Viruses & Bacteria
Chapter 17
Biology 11
Presentation put together by Mandie Lynn Walls
What are Viruses
A virus is a non-cellular particle made
up of genetic material and protein
that can invade living cells.
T4 Bacteriophage
Herpes Virus
Escherichia Coli Bacterium
E. coli is a bacterium. That is a crude cell, it is not a virus
because viruses are protein containers with DNA cores or
RNA cores.
E. Coli and the
Bacteriophage
What it looks like in real life
The Structure Of a Virus
Viruses are composed
of a core of nucleic
acid
 The Nucleic acid core
is surrounded by a
protein coat called a
capsid
 The Nucleic core is
either made up of
DNA or RNA but
never both

Cycle of Lytic and Lysogenic
Vaccines
► Viruses
grown on chicken embryos are
attenuated vaccines
► Another type of vaccine is made by heat
killing the virus
Retrovirus


Change DNA
into RNA.
Example of a
Retrovirus is
HIV
A typical, "minimal" retrovirus
consists of:
•an outer envelope which
was derived from the plasma
membrane of its host
•many copies of an envelope
protein embedded in the lipid
bilayer of its envelope
•a capsid; a protein shell
containing
•two molecules of RNA and
•molecules of the enzyme
reverse transcriptase
Bacteria Cell
Prokaryotes





Cells that do not have a
nucleus
Exist almost every where on
earth
Grow in numbers so great you
can see them with the unaided
eye
Are placed in either the
Eubacteria or the
Archebacteria Kingdoms
Make up the smaller of the two
kingdoms
Eubacteria
Make up the larger of
the two prokaryote
kingdoms
Generally are
surrounded by a cell
wall composed of
complex
carbohydrates
Cyanobacteria






Photosynthetic
bacterium
Bluish-greenish color
Contain membranes
that carry out the
process of
photosynthesis
Do not contain the
same type of
chloroplasts as plants
do
This bluish-greenish
algae can be found
nearly everywhere on
earth.
Can survive in
extremely hot
environments and even
extremely cold
environment
Archaebacteria
 Lack important
carbohydrate found
in cell walls
 Have different lipids
in their cell
membrane
 Different types of
ribosomes
 Very different gene
sequences
 Archaebacteria can
live in extremely
harsh environments
 They do not require
oxygen and can live
in extremely salty
environments as well
as extremely hot
environments.
Identifying Prokaryotes
Cell Shape
Cell Wall
Movement
Bacterium Shapes




Cocci~ Sphere shaped
bacteria
Bacillus~ Rod shaped bacteria
Spirrillium ~ Spiral shaped
bacteria
Flagella~ Leg-like structures
that help to propel the
bacterium.
Gram + and Gram – Bacterium
Cell Walls
Cellular Walls


Chemical nature of a cell wall can be determined
by Gram Staining
By finding out what color the cell produces when
it is gram stained you can figure out the type of
carbohydrates in the cell wall
Movement
• Flagella ~ Tail like structure
the whips around to propel the
bacterium
• Cillia ~ Miniature flagella
surround the cell that help to
“swim”
• Non motile ~ Sticky cillia like
structures that keep the
bacterium from moving
Flagella
Bacteria and their energy
 Autotrophs
 Chemotrophs
 Heterotrophs
Autotrophs
Make their own
energy
 Using Solar energy
 Eg. Cyanobacteria

Chemotrophs



Make own Energy
Using Chemical energy
Eg. Archaebacteria
Heterotrophs



Obtain food
By eating
Eg. E-coli
Bacteria Respiration


Obligate Anaerobes
Facultative Anaerobes

Obligate Aerobes



Live without Oxygen
Can live with or
without oxygen
Cannot live without
oxygen.
Bacteria Reproduction



Binary Fission
Conjugation
Spore Formation
Cellular organism copies it’s genetic information then splits into
two identical daughter cells
Conjugation


A type of Bacteria Sex
Two organism swap
genetic information,
that contains the
information such as a
resistance to penicillin
Spore Formation: Endospore
 A type of dormant cell
 Exhibit no signs of life
 Highly resistant to
environmental stresses such
as:
-High temperatures
-Irradiation
-Strong acids
-Disinfectants
 Endospores are formed by
vegetative cells in response
to environmental signals that
indicate a limiting factor for
vegetative growth, such as
exhaustion of an essential
nutrient.
Symbiosis


Close relationship
between to species in
which at least one
species benefits from
the other
Live together for LIFE
Parasitism


Bacteria exploit the
host cell, injuring
them
Eg. Mychobacterium
tuberculosis
Mutualism


Symbiosis in which two
of the species live
together in such a way
that both benefit from
the relationship
Eg. E-coli
Nitrogen Fixations
Process by which nitrogen in the
atmosphere is converted into a form that
can be used by living things
THE END
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