Binary fission: bacterial
populations grow exponentially
Is bacterial growth constant?
Bacterial population growth phases: lag, log, stationary and death
A small amount of bacteria is added to media and the number of cells in the
culture is determined at
What genes would you identify using a
blood agar plate screen? (can use gene
products in place of gene names).
Mutations in what gene might allow
increased virulence by allowing secretion
of multiple toxins? What kind of mutation
Using your knowledge of chemotaxis regulatory mechanisms,
indicate how a repellent might work:
Draw a simple diagram, starting with a receptor for the repellent,
and including CheA, and CheY, regulatory proteins, and the
flagellar motor. Indicate how the
Traits are based on
content of the
genome, and passed
Replication is bidirectional and semi-conservative
Initiation of DNA replication is dependent on the concentration
of ATP-bound Dna
Bacteria are able to adapt to different environmental conditions.
There can be rapid responses or evolution to specialized growth.
What are 3 distinct modifications (acting on different types of cell structures)
that may be necessary for a bacterial cell
What genes could you identify using a chemotaxis mutant
Flagellin is the major
protein component - used
to make the filament.
How many genes could you identify?
What types of mutations would be present?
Using genetics to
Genetic analysis overview
Look for mutants
Identify genes (from mutants)
Genes that are altered in mutants isolated
What do all cells need
to grow and
Where do they get it?
Cells require 1) a source of
carbon (and other
elements) and 2) energy, in
order to synthesize the
components necessary for
Different microbes use
different nutrient sources:
Questions on structure of the course?
15-20 In-class assignments
8-12 short quizzes
Can you identify each of these?
What are their component parts?
What holds them together?
How are these related to each other?
Bacterial structure and growth
Model of a bacterial cell (Escherichia coli)
Think about how various microbial structures promote growth
The envelope: cell membrane, cell wall, appendages
What is the function of the cell me
EM micrograph of Gram+ and Gram(-) bacterial
Wash step is able to
remove Crystal violet
stain from Gram(-) cells.
Why do you need the
Safranin counter stain?.
Snooki and Paris Hilton are
The Cell Wall
The bacterial cell wall consists of a single interlinked molecule usually peptidoglycan - creating a mesh that surrounds the
cell outside the membrane.
2. Compare the permeability of peptidoglycan to a lipid
What are the characteris
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Whats a microbe?
Do you recognize this? What makes it a microbe?
How many different types of microbes do you know?
How many different types of microbes