosis I,...
2
votes
1
answer
513
views
Maximum number of chromosomes a human can have without dying? [closed]
I know that trisomia of chromosome 21 gives a person the Down's syndrome. Sometimes one can have sex-chromosome trisomia, and it is not apparent until adolescence. Certainly none of those problems ...
- 305
2
votes
0
answers
64
views
What is the DNA sequences between two Inverted Repeats called?
I would like to know some rules about the nomenclature of Inverted Repeats DNA sequences. More in detail, I want to know what is the name of sequences between two inverted repeats.
For example, I have ...
- 21
0
votes
1
answer
200
views
Could someone explain how chromosomes are counted here?
I'm not sure how chromosomes are counted in this picture. I would reason that there would be 8 chromosomes in the diploid cell, but that doesn't seem to be the case. Could someone explain?
- 21
1
vote
1
answer
189
views
How is it determined whether a chromosome is maternal or paternal for imprinting?
For imprinting, how does the cell determine which chromosome is maternal and which is paternal? For example, in the parental imprinting of insulin-like growth factor 2 (Igf2) on chr7 (autosome), how ...
0
votes
0
answers
299
views
Why do chromosome pairs have different shapes and sizes?
When I look at microscopic images of human chromosome pairs I see that they have different shapes and sizes.
Is there a deeper biological reason for that? Is there some evolutionary pressure for them ...
- 9
0
votes
2
answers
57
views
Chromosomal disorders
I was reading about chromosomal disorders and encountered a line stating that
'An individual may lack one of any one pair of chromosomes'
So does it mean that an individual cannot have monosomy of ...
0
votes
1
answer
180
views
What is a proximal deletion breakpoint?
I am reading a journal paper about the relationship between NCAM2 and autism. I have come across the following statement in the paper:
Based on analysis utilizing the UCSC Genome Browser (hg18, build ...
- 1,761
0
votes
1
answer
90
views
Do we come to know which allele is dominant by seeing family genration tree only?
I know that a Gene has Alleles (variation) and one is Dominant over Other i.e the Other Recessive.
Then I got a Thought that How can we tell whether an Allele is Dominant or Recessive...... and I came ...
- 109
3
votes
1
answer
287
views
Recombination Data Set
I was looking over some genetics question and came across this data set.
In the fruit fly Drosophila melanogaster there is a dominant gene b+ for grey body color and another dominant gene c+ for ...
- 59
6
votes
1
answer
149
views
Why are Chromosome Territories important?
Chromosomes occupy discrete regions of the nucleus, referred to as 'Chromosome Territories'. This spatial organization is emerging as a crucial aspect of gene regulation and genome stability in health ...
- 714
10
votes
1
answer
208
views
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 ...
- 662
1
vote
0
answers
36
views
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 ...
- 61
4
votes
1
answer
94
views
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 ...
- 819
0
votes
1
answer
200
views
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,...
- 353
0
votes
0
answers
134
views
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 ...
- 81
0
votes
1
answer
212
views
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 ...
- 103
-1
votes
1
answer
727
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).
...
- 275
3
votes
0
answers
58
views
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 ...
1
vote
1
answer
3k
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 ...
- 297
0
votes
2
answers
130
views
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 ...
- 65
0
votes
1
answer
72
views
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?
- 109
2
votes
1
answer
349
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 ...
- 23
1
vote
0
answers
36
views
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 ...
0
votes
1
answer
109
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 (...
- 103
1
vote
1
answer
2k
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 ...
- 11
2
votes
2
answers
803
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 ...
0
votes
1
answer
70
views
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?
1
vote
0
answers
173
views
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 ...
- 21
1
vote
1
answer
134
views
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?
- 1,679
3
votes
2
answers
463
views
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 ...
- 31
4
votes
3
answers
191
views
Can chromosomal crossover undo itself?
If I have alleles AB on one chromosome and ab on another, and if A and B are far from each other (and also a and b), then there is a lot of chromosomal crossovers happening. If I crossover 7 times, ...
- 151
-1
votes
2
answers
10k
views
Behaviour of chromosomes and genes
I recently read a comparison between behaviour of chromosomes and genes - which had two statements understated -
Independent pairs segregate independently of each other
One pair segregates ...
1
vote
2
answers
4k
views
Why are GC-rich regions less condensed than GC-poor regions?
As far as I know, chromatin consists of two kinds:
Heterochromatin is more condensed so translational factors have less access to this region, and this region is poor in GC.
Euchromatin is less ...
- 421
1
vote
1
answer
264
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 ...
- 113
1
vote
0
answers
70
views
How does extra chromosome 21 in Down's syndrome cause all the characteristic developmental errors? [closed]
How does the presence of an extra chromosome 21 result in the characteristic craniofacial findings, developmental errors and other health issues?
I'd like to have an exact answer, because I can't ...
- 163
2
votes
1
answer
3k
views
Why does chromosome inversion happen?
I read that chromosome inversion is a type of genetic mutation.
Why does inversion happen? What is the purpose?
I also read that if genes do not match up during cross over between inverted ...
- 229
-5
votes
1
answer
125
views
Is it possible to separate either father or mother chromosomes from a sperm? [closed]
If we were to use a flow cytometry, can it separate either the father or mother chromosomes from a sperm?
- 1
4
votes
1
answer
2k
views
How does DNA from sperm fuse with DNA in egg?
I see this statement all the time "half of our DNA (23 chromosomes) are from mom and 23 are from dad". Fine, but which chromosomes in our nucleus are from each parent? When I think of nucleus (before ...
- 295
2
votes
2
answers
2k
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 ...
- 2,979
5
votes
1
answer
27k
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 ...
- 169
2
votes
1
answer
598
views
Will a person with two copies of the same set of chromosomes be normal?
Would a (theoretical) woman (because she must have two X's), that both sets of
her chromosomes were 100% identical, be "normal"?
Would she be healthy, or would she have genetic problems as a result ...
1
vote
1
answer
441
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 46 ...
- 68.3k
2
votes
1
answer
75
views
Is a haploid essentially half of a homologous pair?
Is a haploid essentially half of a homologous pair? I understand that a haploid consists of only one set of each chromosome, so does that mean that if that chromosome was replicated the cell would ...
16
votes
5
answers
12k
views
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. ...
- 2,911