Introductory Microbiology - CCRI Faculty Web

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Feb 20, 2013 (4 years and 6 months ago)

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Introductory Microbiology

Dr. Heather Townsend

Characteristics of Life


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 double
-
membrane bound
nucleus
with DNA


contain membrane
-
bound
organelles


10

100 µm in
diameter


Characteristics of Cells

Prokaryotic cells


~1.0 µm in diameter


Bacteria and archaea


no nucleus


no membrane
-
bound
organelles


Microbiology


The study of of organisms
(
microorganisms

or
microbes
) too
small to be seen without magnification


This includes:

1.
Bacteria

2.
Viruses

3.
Fungi

4.
Protozoa

5.
Helminths (worms)

6.
Algae

The Microbes


1. Bacteria


Single
-
celled
organisms


Various shapes


Spherical


Rod


Spiral shapes


Cellular


Lack membrane
-
enclosed 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




The Microbes


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


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

The Microbes


6. Algae


Single
-
celled
microscopic
organisms


Have a nucleus and
many membrane
-
enclosed cellular
structures


Photosynthesize
their own food


Widely distributed in
fresh and salt water


Important source of
food for other
organisms

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


Domain


K
ingdom


P
hylum


C
lass


O
rder


F
amily


G
enus


s
pecies

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