Column 1
The time required for a cell to undergo binary fission is called
Generation Time
Viruses that attack bacteria are known as
Bacteriophages
Bacteria stain as gram positive or gram negative because of structural differences in the?
Cell Wall
What is regulon and what is an operon?
Regulon: A set of operons controlled by the same regulatory proteins is a regulon.
Operon: A cluster of genes (often in procaryotic cells) whose expression is controlled by a single operator is operon.
The difference between chemoorganotrophy and chemolithotrophy is ________.
chemoorganotrophs use organic compounds as an energy source while chemolithotrophs use oxidation of inorganic chemicals for the generation of energy.
What does the term ‘herd immunity’ mean?
A high enough proportion of the individuals in a population are immune to a pathogen
What are the three method of horizontal gene transfer?
Conjugation - DNA is transferred from a donor to a recipient bacterium by direct contact.
Transduction -a bacterial virus (bacteriophage) transfers DNA from one cell to another.
Transformation- genetic transfer process by which free DNA is incorporated into a recipient cell and brings about genetic change.
What are the three steps and temperatures of PCR
Denaturation - 95
Annealing - 56
Extending - 72
Differentiate between sterilization and disinfection
Elimination of microorganisms of all types from an environment by physical or chemical means is called sterilization, while destroying, removing or inactivating pathogenic microorganisms from an environment is referred to as disinfection.
What are the phases of a bacterial growth curve?
Log phase
Lag phase
Stationary Phase
Death Phase
•Lag phase:
–A lag is also observed when a microbial culture is transferred from a nutrient-rich culture medium to one that is nutrient-poor.
–In order to grow, cells must have a complete complement of enzymes for synthesis of the essential metabolites not present in that medium.
•Exponential phase:
–Exponential phase cells are typically in their healthiest state.
–Exponential growth rates are influenced by the growth conditions an organism is experiencing as well as genetic characteristics of the organism itself, e.g., prokaryotic cells grow faster than eukaryotes.
•Stationary phase:
–In the stationary phase, there is no net increase or decrease in cell number and thus the growth rate of the population is zero.
–Despite growth arrest, energy metabolism and biosynthetic processes in stationary phase cells may continue, but typically at a greatly reduced rate.
•Death phase:
–Typically, however, the rate of cell death is much slower than the rate of exponential growth and viable cells may remain in a culture for months or even years.
What is potable water
Water which undergoes extensive treatment that includes both filtration and chlorination and is suitable for human consumption is called potable water.
What is another term for Biosynthesis? What is its opposite?
Give examples for both.
Anabolism, Catabolism
Respiration, Photosynthesis
Give the steps involved in viral reproduction.
The steps involved are: (1) Attachment or absorption, (2) penetration or injection, (3) early steps in replication, (4) replication, (5) synthesis of proteins used as structural subunits of capsid or the viral coat, (6) assembly or packaging, and (7) release of the mature virus particles from the host cell.
You inoculate a culture with exactly 100 bacterial cells. After 3 hours, there are 6400 cells of bacteria present. What is its generation time?
k = [(log 6400) - (log 100)] / (log 2)
=[(log 6400) - (log 100)] / 0.301
= (3.81 - 2) / 0.301
= 6 generations
t = 60 min x 3 hours t = 180 min
generation time = 180 min / 6 generations generation time = 30 min
A phage stock is 100 times serially diluted 4 times. 0.1 mL of the fourth dilution is plated on a lawn of susceptible bacterial cells. After incubating overnight, 180 plaques are counted. What is the titre of the phage stock(pfu/mL) ?
Dilution factor =100^4=10^8
Number of plaques counted = 180
titre of the phage stock(pfu/mL)= 1.8 x 10 ^11