MGY277 Unit 5 Exam
Study Guide
Calculate number of cells after a certain number of doublings - Answer Nt = No x 2^n
where Nt = number o cells at a given time (minutes) No = the initial number of cells
Chemostat - Answer keeps number of cells in media constant; drips fresh media into the
chamber and equivalent vol5ume of culture is removed as new cells are added; allows
for uniform conditions; speeds the growth
Closed culturing system - Answer nutrients are not removed; wastes are not removed;
batch cultures yield characteristic growth curve
Open Culturing systems - Answer required to maintain continuous growth; continuous
culture; nutrients added and wastes removed continuously
Cryo-preservatives - Answer prevents cells from dying when media is frozen by
preventing ice crystal formation (stops water from expanding); like glycerol or dimethyl
sulfoxide
Phases of growth in a closed culture system - Answer Stages: Lag, Log, Stationary,
Death
Lag stage - Answer stage: number of cells do not increase; begin synthesizing enzymes
required for growth, delay depends on conditions
Log stage - Answer stage: doubling time of growth (measure generation time); creates
lipids, AAs, and nucleotides; most vulnerable to antibiotics
Secondary metabolite - Answer creates toxins to prevent other cells from growing
Stationary stage - Answer stage: no dividing, low level of metabolism
Death stage - Answer stage: cells die and become food for other bacteria; media
becomes depleted and full of waste product
Biofilm - Answer bacterial and fungal organized communities stuck onto a surface with
flagella and pilli; causes slimy surfaces; resistant to antibiotics; grows slower and have
water channels unlike planktonic cells made of proteins, DNA, extracellular gel
Psychrophile - Answer prokaryote that optimally grow in really cold arctic regions
(-15°-15°C); no human pathogens
Psychrotroph - Answer prokaryote that optimally grow in 20°-30°C; involved in food
spoilage
Study Guide
Calculate number of cells after a certain number of doublings - Answer Nt = No x 2^n
where Nt = number o cells at a given time (minutes) No = the initial number of cells
Chemostat - Answer keeps number of cells in media constant; drips fresh media into the
chamber and equivalent vol5ume of culture is removed as new cells are added; allows
for uniform conditions; speeds the growth
Closed culturing system - Answer nutrients are not removed; wastes are not removed;
batch cultures yield characteristic growth curve
Open Culturing systems - Answer required to maintain continuous growth; continuous
culture; nutrients added and wastes removed continuously
Cryo-preservatives - Answer prevents cells from dying when media is frozen by
preventing ice crystal formation (stops water from expanding); like glycerol or dimethyl
sulfoxide
Phases of growth in a closed culture system - Answer Stages: Lag, Log, Stationary,
Death
Lag stage - Answer stage: number of cells do not increase; begin synthesizing enzymes
required for growth, delay depends on conditions
Log stage - Answer stage: doubling time of growth (measure generation time); creates
lipids, AAs, and nucleotides; most vulnerable to antibiotics
Secondary metabolite - Answer creates toxins to prevent other cells from growing
Stationary stage - Answer stage: no dividing, low level of metabolism
Death stage - Answer stage: cells die and become food for other bacteria; media
becomes depleted and full of waste product
Biofilm - Answer bacterial and fungal organized communities stuck onto a surface with
flagella and pilli; causes slimy surfaces; resistant to antibiotics; grows slower and have
water channels unlike planktonic cells made of proteins, DNA, extracellular gel
Psychrophile - Answer prokaryote that optimally grow in really cold arctic regions
(-15°-15°C); no human pathogens
Psychrotroph - Answer prokaryote that optimally grow in 20°-30°C; involved in food
spoilage
