As we have seen in the karyogram already, chromosome 1 is the largest biomolecule in human cells. It consists of 249 million base pairs. Given what you know about the dimensions of DNA, what is the actual length of chromosome 1? Please also show your calculation.
I guess if you assume the DNA is at rest with an average rise of 3.4 A per base pair, then the length of chr1 would be 3.4A * 249*10^6, i.e. 847*10^6A, i.e. ~85 mm, or 8.5 cm. Does it make sense?
This is nice information from wikipedia visit
http://en.wikipedia.org/wiki/Human_genome
and also
http://learn.genetics.utah.edu/
Molecular organization and gene content[edit]
The total length of the human genome is over 3 billion base pairs. The genome is organized into 22 paired chromosomes, the X chromosome (one in males, two in females) and, in males only, one Y chromosome, all being large linear DNA molecules contained within the cell nucleus. It also includes the mitochondrial DNA, a comparatively small circular molecule present in each mitochondrion. Basic information about these molecules and their gene content, based on a reference genome that does not represent the sequence of any specific individual, are provided in the following table. (Data source: Ensembl genome browser release 68, July 2012)
Chromosome Length (mm) Base pairs Variations Confirmed proteins Putative proteins Pseudogenes miRNA rRNA snRNA snoRNA Misc ncRNA Links Centromere position (Mbp) Cumulative (%)
1 85 249,250,621 4,401,091 2,012 31 1,130 134 66 221 145 106 EBI 125.0 7.9
I guess if you assume the DNA is at rest with an average rise of 3.4 A per base pair, then the length of chr1 would be 3.4A * 249*10^6, i.e. 847*10^6A, i.e. ~85 mm, or 8.5 cm. Does it make sense?
The actual length of chromosome 1 (well spread) in metaphase is about 10um, if the chromosome is stronger condensed it may be shortened to less than 5 um.
If chromosome 1 has length of 10 micrometer and width of 1.4 micrometer, how can 46 chromosomes fit into a nucleus with 6-10 micrometers size? (Even if we consider all coiling and physiological conditions of the cells).
I THINK IT IS JUST OK FOR METAPHASE STAGE WHEN WE HAVE MAXIMUM MANIFESTATION OF CHROMOSOMES.
if all 23 chromosomes line up at metaphase it doesn't make sense for the chromosome to be 10 mumetres; anyone have any other ideas?
metaphase chromosomes,have diffirent irange in size
from 10 μm (chromosome 1, containing 249 Mb of DNA) to
2μm (chromosome 21, containing 48 Mb of DNA).
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