Cell Growth and Product Formation Flashcards
Growth Curve and 4 Phases
True Lag vs Apparent Lag
Definitions
During Apparent Lag, part of the population grows from time 0 at it’s maximum rate, another portion fails to grow.
During True Lag the lag in the growth involves the entire population
True Lag vs Apparent Lag
Causes
Apparent: May be caused by death of some organisms or by a selecive medium ( mutant or genetic variants)
True Change in Nutrition, Physicial Env, Inhibitor, State of Inoculum culture (cells in stationary phase)
How to minimize Lag Phase
Only true phase
Take inoculum from late exponential growth phase.
Conditions of the new growth medium should be close to that which the inoculum was taken.
Use larger inoculum size.
Be able to determine specific growth rate and population doubling time (PDT) in the exponential growth phase.
Know the relative population times for different types of organisms
bacteria, yeast, insect cells, mammalian cells.
no f way you need to know this
Bacteria: 20 - 30min
Yeast: 1 - 1.5h
Insect Cells: 15 - 24h
Mammalian Cells: 20 to 24h
Stationary and Decline Phases
characteristics and causes (stationary)
Stationary
Net Growth = 0 , Non-growing cells lose enzyme activity
Causes: Nutrient Exhaustion, Growth inhibition, Maximum packing density of cells or contact inhibition.
Decline
Characterized by autolysis and decrease in biomass.
Some mammalian cell cultures have essentially no stationary grow
Primary and secondaty metabolites
differences
Prymary: Essential for life and replication of cells.
Primary metabolism functions similarly in most organisms.
Secondary: Non-essential for cell growth. Formation is dependant on envirionmental conditions. Second Metabolite is formed in only a few organisms. Regulation of biosynthesis varies significantly from that of primary
Fermentation
Strict and less restrictive definition.
Strict: An aerobic process used for producing products
Less Restrict: Use of microbial cultures for producing chemical, or pharma products.
