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Chapter

Cover Biochemistry

Genetic Information  

This chapter describes all living organisms as information-processing systems. Their ultimate source of information is encoded in the nucleotide base sequence of DNA. As biochemists have searched ever more deeply into the mysteries of genetic information storage and transmission, how DNA is replicated, and gene expression is controlled, they have transformed all of the life sciences. The chapter cites the knowledge and technologies that were acquired during this pursuit and that have provided an understanding of the intricacies of living processes that is still unfolding. It also reviews the instructions required to produce a certain type of organization that must be stably stored to safeguard their accuracy and availability for use. Information must also be converted into a form that can be utilized.

Chapter

Cover Molecular Biology

Cellular responses to DNA damage  

This chapter discusses cellular responses to DNA damage. The preservation of genetic information from one generation to the next requires the DNA sequence of the cell's genome to be maintained without alteration. Yet the integrity of the DNA sequence is under constant threat of damage as a result of errors in normal cellular processes such as DNA replication and transcription, and from reactive metabolites and environmental agents. Such DNA damage can result in changes in base sequence or even in chromosome structure. The effects of DNA damage are greatly reduced by specialized processes of DNA repair. This chapter looks at post-replication mismatch repair, repair of DNA damage by direct reversal, repair of DNA damage by base excision repair, nucleotide excision repair of bulky lesions, and translesion DNA synthesis. It also considers the DNA damage response in bacteria and in eukaryotes, and DNA damage and cell death in mammalian cells.