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BACTERIA & VIRUSES
A. UNIVERSAL COMMON ANCESTOR
• 1. First living cells
• a. anaerobic
• b. heterotrophic
• c. bacteria
• 2. ancestor of all other living things
• 3. U.C.A.
B. TRAITS ALL ORGANISMS GOT FROM UCA
• 1. DNA = universal genetic material
•
a. same nucleotides
•
b. double helix
• 2. DNA replication to reproduce
•
a. semi conservative
•
b. helicase
•
c. DNA polymerase
•
d. topoisomerase
C. DOMAINS
• 1) Domain Bacteria
•
Eubacteria
• 2) Domain Archaea
•
Archaeobacteria
• 3) Domain Eukarya
•
Eukarya
D. BACTERIA ANCESTRAL TRAITS
• 1) no histones
• 2) single circular main chromosome
E. BACTERIA
CELLULAR
STRUCTURES
• 1. Nucleoid – main chromosome
• 2. Plasmid – small circular DNA trading cards
• 3. Ribosomes –only organelle
• 4. Pili – projections of cell membrane
• 5. Capsule – gelatinous coating
• 6. Flagella – with NO microtubules/ basal body
BACTERIAL REPLICATION
http://www.youtube.com/watch?v=7sZ5
Nz8_cfc
F. BACTERIAL REPLICATION
• 1. Origin duplicated
• 2. DNA helicase unwinds DNA
• 3. DNA polymerase complex called replisome
• 4. 2 replication forks move opposite directions
• Topoisomerase cuts DNA to avoid over-coiling
G. PROKARYOTIC FISSION
• 1. Origins attach
• 2. Cell elongates
• 3. Cytoplasmic
division
• 4. No random
assortment
H. GENETIC VARIATION IN BACTERIA
• 1. Lateral genetic exchange
• 2. Advantage = rapid dissemination new
phenotypes
•
a.) conjugation – bacteria to bacteria via
tube
•
b.) transduction – virus introduces new DNA
•
c.) transformation – uptake of DNA through
cell membrane (plasmids)
• Famous transformation experiment by…
•
Griffith
CONJUGATION
• http://highered.mcgrawhill.com/sites/dl/free/0072835125/126997/animation6.ht
ml
I. BACTERIAL CONJUGATION
• 1. Donor cell (F+) gives a plasmid to
recipient cell
• 2. F+ fertility plasmid directs sex pilus
formation
• 3. Conjugation tube joins cytoplasm
• 4. Relaxase nicks donor plasmid
• 5. One strand of plasmid nucleotides
moves into recipient cell
• 6. Both strands replicated back into double
helix
J. BACTERIAL MUTATION RATES
• 1. Very high due to rapid reproduction rates
• 2. chance of any gene mutating each time
it is replicated……
•
1 in 10 million
• 3. If 2 x 1010 new cells produced each day
•
2000 will have new mutations
K. IDENTIFYING/CLASSIFYING BACTERIA
• 1. Characteristics that are considered
• a) Shape
• b) Gram staining
• c) Metabolism
• d) Gene sequencing….
•
i. causing re-structuring of classification
• ii. shows genetic diverged from all other
life shortly after emergence of first cell
SHAPE
L. SHAPE
• 1. cocci = round
• 2. bacilli = rod
• 3. spirilli = spiral
M. CELL ARRANGEMENTS
• 1. diplo – pairs
• 2. strepto – chains
• 3. staphylo - bunches
N.GRAM STAINING
• 1. Gram positive stain violet –
•
a. lots of peptidoglycan in cell wall
• 2. Gram negative stain red, •
a. less peptidoglycan
•
b. outer membrane
•
PEPTIDOGLYCAN =
SUGARS CROSS-LINKED BY PEPTIDES
GRAM POSITIVE FORM ENDOSPORES
OUTER MEMBRANE =
RESISTANCE TO DRUGS
O. METABOLISM
• 1. Chemoheterotrophs –
•
E from bonds, organic C
•
parasites, saprobes, decomposers
• 2. Chemoautotrophs –
•
E from bonds, C from CO2
•
thermophilic bacteria, some of most
primitive. energy from iron or sulfur compounds
• 3. Photoautotrophs –
•
E from sun, C from CO2
•
cyanobacteria, stromatolites
•
P. GENE SEQUENCING
• 1. Shows bacteria diverged from all
other lineages shortly after first cells
appeared
Q. FLAGELLA
• 1. Bacteria
• a. ATP powered protein motor,
• b. hook & filament
• 2. Archaen :same design but
•
different proteins
• 3. Eukaryotic flagella
• a. Covered in membrane
• b. microtubules
• 4. Flagella of 3 domains:
•
Analogous structures
R. RESPONSE TO EXTERNAL SIGNALS
• 1. Signal transduction – extra cellular
signaling molecule binds to receptor and
initiates response
• a) taxis - innate behavioral response to
move toward or away from directional
stimulus
•
1. magnetotactic, 2. phototactic,
•
3. thermotactic,
4. geotactic
• b) kinesis- non-directional change in
activity in response to a stimulus.
• c) Quorum sensing: intercellular
communication
S. QUORUM SENSING
• 1. Bacteria use signaling molecules to
sense bacterial cell density
• 2. Signal molecules species specific
• 3. Sufficient signal mol. concentration
triggers communal response
•
a. gene expression activated,
•
b. proteins produced & excreted
• warning-video contains more facts than
you need to memorize. Just know the
slide.
• http://www.youtube.com/watch?v=YJWKWYQfSi0
EXTRA VIDEO ON QS IF
THERE IS TIME
• http://www.youtube.com/watch?v=nw2os1s0Hjw
• Start at 3:20 glowing bacteria/squid
• QS enables bacteria to co-ordinate their behaviour. As
environmental conditions often change rapidly,
bacteria need to respond quickly in order to survive.
These responses include adaptation to availability of
nutrients, defence against other microorganisms which
may compete for the same nutrients and the
avoidance of toxic compounds potentially dangerous
for the bacteria. It is very important for pathogenic
bacteria during infection of a host (e.g. humans, other
animals or plants) to co-ordinate their virulence in order
to escape the immune response of the host in order to
be able to establish a successful infection.
• Virulence factors are molecules expressed and secreted by pathogens (bacteria,
viruses, fungi and protozoa) that enable them to achieve the following:
• colonization of a niche in the host (this includes adhesion to cells) for example,
Trimeric Autotransporter Adhesins (TAA)
• Immunoevasion, evasion of the host's immune response
• Immunosuppression, inhibition of the host's immune response
• entry into and exit out of cells (if the pathogen is an intracellular one)
• obtain nutrition from the host.
• Virulence factors are very often responsible for causing disease in the host
because they are often responsible for converting non-pathogenic bacteria into
dangerous pathogens. In bacteria, virulence factors are often encoded on
mobile genetic elements, such as bacteriophages, and can easily be spread
through horizontal gene transfer. Some bacteria, such as Escherichia coli
O157:H7, gain the majority of their virulence from mobile genetic elements.
Strategies to target these specific virulence factors and mobile genetic elements
have been proposed
• Streptococcus lactis strep throat
• Staphylococcus aureas found on skin,
responsible for minor infections (like on
cuts/scratches)
• Bacillus tetani causes tetanus (lockjaw)
• Clostridium botulism causes botulism
• Yersinia (bacillus) pestis causes Black Plague
• Bacillus anthracis anthrax (forms endospores)
• Mycoplasmas very very tiny, cause of
pneumonia
• Rickettsia rickettsi link between bacteria and
viruses, can't reproduce outside host, causes
Rocky Mountain Spotted Fever
• Escherichia coli E. Coli - common bacteria of the
• Horizontal gene transfer (HGT) refers to the transfer of genes between
organisms in a manner other than traditional reproduction. Also termed
lateral gene transfer, it contrasts with vertical transfer, the transmission of
genes from the parental generation to offspring via sexual or asexual
reproduction. HGT has been shown to be an important factor in the
evolution of many organisms, including bacteria, plants and humans.
• Horizontal gene transfer is the primary reason for bacterial antibiotic
resistance,[1][2][3][4] and plays an important role in the evolution of
bacteria that can degrade novel compounds such as human-created
pesticides[5] and in the evolution, maintenance, and transmission of
virulence.[6] This horizontal gene transfer often involves temperate
bacteriophages and plasmids.[7] Genes that are responsible for
antibiotic resistance in one species of bacteria can be transferred to
another species of bacteria through various mechanisms (e.g., via Fpilus), subsequently arming the antibiotic resistant genes' recipient
against antibiotics, which is becoming a medical challenge to deal
with. This is the most critical reason that antibiotics must not be
consumed and administered to patients without appropriate
prescription from a medical physician