Review:
An introduction to genetics, DNA and early human history. Aimed at general audience, made interesting with some examples of the author’s own research, makes an interesting proposition to learn more about the discussed topics.
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One of the companies offering gene analysis is 23andMe.
A genome is the whole of our genetic material. It consists of 20,000 individual genes, and a whole lot of other genetic material, the function of which is currently unknown. The genes only make up 1.5% of the genome.
That genome is then organised into 46 (23 pairs) of chromosomes. A chromosome is just a linear organisation of genes and other genetic material. The 22 pairs are the same as each other (called autosomes), and one determines sex of the person (XX – female, XY – male). In case of male the X chromosome comes from his mother and Y from his father. In case of a female, one X comes from the mother and the other one from the father’s mother. The chromosomes stay in the nucleus of the cells. But there is a miniscule bit of DNA that sits in mitochondria. It is passed only from mother to child.
The sequence of these single chemicals within the chromosome are called bases or single nucleotides. It is these chemicals within these bases which determines how that cell will function.
These single chemicals are Adenine, Thymine, Cytosine, and Guanine. This is shown as A, T, C, or G.
Each gene has a pair of bases or single nucleotides. This is because one comes from each parent. For much of the genome this pair has the same chemical base but many pairs are different. These are called single nucleotide polymorphisms (or SNPs pronounced “snips”).
Inspect the whole Science Section -->
Notes:
It has been estimated that around 107 billion modern humans lived so far. Lucy is considered to be one of the early walkers, born around 3.2 million years in Ethiopia. The oldest of ‘anatomically modern humans’ is the Omo specimen from Ethiopia, who lived around 195 thousand years ago. The oldest Neanderthal bones have been dated to around 300 thousand years ago, and none are younger than 30 thousand years ago. Homo erectus spread from Africa around 1.9 million years ago. The ‘anatomically modern humans’ spread from eastern Africa around 100 thousand years ago. The first Europeans came from central Eurasia 40 thousand years ago.One of the companies offering gene analysis is 23andMe.
A genome is the whole of our genetic material. It consists of 20,000 individual genes, and a whole lot of other genetic material, the function of which is currently unknown. The genes only make up 1.5% of the genome.
That genome is then organised into 46 (23 pairs) of chromosomes. A chromosome is just a linear organisation of genes and other genetic material. The 22 pairs are the same as each other (called autosomes), and one determines sex of the person (XX – female, XY – male). In case of male the X chromosome comes from his mother and Y from his father. In case of a female, one X comes from the mother and the other one from the father’s mother. The chromosomes stay in the nucleus of the cells. But there is a miniscule bit of DNA that sits in mitochondria. It is passed only from mother to child.
The sequence of these single chemicals within the chromosome are called bases or single nucleotides. It is these chemicals within these bases which determines how that cell will function.
These single chemicals are Adenine, Thymine, Cytosine, and Guanine. This is shown as A, T, C, or G.
Each gene has a pair of bases or single nucleotides. This is because one comes from each parent. For much of the genome this pair has the same chemical base but many pairs are different. These are called single nucleotide polymorphisms (or SNPs pronounced “snips”).
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