Living organisms
verses inanimate
objects
Characteristics
of living
organisms
Maintaining life processes
• Normal vital functions
– Body systems operating to obtain oxygen,
nutrients,
– Responding to environment and adapt to
environmental stimuli
• Maintaining life in disease
– Treatments
– Biomedical Devices
First do no harm
Supporting life
processes
What is death?
What is living?
What are characteristics of life?
1.
2.
3.
4.
5.
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___________________
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Microbes can cause disease in
animals
The microorganisms shown
here are: A, the bacterium
Escherichia coli; B, a
photosynthetic
cyanobacterium; C, a fungus;
D, Ebola virus; E, the
protozoan malaria parasite.
(Sources: B, Mike Clayton; CE, CDC). Note that the scale
on each of these pictures is
different.
Infectious disease
• In the U.S., infectious diseases have been
significantly diminished over the last 150
years (small pox, dysentery, leprosy, etc.)
• Developing nations are still battling
disease problems (Haiti)
• New diseases have appeared (AIDS) that
present different problems
Year
Microbe/disease
Type
Health problem
1973
Rotavirus
Virus
Major cause of infantile
diarrhea worldwide
1975
Parvovirus B19
Virus
Severe anemia
1976
Cryptosporidium parvum
Parasite
Acute and chronic diarrhea
1977
Ebola
Virus
Ebola hemorrhagic
fever/uncontrolled bleeding
and kidney failure
1977
Legionella pneumophila
Bacteria
Legionnaireþs disease
1977
Hanta virus
Virus
Hemorrhagic fever
1977
Campylobacter jejuni
Bacteria
Short-term diarrhea
1980
Human T-lymphotropic
virus I (HTLV-I)
Virus
T-cell lymphoma-leukemial
cancer of the blood
1981
Toxic strains of
Staphyloccus aureus
Bacteria
Toxic shock syndrome
1982
Escherichia coli O157:H7
Bacteria
Hemorrhagic colitis;
hemolytic uremic syndrome
1982
HTLV-II
Virus
Hairy cell leukemia
1982
Borrelia burgdorferi
Bacteria
Lyme disease
1983
Human immunodeficiency
virus (HIV)
Virus
Acquired immune
deficiency syndrome
(AIDS)
1983
Helicobacter pylori
Bacteria
Peptic ulcer disease
1985
Entercytozoon bieneusi
Parasite
Persistent diarrhea
1986
Cyclospora cayetanensis
Parasite
Persistent diarrhea
1988
Human herpesvirus-6
(HHV-6)
Virus
Roseola subitum/skin rash
1988
Hepatitis E
Virus
Liver infection; epidemic
hepatitis
1989
Ehrlichia chaffeensis
Bacteria
Human
ehrlichiosis/influenza-like
infection
1989
Hepatitis C
Virus
Chronic liver infection
1991
Guanarito virus
Virus
Venezuelan hemorrhagic
fever
1991
Encephalitozoon hellem
Parasite
Conjunctivitis
Parasite
Atypical
babesiosis/infection with
fever, chills and fatigue
1991
New species of Babesia
Microorganisms
• Microbes make up the major portion of the biomass
present on the Earth. Therefore, the nutrients they eat
and the products they form greatly influence the
environment.
• Cyanobacteria and algae in the oceans are responsible
for most photosynthesis and are a major sink for carbon
dioxide, a greenhouse gas.
• Microbes release nutrients from dead organisms, making
them available to the rest of the ecosystem.
• Some microbes play a role in the production of energy,
while other microbes interfere with energy production.
Helpful and harmful
Microorganisms played an important role in removing many of the pollutants released
during the Exxon Valdez oil spill in Prince William Sound. Interestingly, microbes were
not added to the site, but the clean-up relied on bacteria from that environment. A
nutrient solution was sprayed onto the oil to encourage the growth of oil-degrading
microbes. Though this was one of the more successful methods used to clean up the
oil, but no treatment removed all of the pollutants.
What is disease?
• Ignaz Semmelweis showed that child-bed fever was
spread by physicians and could be prevented by careful
hand washing with chloride of lime (1861).
• Louis Pasteur, while working on sour wine, discovered
that unwanted microbes were infecting the wine. He
correctly deduced that infectious disease was caused by
similar infections with harmful microbes (1865).
• Robert Koch was the first to isolate a disease-causing
microbe, Bacillus antrhacis. In the process he developed
techniques and standard protocols for defining the cause
of a disease (1876).
Robert Koch (1876)
• A set of rules for the assignment of a microbe as the
cause of a disease:
– The specific organism should be shown to be present in all
cases of animals suffering from a specific disease, but should
not be found in healthy animals.
– The specific microorganism should be isolated from the diseased
animal and grown in pure culture on artificial laboratory media.
– This freshly isolated microorganism, when inoculated into a
healthy non-immune laboratory animal, should cause the same
disease seen in the original animal.
– The microorganism should be reisolated in pure culture from the
experimental infection.
FUNDAMENTALS
• Microbes are useful tools in research because of their
rapid life cycle, their simple growth requirements, and
their small size.
• Due to this simplicity, microbes have been essential in
understanding core questions in biology.
• Attempts to classify microorganisms have lead to a
classification system that divides all organisms into three
domains of life: Archaea, Bacteria, and Eukarya.
• Microbes provide tools for use in molecular biology.
These tools have allowed scientists to make rapid
progress in investigating many types of microorganisms.
Relative size of microbes
Prokaryote and Eukaryote Cells
•
•
•
•
•
•
•
•
•
Both have DNA as their genetic material (it’s
DNA that tells cells what kind of cells they
should be).
Both are covered by a cell membrane.
Both contain RNA.
Both are made from the same basic
chemicals: carbohydrates, proteins, nucleic
acid, minerals, fats and vitamins.
Both have ribosomes (the structures on
which proteins are made).
Both regulate the flow of the nutrients and
wastes that enter and leave them.
Both have similar basic metabolism (life
processes) like photosynthesis and
reproduction.
Both require a supply of energy.
Both are highly regulated by elaborate
sensing systems ("chemical noses”) that
make them aware of the reactions within
them and the environment around them.
Differences
•
•
•
Eukaryotic cells contain two important things
that prokaryotic cells do not: a nucleus and
organelles (little organs) with membranes
around them.
DNA arrangement
Although both eukaryotic and prokaryotic
cells contain DNA, the DNA in eukaryotic
cells is held within the nucleus. In
prokaryotic cells, the DNA floats freely
around in a unorganized manner.
Presence of organelles
The organelles in eukaryotic cells allow
them to perform more complex functions
than prokaryotic cells, which donot have
these little organs.
•
Some of the organelles in eukaryotic cells are:
–
The Nucleus – the “brain” or control center of the cell. It contains
DNA, which makes up genes. That DNA gets transcribed, or copied
onto messenger RNA. That messenger carries a copy of the genes
orders for certain protein production. These orders go to the protein
factories.
–
Ribosomes – These are the protein factories. They follow
instructions from messenger RNA (remember that the messenger
RNA got its orders from the DNA). The instructions tell the
ribosomes to make specific proteins. Note, this particular organelle is
found in prokaryotes too!
–
Endoplasmic Reticulum (ER) – structures that modify proteins
produced in the ribosomes. Not all of the proteins made by the
ribosomes need changing, but those that do get “altered” here.
–
Golgi Apparatus – This structure will make even more changes to
the proteins that already got changed when they were in the E.R.
Remember those proteins were made in the ribosomes, changed
once in the E.R. and will be changed again in the Golgi Apparatus.
The Golgi also acts as a post office by packaging and shipping
proteins to other parts of the cell or out of the cell.
–
Mitochondria – structures which produce the cell’s energy, a.k.a.
powerhouses of the cell.
–
Chloroplasts – structures which allow plants to trap sunlight and
carry out photosynthesis.
Eukaryotes
•
•
•
•
Size
Eukaryotic cells are, on average, ten times larger
than prokaryotic cells.
Cell Wall Differences
Prokaryotic cells have a cell wall composed of
peptidoglycan (amino acid and sugar). Some
eukaryotic cells also have cells walls, but none that
are made of peptidoglycan.
Flagella Arrangement
The flagella in eukaryotic cells are different from the
flagella in prokaryotic cells. Flagella are the
structures that help cells move (scientists call it
motility). The flagella in eukaryotic cells are
composed of several filaments and are far more
complex than the flagella in prokaryotic cells.
All cells have their genes arranged in linear chains
called chromosomes, but eukaryotic cells contain
two (or more) copies of every gene. During
reproduction, the chromosomes of eukaryotic cells
undergo an organized process of duplication called
mitosis.
Prokaryotes or Procaryotes
• Groups of organisms that lack cell nucleus
Typical cell structure of a
eubacterium
• They do not have true nuclei containing DNA
• Prokaryotes have a larger surface area to volume ratio
giving them a higher metabolic rate, a higher growth rate
and consequently a shorter generation time when
compared to prokaryotes.
The Procaryotes
Archaebacteria
Eubacteria
Prokaryotes
• Typically envisaged to be unicellular but are capable of
forming stable aggregate communities
• Communities are often encased in a stabilizing polymer
matrix (slime) called biofilms, capable of doing cell to cell
signaling
• Originally in biology, the distinction between prokaryotes
and eukaryotes were so great that it was the basis for a
2 tier grouping for cells
– A criticism of this classification is that the word "prokaryote" is based on
what these organisms are not (they are not eukaryotic), rather than what
they are (either archaea or bacteria)
– This arrangement of Eukaryota (also called "Eukarya"), Bacteria, and
Archaea is called the three-domain system replacing the traditional twoempire system
Gram positive and gram
negative bacteria
• Gram positive and gram negative refers
to how a bacteria reacts to a gram stain. If
it takes the initial stain, it will be purple
and be considered gram positive. If it
doesn't take the initial stain, it will be pink
and gram negative. The difference is the
outer casing of the bacteria. A gram
positive bacteria will have a thick layer of
peptidoglycan (a sugar-protein shell) that
the stain can penetrate. A gram negative
bacteria has an outer membrane covering
a thin layer of peptidoglycan on the
outside. The outer membrane prevents
the initial stain from penetrating.
Gram Positive or negative
•
There are two distinct types of bacteria based on
the structural differences of their cell walls. Grampositive bacteria will retain the crystal violet dye
when washed in a decolorizing solution. The
pathogenic capability of Gram-negative bacteria
is often associated with certain components of
Gram-negative cell walls, in particular the
lipopolysaccharide (also known as LPS or
endotoxin) layer.[1] In humans, LPS triggers an
innate immune response characterized by
cytokine production and immune system
activation. Inflammation is a common result of
cytokine (from the Greek cyto, cell and kinesis,
movement) production, which can also produce
host toxicity.
Gram negative
•
•
•
•
The proteobacteria are a major group of Gram-negative
bacteria, including Escherichia coli, Salmonella, Shigella,and
other Enterobacteriaceae, Pseudomonas, Moraxella,
Helicobacter, Stenotrophomonas, Bdellovibrio, acetic acid
bacteria, Legionella and alpha-proteobacteria as Wolbachia
and many others. Other notable groups of Gram-negative
bacteria include the cyanobacteria, spirochaetes, green
sulfur and green non-sulfur bacteria.
Medically relevant Gram-negative cocci include three
organisms, which cause a sexually transmitted disease
(Neisseria gonorrhoeae), a meningitis (Neisseria
meningitidis), and respiratory symptoms (Moraxella
catarrhalis).
Medically relevant Gram-negative bacilli include a multitude
of species. Some of them primarily cause respiratory
problems (Hemophilus influenzae, Klebsiella pneumoniae,
Legionella pneumophila, Pseudomonas aeruginosa),
primarily urinary problems (Escherichia coli, Proteus
mirabilis, Enterobacter cloacae, Serratia marcescens), and
primarily gastrointestinal problems (Helicobacter pylori,
Salmonella enteritidis, Salmonella typhi).
Gram-negative bacteria associated with nosocomial
infections include Acinetobacter baumannii, which cause
bacteremia, secondary meningitis, and ventilator-associated
pneumonia in intensive care units of hospital establishments.
Gram-negative
Pseudomonas aeruginosa
bacteria (pink-red rods).
Treatment
•
The following treatments are
recommended:
–
–
–
–
Azithromycin 1 gram oral as a single dose, or
Doxycycline 100 milligrams twice daily for seven
to fourteen days.
Tetracycline
Erythromycin
Gram positive
•
Gram-positive bacteria are those that are
stained dark blue or violet by Gram
staining. This is in contrast to Gramnegative bacteria, which cannot retain the
crystal violet stain, instead taking up the
counterstain (safranin or fuchsin) and
appearing red or pink. Gram-positive
organisms are able to retain the crystal
violet stain because of the high amount of
peptidoglycan in the cell wall. Grampositive cell walls typically lack the outer
membrane found in Gram-negative
bacteria.
Gram stain for anthrax
Gram positive bacteria
• The following characteristics are generally
present in a Gram-positive bacterium:[2]
– cytoplasmic lipid membrane
– thick peptidoglycan layer
• teichoic acids and lipoids are present, forming
lipoteichoic acids which serve to act as
chelating agents, and also for certain types of
adherence.
– capsule polysaccharides (only in some species)
– flagellum (only in some species)
Gram positive bacteria
Treatment
•
•
Studies have also shown that the broader-spectrum of
antibiotics offer more effective short treatment courses
than the traditional 10 days of Penicillin V,[30] but
noted that "widespread use of broad-spectrum agents
for a common infection is a significant concern in an
age of increasing bacterial antibiotic resistance".[31] It
is important to complete the full course of antibiotics to
prevent rheumatic fever or an abscess on the tonsils.
In one report of 500 patients, 30% had group A betahemolytic streptococcal pharyngitis, 0.2% had
rheumatic fever and 0.2% had peritonsillar abscess
(an abscess on the tonsils).[6]
Azithromycin and other macrolides have been used to
treat strep throat in penicillin-sensitive patients,
however macrolide resistant strains of GAS are not
uncommon. In these strains, cross-resistance to
macrolides, lincosamides, and streptogramins is
possible.
Experiments for Home and
Classroom
•
•
This site provides an excellent description of prokaryotic and eukaryotic
cells and allows students to conduct "cell learning" experiments using
common household objects such as Tupperware™ containers, Ziploc™
bags, applesauce, marshmallows, spaghetti and breakfast cereal. Click:
http://stars.eng.usf.edu/genetic%20engineering%20module/TheCellPo
werHouse.doc
This site offers virtual tours of the component parts (the structure and
organelles) of both kinds of cells. It also contains a great deal of interesting
material presented in an easily understandable way. Go to this site and click
on the topic that interests you or your students most:
http://www.cellsalive.com/cells/3dcell.htm
In this activity, students are invited to create a booklet explaining cell theory,
the function of organelles and cell membrane processes. Materials needed
include index cards, pictures of cellular organelles, yarn or string and
markers.
There are both online and printable versions. Click:
http://micro.magnet.fsu.edu/cells/plantcell.html
The protists or protozoans
Malaria is caused by four species
of protozoan parasites
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malaria
Trichomonads
Budding yeast
• Beer!
• Bread
• Candidiasis –
sometimes called
thrush or yeast
infections, can be
very serious in
immunodeficient
patients
Plants – cells contain
chloroplasts and carry out
photosynthesis,
i.e. convert sunlight CO2 and
H20 to sugars
Animals
Invertebrates – do not have a backbone
Vertebrates do have a backbone
The Life Cycle of Influenza Virus
ATP
• Adenosine-5'-triphosphate (ATP) is a
multifunctional nucleotide used in cells as
a coenzyme. It is often called the
"molecular unit of currency" of intracellular
energy transfer.[1] ATP transports chemical
energy within cells for metabolism.
Life is all about energy - ATP
• Cellular Respiration: is the process that
releases energy by breaking down food
molecules in the presence of oxygen.
• Aerobic respiration occurs in the
mitochondria.
• Energy that is released by breaking food
down is stored as ATP,
• ATP is a short-term energy storage molecule
• Cells use as ATP as their energy source.
Cell reproduction
DNA
• Deoxyribonucleic acid
(DNA) is a nucleic acid that
contains the genetic
instructions used in the
development and functioning
of all known living organisms
and some viruses. The main
role of DNA molecules is the
long-term storage of
information.
Reproduction in procaryotes
Binary fission, or
prokaryotic fission, is the
form of asexual reproduction
and cell division used by all
prokaryotic and some singlecelled eukaryotic organisms.
This process results in the
reproduction of a living
prokaryotic cell by division into
two parts which each have the
potential to grow to the size of
the original cell.
Binary fision
•
Binary fission begins with DNA replication. DNA replication
starts from an origin of replication, which opens up into a
replication bubble (note: prokaryotic DNA replication
usually has only 1 origin of replication, whereas
eukaryotes have multiple origins of replication). The
replication bubble separates the DNA double strand, each
strand acts as template for synthesis of a daughter strand
by semiconservative replication, until the entire prokaryotic
DNA is duplicated.
The cell cycle. Image from Purves et al., Life: The
Science of Biology, 4th Edition, by Sinauer
Associates (www.sinauer.com) and WH Freeman
(www.whfreeman.com)
Mitosis
Mitosis –
The four
phases of cell
division
•Prophase
•Metaphase
•Anaphase
•Telophase
Development
So what’s a stem cell?
• Stem cells are cells found in most, if not all, multi-cellular
organisms. They are characterized by the ability to renew
themselves through mitotic cell division and differentiating into a
diverse range of specialized cell types.
• The two broad types of mammalian stem cells are: embryonic stem
cells that are isolated from the inner cell mass of blastocysts, and
adult stem cells that are found in adult tissues. In a developing
embryo, stem cells can differentiate into all of the specialized
embryonic tissues. In adult organisms, stem cells and progenitor
cells act as a repair system for the body, replenishing specialized
cells, but also maintain the normal turnover of regenerative organs,
such as blood, skin, or intestinal tissues.
Stem Cells
* Embryonic stem
cell come from early
embryos – are
totipotent
* umbilical cord
stem cells are
multipotent.
* Adult stem cells
are multipotent
Mouse embryonic stem cells
H&E section of a lung tumor
with characteristic
histopathology of a poorly
differentiated carcinoma
Cancer
Acorns, Mice, Ticks = Lyme Disease
• Acorns are an important food source for many forest
animals, including mice
• Large crops of acorns in the fall lead to a booming
mouse population the following summer.
• Forest-living mice carry a spiral-shaped bacteria called
Borrelia burgdorferi which causes Lyme disease.
• As the population of mice increases the incidence of
Lyme disease outbreaks increase.
• Tick larvae feed on the mice and pick up bacteria.
• More mice increase the number of infected ticks by
providing tick larvae with more opportunities to pick up
bacteria during feeding.
• These larvae ultimately feed on humans or other animals
and the rate of Lyme disease increases
Biofilms
sheets or layers of bacteria on surfaces
very difficult to penetrate or treat
Pathogen
Host
Virulence
Factors
Immune
Defenses
Adhesins
Innate response
Toxins
Biofilm/capsule
Inflammation
Adaptive response
Overview – Know your weapons
• Physical barriers
• Primary lymphoid
organs – Thymus and
bone marrow
• Secondary lymphoid
organs
- l. n. spleen, and MALT
Types of Immunity
• Innate or
nonspecific
immunity
• Adaptive or
acquired
immunity
– Humoral
Immunity
– Cell mediated
immunity
Nonspecific immune response
Specific or Acquired Immunity
Antigens and Antibodies
How do we keep from getting
sick?
• Variolation, immunization against smallpox, was a
common practice before vaccination was common. This
worked because the patient was exposed to a weak
strain of smallpox, which did not kill, yet provided
immunity to the disease.
• Edward Jenner discovered that cowpox could protect
against smallpox, with a much lower incidence of
complications than variolation.
• Pasteur discovered a general method for immunizing
people against disease while working on chicken
cholera. He coined the term vaccination to describe the
technique.
What about if we are sick?
• Paul Ehrlich spent 17 years in search of a
chemical treatment against syphilis,
eventually discovering salvarsan.
• Alexander Fleming discovered the first
antibiotic, penicillin.
So to our assignment