When we say the human genome has 3 billion base pairs, does that mean each cell has 3 billion base pairs in total within its 23 chromosomes?

Explanation:

The complete human genome is comprised of nuclear DNA and mitochondrial DNA.

The "3 billion base pairs" is the length of total haploid DNA in a single cell, and includes the sum of both sources of DNA: the set of 23 chromosomes + one set of mitochondrial DNA.

I'm attaching a Table that shows the length in bp of every chromosome and the mitochondrial DNA (mtDNA), where you can see that the sum of the length in bp of each chromosme adds up to the 3 billion base pairs.

The Table is extracted from the publication: Piovesan, Allison et al. “On the length, weight and GC content of the human genome.” BMC research notes vol. 12,1 106. 27 Feb. 2019

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4. lower carbon footprint