BIOL1020 Lecture Notes - Lecture 10: Borrelia, Gene Expression, Aureus
Lecture 10 - Gene regulation in bacteria !
•Bacterial diversity vastly surpasses that of archaea and eukaryotes
•Bacteria are unicellular, and some species form colonies
•Most bacterial cells are 0.5–5μm, much smaller than the 10–100 μm of many eukaryotic
cells
•Bacterial cells have a variety of shapes "
Bacteria in the environment
•parasites: in plants and animals
•Mutualistic: in our guts
•Saprophytes: essential in degradation of organic matter and nitrogen fixation
Gene expression in bacteria
•because there is no nucleus, transcription and translation happens in the same space
•A single cell has 2500-6000 genes
•The gene expression in bacteria is regulated depending on environmental and
developmental signals. This means not all genes are being expressed in bacteria at the
same time.
•For example, E Choli changes its metabolism depending on different food sources and
environment
Staphylococcus aureus!
Very antibiotic resistant and
so is a big problem in
hospitals and very common. !
Escherichia coli!
pathogenic, most
used in research!
Borrelia burgdorferi !
The cause of lime
disease.!
find more resources at oneclass.com
find more resources at oneclass.com
Operons
•bacterial genes have an operon
•An operon is a unit of genetic function. It consists of a coordinately regulated cluster of
genes with a related function
•In bacteria, genes are often clustered into operons, composed of "
– An operator, an “on-off” switch"
– A promoter"
– Genes for proteins that work together
•The genes within an operon can be switched “on” and “off” by regulatory proteins "
Example: Lac operon in E Coli
•E. coli is a bacterium that lives in the gut
•It can use lactose (milk sugar) as food "
– This requires enzymes to metabolise lactose
•The lac operon encodes genes that code for the enzymes needed to metabolism lactose
when there is no glucose.
•Lac operon encodes for 3 enzymes needed for lactose metabolism
•All the genes are:
- clustered together on the chromosome into an operon
-Controlled by single promoter
-Transcribed as a single transcript
Repressor protein: negative control !
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Very antibiotic resistant and so is a big problem in hospitals and very common. Bacteria in the environment: parasites: in plants and animals, mutualistic: in our guts, saprophytes: essential in degradation of organic matter and nitrogen xation. Gene expression in bacteria: because there is no nucleus, transcription and translation happens in the same space, a single cell has 2500-6000 genes, the gene expression in bacteria is regulated depending on environmental and developmental signals. This means not all genes are being expressed in bacteria at the same time: for example, e choli changes its metabolism depending on different food sources and environment. Operons: bacterial genes have an operon, an operon is a unit of genetic function. It consists of a coordinately regulated cluster of genes with a related function: in bacteria, genes are often clustered into operons, composed of. Genes for proteins that work together: the genes within an operon can be switched on and off by regulatory proteins.
