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During conception, after unwinding, one of the two DNA strands from both the male and female conjoin and rewind. Has anyone looked at what happens to the other 2 DNA strands?

Hi William,

Not sure where you got that information from, which is a bit off.

This is what happens after fertilization: a zygote with both maternal and paternal set of DNA in the form of 23 times 2 chromosomes.
With this union, the sperm which had 23 and and the egg which had 23 chromosomes, result in the 46 chromosomes of the zygote. The haploid set of chr in the gametes is restored to 46 which should be maintained in all somatic cells (that is, excluding the gametic cells of the individual) throughout the life of the person, the zygote is going to evolve into.

So, how does this zygote ensure the 46 count?
The two strands in each chromosome are from the same parent (mother or father) and not one from each. Each of these two strand serves as a template for making a new strand before the cell divides. They do this by unwinding, serving as a template and then the rewind with the newly synthesized template. Not the original one.

I think you confused the two homologous chromosomes with the strands in each chromosome. Homologous chromosomes are the matching chromosomes from each parent. Eg. Chr 1 from mother, Chr 1 from father and so one upto the chr. 22. In a female, One X is from mother and one from father. In a male, the X is always from mother and the Y has to be from father.




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Thanemozhi Natarajan


Answers in Genetics, genomics, cytogenetics of syndromes, congenital anomalies, cancer, clinical genomics and interpretation of omics data.


More than 10 years. Doctoral research thesis on Congenital anomalies and cytogenetics, Recurrent reproductive failure and chromosomal abnormalities. Postdoctoral experience in Breast cancer research. Current: Clinical Genomics and Pharmacogenomics.


Cancer Cell International, Cancer Epidemiology Biomarkers and Prevention, Breast cancer research and treatment, Indian Journal of Pediatrics, BMC Proceedings, Pharmacogenetics and Genomics, Human Molecular Genetics, Frontiers in Genetics, Cancer Biomarkers.

PhD Biomedical Genetics

Awards and Honors
University Grants Commission Award for pursuing PhD level research (India); Travel awards to attend conferences.

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Post doctoral experience Cancer research, molecular epidemiology Current: Clininical Genomics and Pharmacogenomics

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