Transcript Microbial Genetics

If post is spelled P-OS-T and most is
spelled M-O-S-T, how
do you spell the word
for what you put in the
toaster?
Microbial Genetics
General Biology
SUNY Orange at S. S. Seward
Institute
It's At The 20! The 10! Can
The Flu Go All The Way?
by Laura Lorson
Tobacco Mosaic Disease
Red Neck Bird Dogs
Bacterial and viral growth curves
Lytic cycle of phage T4
Viral structure
Phage Infecting Bacteria
• Sorenson animation
• T4 Assembly
Viral reproductive cycle
Adenovirus
Reproductive cycle of an enveloped virus
HIV infection
Couple at AIDS quilt
HIV, a retrovirus
Smallpox
Measles
Polio
Hepatitis
Influenza epidemic
Influenza Virus
• video
Herpes
Emerging viruses
Deer Mouse – vector for hantavirus
Viral infection of plants
Tobacco mosaic virus
Prion Diseases
Kuru
Creutzfeldt-Jakob Disease
A hypothesis to explain how prions propagate
Replication of the bacterial chromosome
E. coli
E. coli dividing
Bacterium releasing DNA with plasmids
Plasmids
Genetic recombination produces
new bacterial strains:
Transformation
Transduction
Conjugation
Transformation
• The alteration of a bacterial cell’s
genotype by the uptake of naked,
foreign DNA from the surrounding
environment
Detecting genetic recombination in bacteria
Transduction
• Occurs when a phage carries bacterial
genes from one host cell to another
• Generalized transduction – a small
piece of the host’s cell degraded DNA
is packaged within a capsid
• Specialized transduction – occurs
when extra DNA is taken when
prophage genome is excised
Transduction
Transduction
Transduction
Transduction
Conjugation
• Transfers genetic material between 2
bacterial cells temporarily joined
• F factor – about 25 genes, most
required for production of sex pili
– Either in chromosome or on plasmid
– Episome – any genetic material that
undergoes reversible incorporation into a
cell’s chromosome
• Ex. F plasmid, any temperate phage
Bacterial mating
Conjugation and recombination in E. coli
Conjugation and recombination in E. coli
Conjugation and recombination in E. coli
Conjugation and recombination in E. coli
R Plasmid
• R for resistance
• Also have genes for sex pili
• Therefore can be transferred from one
cell to another by conjugation
Transposons
• Pieces of DNA that can move from one
location to another in a cell’s genome
• A type of recombination
– Chromosome to plasmid
– Plasmid to chromosome
– Plasmid to plasmid
– Chromosome to chromosome (Jumping
gene)
Barbara McClintock, Ph.D., Nobel
Prize laureate
Insertion Sequence
• Consists of DNA necessary for the act
of transposition
• Requires a transposase gene
• Flanked by a pair of inverted repeat
sequences
Insertion sequences, the simplest transposons
Insertion of a transposon and creation of direct repeats
Composite transposon
• Extra genes sandwiched between two
insertion sequences
Anatomy of a composite transposon
The control of gene expression
enables individual bacteria to
adjust their metabolism to
environmental change.
Regulation of a metabolic pathway
Regulation of a metabolic pathway
Operon
-a unit of genetic function (bacteria and
phages) regulated clusters of genes
with related functions
1. gene(s) that it controls
2. Promoter region where RNA
polymerase first binds
3. Operator – between promoter and the
first gene – acts as on/off switch
The trp operon: regulated synthesis of repressible enzymes
The trp operon: regulated synthesis of repressible enzymes
The lac operon: regulated synthesis of
inducible enzymes
The lac operon: regulated synthesis of
inducible enzymes
cAMP (Cyclic Adenosine Monophosphate)
Positive control: cAMP receptor protein
Positive control: cAMP receptor protein