Transcript Introductory Microbiology

Introductory Microbiology
Dr. Heather Townsend
Characteristics of Life
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Growth and development
Reproduction and heredity
Metabolism
Movement and/or irritability
Cell support, protection, and storage
mechanisms
• Transport of nutrients and waste
• Living things are made of cells!!
All cells…….
• Have an outer plasma membrane
• Contain DNA
– Enclosed within the cell somewhere
• Contain cytoplasm
– Everything between the plasma membrane
and the region of DNA
– Gives cells their shape
– Assist in movement of cell and organelles
Characteristics of Microbes
• Prokaryotic cells
– Smaller
– Lack special structures such as a nucleus and organelles
– All prokaryotic cells are microorganisms
• Some microorganisms are eukaryotic
• Viruses?
“Micro”organisms
Characteristics of Cells
Eukaryotic cells
– Animals, plants, fungi,
and protists
– contain doublemembrane bound
nucleus with DNA
– contain membranebound organelles
– 10–100 µm in
diameter
Characteristics of Cells
Prokaryotic cells
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~1.0 µm in diameter
Bacteria and archaea
no nucleus
no membrane-bound
organelles
Microbiology
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The study of of organisms
(microorganisms or microbes) too
small to be seen without magnification
This includes:
1.
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3.
4.
5.
6.
Bacteria
Viruses
Fungi
Protozoa
Helminths (worms)
Algae
The Microbes
• 1. Bacteria
– Single-celled
organisms
– Various shapes
• Spherical
• Rod
• Spiral shapes
– Cellular
– Lack membraneenclosed cellular
structures
– Widely distributed in
nature
Klebsiella pneumoniae,
bacteria that causes
pneumonia in humans
The Microbes
• 2. Viruses
– Acellular
– Composed of nucleic
acid and a few
proteins
– Replicate
themselves to
display other
properties of living
organisms when they
invade living cells
• 3. Fungi
– Yeasts and molds
• Single-celled,
microscopic
– Mushrooms
• Multicellular,
macroscopic
– Cell nucleus and
other cellular
structures
– Absorb nutrients
from their
environment
– Widely distributed in
water and soil
– Act as decomposers
of dead organisms
The Microbes
• 4. Protozoa
– Single-celled,
microscopic
organisms
– Have at least one
nucleus and many
cellular structures
– Obtain food by
engulfing or
ingesting smaller
organisms
– Most can move
– Found in many
different
environments
The Microbes
Amoeba
The Microbes
• 5. Helminths
– Large, multicellular
– Parasitize host
tissues
– Organs for
reproduction,
digestion,
movement,
protection
– Mouthparts
– Ingestion of larvae or
eggs in food
Tapeworm Head
• 6. Algae
– Single-celled
microscopic
organisms
– Have a nucleus and
many membraneenclosed cellular
structures
– Photosynthesize
their own food
– Widely distributed in
fresh and salt water
– Important source of
food for other
organisms
The Microbes
Micrasterias, a green algae living in
fresh water
General cell characteristics
• Locomotor appendages
• External boundaries
External Structures of Cells
• Locomotor appendages
– flagella
• long, sheathed cylinder containing
microtubules
• covered by an extension of the cell membrane
• function in motility
– cilia
• similar in overall structure to flagella
– shorter and more numerous
• found only on a single group of protozoa and
certain animal cells
• function in motility, feeding and filtering
External Boundary Structures
• Plasma (cell)
membrane
– typical bilayer of
phospholipids and
proteins
– serves as selectively
permeable barrier in
transport
External Structures of Cells
• Glycocalyx
– an outermost boundary that comes into direct contact
with environment
– usually composed of polysaccharides
– appears as a network of fibers, a slime layer or a
capsule
– functions in adherence, protection, and signal reception
– Beneath the glycocalyx:
• Fungi and most algae - cell wall
• Protozoa, a few algae, and all animal cells – cell
membrane
External Boundary Structures
• Cell wall
– Fungi
• thick inner layer of polysaccharide fibers
• composed of chitin or cellulose and a thin layer of mixed
glycans
– Algae
• varies in chemical composition
• substances include cellulose, pectin, mannans, silicon dioxide,
and calcium carbonate
– Bacteria!!!
• Dependent on cell wall composition
Prokaryote
Eukaryote
Branches of Study Within
Microbiology
• Immunology:
– studies immune chemicals and cells that are produced in response
to infection
• Public health microbiology & epidemiology:
– aim to monitor and control the spread of diseases (CDC)
• Food, dairy and aquatic microbiology:
– examine the ecological and practical roles of microbes in food and
water
• Biotechnology:
– ranges from bread making to gene therapy
• Genetic engineering & recombinant DNA technology:
– altering the genetic makeup of organisms
Microbes Are Involved In:
• nutrient production &
energy flow
– i.e., photosynthesis
• decomposition and nutrient
recycling
• production of foods, drugs
& vaccines
• bioremediation
• causing disease
Impact of Pathogens
• Pathogens
– Diseases-causing agents
• Nearly 2,000 different microbes cause
diseases in the human body
• 10 B infections/year worldwide
• 13 M deaths from infections/year worldwide
– killing about 1/3 of the U.S. population each
year
Impact of Pathogens
• Emerging diseases
– Becoming more prominent over the years
– Zoonosis
• SARS
• Reemerging
– Older diseases increasing in occurrence
• TB
• Malaria
• Hepatitis
Historical Microbiology
• 1546 – physician suggest that invisible
organisms may be involved with disease
• Abiogenesis vs biogenesis
Antonie van Leeuwenhoek
• First to observe living
microbes
• His single-lens
magnified up to 300X
(1632-1723)
Early Medical Microbiology
• Spontaneous generation
– “Living things arise from
nonliving things”
– Belief that some forms of life
could arise from vital forces
present in nonliving or
decomposing matter
– Debate over spontaneous
generation led in part to
development of scientific
method
Early Medical Microbiology
• Louis Pasteur:
– Worked in the wine industry
• Had knowledge about yeast
producing alcohol
– Swan-neck flasks
– Tipping the flask would allow
the microbes to enter the
infusion
• Cause them to become cloudy
• Main experiment that helped
disprove spontaneous generation
– Developed Pasteurization
– Developed a rabies vaccine
Early Medical Microbiology
• Robert Koch (~120 years
ago, German)
– Linked a microscopic organism
with a specific disease
(anthrax)
– Developed method to grow
bacteria in pure cultures
(cultures containing only one
kind of organism)
• Used solidified gelatin from
potato slices mixed with
agar
• Creates a firm surface that
microbes could grow on
Koch’s Postulates
1. The specific causative agent must be
found in every case of the disease
2. The disease organism must be
isolated in pure culture
3. Inoculation of a sample of the culture
into a healthy, susceptible animal must
produce the same disease
4. The disease must be recovered from
the inoculated animal
Early Medical Microbiology
• Oliver Wendell (American
physician)
– observed mothers who gave birth
at home experienced fewer
infections than those that gave
birth in a hospital
• Ignaz Semmelweis (Hungarian
doctor)
– showed that women became
infected with puerperal fever
during delivery by doctors coming
directly from the autopsy room
Early Medical Microbiology
• Joseph Lister (English surgeon)
– Introduced aseptic techniques
• Aimed at reducing microbes in a medial setting
and preventing wound infections
– Improved sanitation
• Promotes use of carbolic acid on bandages and
medical instruments
1900s
• Alexander Fleming
– observed that a species of Penicillium mold
killed bacterial cells
– led to the development of penicillin
• Two types of cells recognized!!!
Microbiology—Now
• Microbiology continues to face many challenges
– A pathogen can cause more than one disease
– Pathogens are becoming resistant to antimicrobials
– Pathogens can be used intentionally to infect large
numbers of people through bioterrorism
Science
• Scientific method
– 1. Observe some aspect of the natural world and ask
questions about it
– 2. Hypothesis
– 3. Make predictions
– 4. Test the predictions
– 5. Repeat the tests or develop new ones
– 6. Analyze and report the test results and conclusions
Microscopy
• Micrometer Size Range
– Most bacterial and archaeal cells are 1-5 micrometers
(µm) in length
How to view microbes?
• Light Microscopy
– Visible light passes through multiple lenses and through the
specimen
– Light microscopes usually have at least 3 lenses
• low-power
• high-power
• oil-immersion
How to view microbes?
• Staining techniques
– simple stain technique
– negative stain technique
– Special stains
Taxonomy
• Organizing, classifying and
naming living things
• In the mid-1700s, Carolus
Linnaeus published Systema
Naturae, establishing a
uniform system for naming
organisms
• Nomenclature gives scientific
names to organisms
• Identifying and classifying
organisms according to
specific criteria
Taxonomy
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Domain
Kingdom
Phylum
Class
Order
Family
Genus
species
3 Domains
• Eubacteria
– true bacteria
– peptidoglycan
• Archaea
– odd bacteria that live in extreme environments
– high salt, heat, etc. (usually called extremophiles)
• Eukarya
– have a nucleus & organelles
– Protista
• Algae
– Fungi
– Plantae
– Animalia
Naming “Most” Micoorganisms
• Binomial (scientific) nomenclature
• Gives each microbe 2 names:
– Genus - noun, always capitalized
– species - adjective, lowercase
• Both italicized or underlined****
– Staphylococcus aureus (S. aureus)
– Bacillus subtilis (B. subtilis)
– Escherichia coli (E. coli)
What to expect……..
• Different microorganisms
• How to detect microorganisms
• Common disease caused by
microorganisms
• How to control the spread of
microorganisms
• Immune system