Flashcards in bacterial growth and microbial genetics Deck (57)
what is a pure culture
population of organisms descended from a single cell and is therefore separated from all other species
what did Robert Koch develop?
solid media (agar-agar derived from seaweed)
Contained in dishes invented by Kochs lab assistant Julius Richard Petri
What is Binary fission?
after a bacterial cell has increased in size and doubled all of its parts, it divides
Define microbial growth
an increase in the number of cells in a population
Define generation time
time it takes for a population to double in number
Bacterial growth in a lab (a closed system) follows a pattern of stages called _______
What are the 4 stages of the growth curve?
Lag phase (latent)
Exponential phase (log)
Describe the lag phase (latent)
Cells "ramp up" by synthesizing macromolecules required for division & ATP
Describe the exponential phase (log)
cells dividing at a constant rate, growth is balanced with available nutrients
Describe the stationary phase
cells have exhausted supply of energy and nutrients, number of cells remains relatively constant
Describe the death phase
population decreases as cells die off at a constant rate
What are the 2 methods to measure growth?
- direct count method using microscope and hemacytometer
- indirect cell counting using serial dilution
Adenine pairs with?
Guanine pairs with?
A set of 3 nucleotides on a single strand =
a codon - this encodes a specific AA
Where does DNA replication begin?
replication origin (ori)
Is DNA replication semi-conservative?
What direction does DNA replication proceed in?
5' to 3'
Whats the difference between the leading strand & the lagging strand?
Leading strand= continuously synthesized
Lagging strand= discontinous, synthesized in pieces
What are the pieces of the lagging strand called?
Describe the central dogma
DNA --> (transcription) --> RNA --> (translation) --> protein
mRNA is synthesized from DNA via RNA polymerase
RNA nucleotides are adenine, uracil, guanine, cytosine
new mRNA is moved to ribosomes for translation
process of synthesizing proteins
occurs on ribosome
AAs are assembled into growing polypeptide chain (when folded= protein)
During transcription what acts as an on/off switch?
A regulatory region near the promotor which a regulatory protein can bind to
What is an operon?
a set of adjacent genes coordinately controlled by a regulatory protein and transcribed as a single RNA message
Is an operon inducible, repressible or both?
Genes that are not always being transcribe must be ______ to function
Genes that are always being transcribed must be ______ to prevent proteins from being made
An inducible operon requires what?
an inducer to prevent a repressor protein from binding to the operator