Microbiology Notes Sept 14

Bacterial Genetic Structures

- Nucleoid
** this is not a nucleus- instead it is bunched up bacterial DNA
A. Chromosomes
- the cells DNA
** unlike cells of humans and other eukaryotic cells BACTERIAL CELLS HAVE CIRCULAR STRUCTURE
-bacteria keep DNA wound up in tight bunches when they are not actively using them
-almost all have just one chromosome per bacterium
- b/c of this 1 chromosome bacteria do not have dominant or recessive genes
Question: If Bacteria have DNA in a circular for how does it uncoil them when needed?

B. DNA gyrase - a molecule/ enzyme uncoils the bunches of DNA when needed by the cell such as when bacteria needs to
copy its DNA

Bacterial Cells need to watch out for: CIPROFLOXACIN!

ciprofloxacin destroys the activity fo DNA gyrase so the bacteria is not able unwind its DNA to transcribe it

C. Plasmids
- small cirlces of DNA that contain just a few genes "accessory genes"
- plasmids are easily shared among bacteria

The reason that people exposed to anthrax on Sept 11 were treated with ciprofloxacin:

- not only did people not want to trust the terrorist advice to treat with penicillin we know:
- some of the strains of anthrax that existed had been gentically engineered to be resistant to penicillin
- this resistance was achieved by putting plasmas with penicillin - resistance genes into the bacteria

D. Ribosomes

- synthesize proteins
- all living things have ribosomes
-ribosomes synthesize protiens by translating mRNA into and amino acid sequence

Amanda Schwingler.

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