MICR 221 Lecture : MICR 221 - Transposons%2C plasmids and conjugation.docx

• School: Queen's University
• Department: Microbiology and Immunology
• Course: MICR 221
• Professor: N/ A

Document Summary

Each gene encodes a single protein or can also code for rna: structural (pili, flagella, cell wall, transport/export, signal transduction, enzymes: catabolic and degradative, rna e. g. trna, rrna. Genome determines the nature and activities of the cell (phenotype i. e. observable properties) Phenotype is not constant because not all genes are being transcribed at the same time: ex planktonic v/s biolfilm state. Genome is not constant; additional sources of dna (dna is not constant: plasmids, gene transfer from other bacteria. Extrachromosomal dna molecules (physically separate from the chromosome) Carry genes, usually not essential genes (if cell loses plasmid it can still grow) Self replicating (copy themselves independently from the chromosome: own origin of replication independent of chromosome. Much smaller than chromosome (3-10 kb v/s 2-4 mb for bacterial chromosome) Characteristic copy number- often correlates with actual size of plasmid low copy 1-2 per cell (large plasmids usually: high copy number (30->100, smaller plasmids)