Читать книгу Cell Biology - Stephen R. Bolsover - Страница 60

The set of 23 chromosomes that we inherit from each parent encodes a complete copy of our nuclear genome that resides in the nucleus of our cells. We have a second genome that resides in our mitochondria – the energy‐producing organelles inside our cells. Unlike our large nuclear genome, which is organized in linear chromosomes, our mitochondrial genome is circular and only 16 569 base pairs in length. The mitochondrial genome contains 37 genes but only 13 of these encode proteins. These proteins are all involved in mitochondrial energy production. While nuclear genomes are inherited from both parents, our mitochondrial genome is always inherited maternally. This has allowed a prediction of “mitochondrial Eve,” the most recent female ancestor from whom all living humans descend in the matrilineal line, estimated to have lived between 165 000 and 190 000 years ago.

Figure 3.1. Adenine nucleotides. (a) Deoxyadenosine triphosphate. The H on the 2′ carbon of the ribose ring is circled. (b) Adenosine triphosphate. The OH group on the 2′ carbon of the ribose ring is circled.

Figure 3.2. The four bases found in DNA.

Figure 3.3. The phosphodiester bond and the sugar‐phosphate backbone of DNA.