The Basic Genetics of Reproduction Posted: 01-18-06 12:02pm
Why do sex cells only have 23
chromosomes?
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DoctorAnswer
Doctor Answer
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General Q&A Answer A212 Posted: 01-26-06 15:41pm
Humans have somatic cells and sex cells.
Somatic cells (all cells in the organism
except for sex-cells) are diploid (have 46
chromosomes) and sex cells (spermatozoids
and egg-cells/ovum) are haploid (have 23
chromosomes). Sex cells create a new
organism when one spermatozoid joins with
one egg-cell. The newborn cell (zygote)
consists of 46 chromosomes (23 chromosomes
from each sex-cell) and a whole organism
develops from it. So, sex-cells contain 23
chromosomes because if they had 46
chromosomes the newborn cell(zygote) would
have 92 chromosomes(46+46), which is
not-normal (tetraploid). Finally, sharing
chromosomes from both a mother and a
father ensures the originality of the
offspring, which is a combination of the
two.
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