Unit 1: 1.5 Structure of the Genome Higher Biology Unit 1: 1.5 Structure of the Genome

Learning Intentions To be able to describe the structure of the genome To be able to explain the functions of the different parts of the genome

Success Criteria I can describe the structure of the genome I can explain the importance of the coding and non coding regions I can explain the purpose of the coding and non coding regions

Genome The genome of an organism is the genetic information stored in its DNA The human genome is about 3 billion base pairs of DNA long The genome is made up of coding and non coding regions Only 2% of the genome is coding

Non coding regions The non coding regions of the genome often take the form of DNA sequences that are repeated thousands of times over The functions of many of these sequences remain unknown but some play important roles that are understood

Regulation of transcription RNA polymerase is unable to initiate the transcription process on its own. It needs transcription factors. Some are activators (help start transcription) and some are repressors (prevent transcription).

Activators are bound to sequences of DNA called regulator sequences Activators are bound to sequences of DNA called regulator sequences. Often these can be at some distance from the coding sequence.

The DNA must bend to bring the regulator and the activators bound to it in contact with other transcription factors close to the promoter.

Protection Some of the non coding regions form a protective structure known as a telomere at each end of a chromosome The telomere prevents damage to the chromosome by fraying at its ends

Non translated RNA Some of the non coding regions of the genome form RNA molecules other than mRNA tRNA and rRNA are both transcribed form non coding regions but are not translated

Success Criteria I can describe the structure of the genome I can explain the importance of the coding and non coding regions I can explain the purpose of the coding and non coding regions