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3

Genomes: Molecular Maps of Living

Organisms

Abstract

Based on sequence comparisons, special algorithms assemble the sequence fragments

of modern sequencing techniques. After bacterial genomes and the yeast cell genome

were completely sequenced and bioinformatically analysed in the 1990s, human

genomes and numerous other eukaryotic (cells with a cell nucleus) genomes followed

from 2001. The function of individual genes is identified by sequence comparisons:

Protein function analysis (see Chap. 1), but also annotation of regulatory genome ele­

ments (ENCODE consortium) are main tasks of genome analysis. The genome sequence

is available for almost all known organisms. It is thus possible to successfully predict

the essential molecular components of these organisms.

3.1

Sequencing Genomes: Spelling Genomes

In the previous chapter we dealt with RNA as a “magic” molecule. But what about the

permanent storage of information in the cell, the totality of DNA, the genome?

DNA means deoxyribonucleic acid, abbreviated to DNA in English, and is an excellent

storage medium for information that living organisms have been using for almost 3 billion

years. As is the case with our modern storage media, the read-in and read-out technology

is quite important, because mostly only transcripts are produced, via RNA (see previous

chapter). If, on the other hand, a unicellular organism reproduces or a multicellular organ­

ism grows, the cells of the body divide. And before they split into two halves, the genetic

information in the cells has to be duplicated. There is an enzyme for this, the polymerase,

and with it, adenine, guanine, cytosine and thymidine pair up as a new DNA strand to the

opposite strand. With many nucleotides per second, an exact copy is thus produced. This

process was first used by Frederick Sanger to read genetic information. He marked the

© Springer-Verlag GmbH Germany, part of Springer Nature 2023

T. Dandekar, M. Kunz, Bioinformatics,

https://doi.org/10.1007/978-3-662-65036-3_3