人体共有多少细胞? @ 5/12/2016

别人的
人类基因组,又称人类基因体,是智人的基因组,由23对染色体组成,其中包括22对体染色体、1条X染色体和1条Y染色体。人类基因组含有约30亿个DNA碱基对,碱基对是以氢键相结合的两个含氮碱基,以胸腺嘧啶(T)、腺嘌呤(A)、胞嘧啶(C)和鸟嘌呤(G)四种碱基排列成碱基序列,其中A与T之间由两个氢键连接,G与C之间由三个氢键连接,碱基对的排列在DNA中也只能是A对T,G对C。其中一部分的碱基对组成了大约20000到25000个基因。
Each chromosome is made of 2 chromatids.
Each chromatid is 1 DNA molecule.
This gives 92 DNA molecules in the nucleus.

In addition -
Mitochondrial DNA (mtDNA) is present in mitochondria as a circular molecule and in most species codes for 13 or 14 proteins.
The number of mitochondria in a cell depends on the cell's function. Cells with particularly heavy energy demands, such as muscle cells, have more mitochondria than other cells. The answer is 92 + the number of mitochondria

if you consider each chromosome in a diploid cell as one big molecule, then 46 is the answer

but if you consider each of the heterocyclic amines that make up the base pairs of DNA as a separate molecule, then approximately 12 billion, since 3 billion base pairs in a haploid set of chromosomes, times two (2 amines per base pair), times two again (diploid if a somatic cell).

You will need to do additional research on your own if you also want to include the DNA molucules in the mitochondria as belonging to the body cell. Since there can be thousands of mitochondria per cell, if you count each chromosome as a "DNA molecule", and you count each much smaller DNA strand in each mitochondria as a "DNA molecule", the majority of the DNA molecules in most "normal body cells" are actually mitochondrial DNA.

There are 37.2 Trillion Cells in Your Body

How did these researchers come up with 37.2 trillion? They actually broke down the number of cells by organs and cell types, going through the literature available to come up with a detailed list of volumes and densities in everything from intestines to knees. So, for example, there are 50 billion fat cells in the average body, and 2 billion heart muscle cells. Adding all those up, they got 37.2 million. (This doesn’t include any of the millions of microbes living on you, by the way.)
发布于 5/12/2016 23:35:58 | 评论:0

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