BIO 229 EXAM #2 QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED GRADED A++

BIO 229 EXAM #2 QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED GRADED A++ Leave the first rating Practice questions for this set Terms in this set (78) what is a kill curve? track survival/death of a population as a function of concentration or length of exposure (more quantitaive) how can DNA be repaired from UV damage? light dependent, light independent (dark repair), SOS repair what is light-dependent DNA repair? the presence of visible light activates DNA photolyase what is light-independent (dark repair) DNA repair? enzymes cut out the damaged DNA from the double strand what is SOS DNA repair? used for significant DNA damage (longer time periods) growth versus no growth on no UV control plates - growth indicates your treatment results should be valid - negative control: untreated condition where you should expect to see growth growth versus no growth on UV treatment plates growth = bacteria could repair DNA after UV damage no growth = DNA repair mechanism absent can pigmentation protect against UV damage? yes antiseptic living tissues disinfectant inanimate surfaces chlorhexidine common antimicrobial hemocytometer % survivorship, living cell density (cells/mL) calculate living cells/mL PFUs/mL assay viability assay: looks at predation on bacteria on an agar plate trypan blue membrane exclusion dye used to distinguish live and dead (fully dark circles = dead) viable cells/mL equation PFU Plaque forming unit (remember 30-300) defined vs complex media defined: all components and amounts are known complex: not all quantities are known, supports growth of most organisms selective media selective "selects" for the growth of some organisms but inhibits the growth of others ie. Columbia CNA selects for Gram (+) bacteria differential media differential allows for "differentiation" of microbes based on their metabolic activity ie. Columbia CNA with 5% sheep's blood differentiates Gram (+) bacteria based on ability to do hemolysis Columbia CNA with 5% sheep's blood selects for ? how? selects for Gram (+) bacteria - colistin disrupts lipid outer membrane - nalidixic acid inhibits DNA gyrase (DNA replication) (excluded by Gram + thick PG layer) Columbia CNA with 5% sheep's blood differentiates for ? types? sheep blood shows differentitation of hemolysis patterns - beta: blood fully gone, clear zone indicating lysis - alpha: partially, 1 to 3mm greenish zone of incomplete hemolysis gamma: none ... look up examples Macconkey agar selects for ? how? selects for Gram (-) bacteria - bile salts disrupt exposed PG, excluded by Gram (-) outer membrane - crystal violet inhibits respiration