Transcript Bacteria & Viruses - St. Mary Catholic Secondary School

Bacteria & Viruses
Also Known As…
Why We Beat the Aliens at the
End of “War of the Worlds”
Bacteria – Basic Info
• Bacteria were the first forms of life on
the planet. They arose from the
organic soup of the primordial Earth.
• There are several characteristics that
all bacteria have in common:
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Unicellular (fancy talk for “single-celled”.)
Prokaryotic – you know this…
Organelles are not membrane bound.
Single circular chromosome.
Reproduce asexually by binary fission.
• Bacteria make up both the
archaebacteria and eubacteria
kingdoms – it used to be one – Monera.
Structure of Bacteria
• DNA – Genetic
Material
• Cell Wall – Protection
• Cell Membrane – In &
Out of Cell
• Cytoplasm – Fluid
interior
• Ribosomes – Protein
builders
• Pili – Connect & Trade
DNA
• Flagella – Movement
Bacterial Shapes
• Cocci – Spherical
• Bacilli – Rod-shaped
• Sprilli – Spirals
Prefixes
• No prefix – Solo
• Diplo – Pairs
• Strep - Chains
• Staph - Clusters
Gram Stain & Bacteria
• Gram stain is a concoction of crystal
violet and iodine – it will react with the
cell wall of certain bacteria.
• Gram-positive bacteria retain the gram
stain and appear dark purple. These
bacteria a very common and usually not
bad – less pathogenic.
• Gram-negative bacteria do not react with
the stain and appear light pink. These
bacteria are less common but they are
more pathogenic and are a serious threat
to your health. (Meningitis, gonorrhea
and peumonia.)
Gram Stain & Bacteria
• Gram positive
anthrax bacilli in
cerebrospinal
fluid.
• Gram negative
bacilli bacteria.
Nutrition
Autotrophic
• Make their own
energy compounds.
• Photoautotrophs – use
photosynthesis –
energy in sunlight.
• Chemoautotrophs –
gain energy from
simple inorganic
compounds.
Heterotrophic
• Must consume other
materials to gain
energy.
• Symbiotes – bacteria
live in close
association with host.
• Parasites – live in host
– negative effects.
• Saprobes – eat dead
and/or decaying
matter.
Bacterial Respiration
Anaerobic
• Anaerobic
respiration does not
require oxygen to
make energy (ATP).
• Obligate anaerobes
must live in the
absence of oxygen.
Oxygen is toxic to
them and will kill
them if present.
• Facultative
anaerobes do not
use oxygen but can
survive just fine if it
is around.
Aerobic
• Aerobic respiration
requires oxygen to
make ATP.
• Obligate aerobes
must have oxygen to
make ATP or they
die. They can not
live in the absence
of oxygen.
Reproduction – Binary Fission
Reproduction – Conjugation
Bacterial Cryogenic Chambers
• When growth conditions become
extremely unfavourable, many grampositive bacteria form endospores.
• Endospores are thick walls that
surround the DNA and cytoplasm of the
bacteria.
• The bacteria goes into a dormant
phase until the environment is more
favourable. An endospore may last for
months.
Bacterial Kingdoms
Archaebacteria
• Old school bacteria
from the harshest
places on Earth that
resemble the
primordial Earth.
• Methanogens –
release methane gas
(CH4).
• Thermophiles – live
in very hot places.
• Halophiles – live in
very high
concentrations of
salt.
Eubacteria
• Most of the
prokaryotes on
Earth are
eubacteria.
• They inhabit almost
all places on Earth
and show a great
deal of diversity
within the kingdom.
Viruses
Viruses – Basic Info
• A virus is a non-cellular
piece of genetic material
surrounded by protein
that lives within a host
cell.
• Viruses are not part of
any of the six kingdoms.
• Viruses are classified
according to their
structure and the type of
host cell they inhabit.
• The word “virus” means
poisonous slime of plant
or animal origin.
To Live or Not To Live…
Evidence: Living
• Has biomolecules
like proteins and
nucleic acids.
• Has DNA or RNA.
• Capable of
directing
reproduction.
• Able to evolve.
• Able to respond.
Evidence: Non-living
• Not made of cells.
• Can not grow or
reproduce outside
of host cell.
• Can’t run protein
synthesis without
host cell.
• Lacks enzymes for
cellular
respiration.
The Lytic Life Cycle
1. Virus attaches to
host cell.
2. Viral DNA is
injected.
3. Viral DNA uses
host cell
machinery to
make viral parts.
4. Viral parts are
assembled.
5. Enzyme created to
destroy host cell’s
cell wall – lysis!
The Lysogenic Life Cycle
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Virus attaches to host cell.
Viral DNA is injected.
Viral DNA is incorporated into the bacterial
chromosome and go into a dormant state.
Bacteria will often not notice the change to
its genetic content and divide several times
over. (Making a copy of the viral DNA as it
does).
A change occurs whereby the viral DNA
uses host cell machinery to make viral
parts.
Viral parts are assembled.
Enzyme created to destroy host cell’s cell
wall – lysis!
The Lysogenic Life Cycle
That’s All I Got…