*Protection of bacterial Chromosome.
-Methylation: CH3 added to adenine and cytosines on bacteria chromosome as last DNA replication step.
- Advantages: 1.)Allows mismatch repair system to identify old vs. new (i.e. "Right" vs "wrong") DNA strands
2.)Allows identification of potential viral DNA.
*Restriction Enzymes: Enzymes that recognize/bind to particular sequences of DNA bases in DNA strand and beak DNA strand there. Example: 5' ATCCCGCA 3'
- Bacteria make lots of different restriction enzymes that bind to/break DNA at lots of different sequences.
*defense against viral infection
*Viral DNA not methylated.
**New hand out **
DNA > Instructions (like a blue print) —>DNA copies to RNA (called transcription)> Protein—> Building blocks of organism.
Gene=DNA instructions for a particular protein.
*Transcription: Initiation: Determining which bit of DNA will be copied to RNA
-Promoter Sequence: Where transcription occurs- where DNA is unwound and unzipped so RNA copy can be made. -Promoter sequence have lots of T and A. (TATA box- TATAAT- like sequence at almost all promoter sites.
- Promoter Sequence: While having common TATA- box sequence,. also have variability in surrounds bases.
*RNA polymerase: Enzyme that copies DNA into RNA copy. (RNA copy is single-stranded, complementary to oneDNA strand.
RNA Polymerase binds to promoter sequences on DNA - Sigma Factor : Subunit of RNA polymerase that binds to DNA promoter sequences. Different sigma factors attach to different promoter sequences - Different sigma factors expressed under different conditions.
