Download Bacteria and Viruses

The Cell Theory
Bacteria and
Viruses
Two Types of Cells
• Prokaryotes (pro = before, karyote = nucleus)
cells lack internal membrane structures
 Do not have a membrane bound nucleus
 Just bacteria
• Eukaryotes (eu = true, karyote = nucleus) cells
have internal membrane structures
 Do have a membrane bound nucleus
 Fungus, protists, plants and animals
Kingdom Monera
• All bacteria are prokaryotic
• Unicellular organisms
• Heterotrophs, Autotrophs or Chemotrophs
(or a combination)
• Two Kingdoms
 Archeabacteria - Live in extreme conditions
(extreme hot/cold, very acidic/basic, very salty
conditions).
 Eubacteria - Live generally in conditions that we
are exposed to every day
1. All living things are made of one
or more cells
2. Cell is basic unit of organization
3. Cells come from preexisting cells
How Cells Acquire Energy
• Autotrophs - Make their own food through
 Plants, algae and photosynthesis
 Cyanobacteria and Nitrogen Fixation
• Heterotrophs - Obtain food through other organisms
 Animals eat
• Chemotrophs - Obtain food through chemicals such as
sulphur
 Create energy
• Saprophytes - Obtain food through dead matter by
decay
 Bacteria
• Decomposers - Obtain food through break down of
dead and decaying matter
Bacteria Structure
• Capsule
 Keep from drying out
 Protect from
phagocytosis
 Disease-causing
bacteria such as
Escherichia coli and
Streptococcus
pneumoniae
 Non-encapsulated
mutants are a-virulent
(don't cause disease)
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Bacterial Structure
Bacterial Structure
• Cell Membrane
• Barrier that lets
some things
and keeps
others out
• Made of a
double lipid
(fat) layer.
 Cell Wall
 Enclosed by rigid cell wall
composed of peptidoglycan
• a protein-sugar
(polysaccharide) molecule
 Gives cell shape and
surrounds cell membrane,
protecting it from
environment
 Two Types - Gram Positive
and Gram Negative
PEPTIDOGLYCAN
Bacterial Structure
• Cytoplasm - fluid filled inside
of all cells
• Plasmids - extra cellular DNA
help bacteria to communicate
to each other
• Flagella - whip like tail helps
bacteria move
• Cilia - hair like structures
help bacteria move
• DNA - double circular strand
• Ribosome - made from DNA
and help make proteins for
cell structure and function
Plasmids
• A circular piece of
replicating DNA not
of the genome of
bacteria
• Originally evolved
by bacteria
• May express
antibiotic resistance
or be modified to
express proteins of
interest
What is transformation?
• Uptake of foreign DNA, often
a circular plasmid
Plasmid
Cell wall
Bacterial
chromosomal
DNA
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Bacterial Reproduction
• Binary Fission - asexual reproduction
 One copies DNA
 Buds off making identical copy of itself
• Pilus - structure help transfer DNA or
plasmids to another bacteria
 Diversification
• Endospores - copies made by binary
fission and stored in parent cells
Bacterial Arrangements
• Strepto - More than two in a chain
 Streptococcus pyogenes
 Streptobacillus acidaphyllus
• Staphylo - More than two in a cluster
 Staphylococcus aureus
• Diplo - Two grouped together
 Diplococcus pneumonia
• Tetra - Four group together
 Escherichia coliform
How we fight the off?
• Antibiotics - biologically made
chemicals
 Penicillin - fights gram positive bacteria by
preventing them from making a cell wall.
 Streptomycin - fights gram negative
bacteria by preventing them from making
proteins
 Sulpha Drugs - fight a broad spectrum of
bacteria by inhibiting their metabolism.
Bacterial Shapes
• Cocci - are circular shaped bacteria
 Streptococcus pyogenes
• Bacillus - are rod shaped bacteria
 Bacillus anthrasis
• Spirillum (spiralchetes)
 Spirillum minus (rat bite fever)
Identification Techniques
• Streaking - uses petri dishes to spread bacteria
on a growth media
• Incubation - a type of oven used to grow
bacteria streaked plates over time
• Smear - uses a slide to smear bacterial sample
for indetification
• Fix -heat used to adhere bacteria to slide
• Wet Mount - water used to suspend onto a slide
• Simple Stain - uses one stain to see shapes and
arrangements
• Compound Stain -uses two or more stains to see
what type of bacteria (grams stain)
Types of Infections
• Epidemic - a localized infection
• Pandemic - a world wide
infection
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Viral Reproduction
• Lysogenic Cycle - Retroviruses
 Work their way into cell and force their DNA
into DNA of host cell
 Called provirus stage - host makes copies of it’s
DNA, but also virus DNA
 Can convert to lytic cycle
• Lytic Cycle  All viruses must Lyse cells to get copies to
external environment to further reproduction
Microscopes as Tools
• Enable to see objects too small to
examine with just our eyes
• Microscopes magnify, contrast and
resolve images of an object
 Magnification - ability to make image look
larger
 Contrast - ability to distinguish between
light and dark parts of an image
 Resolution - ability to distinguish between
two points of an image
Types of Microscopes
1. Compound Light
2. Scanning Light
(stereo)
3. Transmission
Electron
4. Scanning Electron
5. Scanning-Tunneling
Electron
Microscopes
• Light Microscopes
 Magnify cells 1000 time
original size
 View live specimens
 See large things inside
cells
• Electron Microscopes
 Magnify cells 100,000x
original size
 View only dead cells
 View things smaller than
cells
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