Class Notes Chapter 18

Qualities of a Virus:

• protein coat called a capsid and has receptors


• non-living (lives off host), parasitic


• Retrovirus (RNA), example: HIV


• Replicate by lysogenic or lytic cycle


• Encloses viral genome (RNA or DNA)


• Tail fibers


• Bacteriaphage

Qualities of Bacteria:

• Prokaryotic


• Binary Fission


• Shapes: coccus, coccobacillus, sprillium, bacillius (these determine whta kind of bacteria they are)


• only 1% are harmful


• DNA processes: Transformation, Transduction, and Conjugation


• 2 Domains: Archebacteria and Bacteria


• 1 Kingdom = Monera


• unicellular organism


• Prophage


• Nutrition Modes

Notes From Class:

• MRSA is a bacteria that can't be fought with antibiotics

LAC OPERON:

• inducable


• turn off


• allolactose helps to turn it back on, inducer

• Allolactose (sugar), is an isomer of lactose, depresses the operon by inactivating the repressor. In this way the emzymes for lactose utilization are induced.


• Tryptophan is an amino acid produced by an anabolic pathway catalyzed by repressible enzymes.


• The trp operon is turned on; a RNA polymerase can bind to the promoter and transcribe the genes of the operon. The operon can be switched off by a protein called the trp repressor.


• RNA polymerase attaches to the DNA at the promoter and transcribes the operon's genes.


• As tryptophan accumulates, it inhibits its own production by activating the repressor protein, which binds to the operator, blocking transcription.


• Protein ---> sequence determines the function