Download What Are Bacteria?

Characteristics
Benefits
Negative Effects
What Are Bacteria?
 Bacteria are single-
celled organisms.
 They do not contain a
membrane-bound
nucleus.
 They do not contain
membrane-bound
organelles.
What DO They Have?
 Ribosomes.
 A single chromosome. (They
have DNA!)
 A cell wall that protects the
cells from drying out.
 Some bacteria may have a
flagellum, or whip-like tail to
help them move.
How Are Bacteria
Classified?
Because bacteria do not
have a nucleus, they are
Prokaryotes.
They are divided into two
kingdoms:
Archaebacteria
Eubacteria
Archaebacteria
Archaebacteria live in extreme
conditions such as hot springs.
They generally live
in oxygen-free
environments.
Archaebacteria
Some live in The
Great Salt Lake.
Some live in
acid waters
Some live in the
stomachs of cows.
Eubacteria
Eubacteria can live in extreme
environments too.
These bacteria are found
just about everywhere.
Some are heterotrophic.
(they get their food by
absorbing it)
Eubacteria
 Some are autotrophic. (they
make their own food using
the energy of the sun)
 Some are chemosynthetic
autotrophs. (they make
their own food using the
energy of inorganic
compounds containing
sulfur and nitrogen)
Bacteria Have Different
Shapes
Bacteria generally appear as one of
three shapes: rod, round or spiral.
Coccus: round
Bacillus: rod
Spirillum: spiral
Bacterial Reproduction
 Bacteria can reproduce by
two different methods:
 Binary fission
 Conjugation
Asexual/Binary Fission
 Binary fission is a method of
asexual reproduction where :
 the chromosome makes a
copy of itself;
 each copy moves to opposite
ends of the cell;
 the cell divides, leaving each
new cell with the identical
DNA as the original cell.
Sexual/Conjugation
 Conjugation is sexual
reproduction.
 Two bacteria may exchange
genetic material, or one may
give part of its chromosome
to another bacterium across
a bridge formed between the
two cells.
 This results in two cells with
different genetic makeup.
Survival of the Fittest!
 Bacteria have an uncanny ability to survive.
 They can form endospores when conditions
are unfavorable for survival.
 An endospore is made of a tough coating, the
chromosome, and a bit of cytoplasm.
 Endospores can survive high temperatures,
dryness, freezing conditions, and harsh
chemicals.
Beneficial Bacteria
Not all bacteria are
harmful!
Many bacteria live in the
digestive systems of
animals and humans,
and aid in digestion.
(Remember: extreme
conditions!)
Beneficial Bacteria
Bacteria act as
decomposers. Dead
plants and animals are
decomposed by bacteria
and their nutrients are
returned to the air and
soil.
Bacteria: Amoeba Sisters
Beneficial Bacteria
Many bacteria convert
nitrogen from the air into
ammonia, and then into
nitrites and nitrates in the
soil which can then be used
by the roots of plants.
Fertilizer!
Other bacteria are used to
make foods, such as cheese,
yogurt, and vinegar.
Antibiotics
 Antibiotics are substances
which kill bacteria.
 Some antibiotics are produced by
certain species of bacteria for the
purpose of killing other bacteria.
 Some antibiotics are produced by
certain species of fungi in order to kill
bacteria that might grow near them.
Antibiotics vs Bacteria
•Some antibiotics work by interfering with the
cell wall of the bacterium, creating holes in the
cell wall. Cell contents leak and the bacteria
die.
•Antibiotics may not kill all of the bacteria –
some may survive and reproduce, carrying the
genes for ‘resistance.’
•Antibiotics are not effective against viruses,
because viruses are NOT alive.
Harmful Bacteria
 Pathogenic bacteria cause disease.
 The bacteria that infect the body may affect the
function of normal body tissue,
 Or they may produce a toxin that attacks the host
tissue.
© Lisa Michalek
Characteristics of Fungi
 Some members of the Kingdom Fungi, such as
molds and mushrooms, are very common and grow
so rapidly that they sometimes appear overnight.
 The first Fungi appeared on Earth about 430
million years ago.
 In the past, biologists grouped
fungi with plants because fungi
are immobile, have a cell wall
and appear “rooted” in the soil.
 However, the unique features of
fungi indicate that they should be
classified as a separate kingdom.
Characteristics of Fungi
 Fungi are Heterotrophic.
 The stalk and cap of the
mushroom are not green
like the stem and leaves of a
plant.
 Plants appear green because
they contain chlorophyll,
the pigment that aids in
photosynthesis.
 Fungi do not contain
chlorophyll.
 Fungi obtain their energy
by breaking down organic
material that they absorb
from their environment.
Characteristics of Fungi
 Fungi have Filamentous Bodies.
 Plants are made of many cell and tissue types, but
fungi are made of long, slender filaments.
 These filaments weave tightly together to form the
fungus body and reproductive structures.
Characteristics of Fungi
 Fungal Cells contain Chitin.
 The cells of all fungi have walls made of chitin.
 The tough polysaccharide found in the hard outer
covering of insects.
 Plant cells have walls made of cellulose, a different
polysaccharide.
Characteristics
of
 Fungi exhibit
Nuclear Mitosis.
Fungi
 Mitosis in fungi is different from mitosis in plants and
in most other eukaryotes.
 In most eukaryotes, the nuclear envelope disintegrates
in prophase and re-forms in telophase.
 In dividing fungi cells, the nuclear
envelope remains intact from prophase
to anaphase.
 As a result, spindle fibers form within
the nucleus.
 The spindle fibers then drag chromosomes
to opposite poles of the nucleus rather
than to opposite poles of the cell.
 Mitosis is complete when the nuclear
envelope pinches in two.
Structures of Fungi
 All fungi except yeasts have bodies composed of
slender filaments called hyphae.
 When hyphae grow, they branch and form a tangled
mass called a mycelium.
 A mycelium can
be made of
many meters
of individual
hyphae.
Structures of Fungi
 This body organization provides a high surface-areato-volume ratio, which makes a fungus well suited for
absorbing nutrients from its environment.
 Each hypha is a long string of cells divided by partial
walls.
 Some species do
not have walls
between cells.
 Cytoplasm flows
freely throughout
the hypha.
Fungi Nutrition
 All fungi obtain nutrients by secreting
digestive enzymes that break down organic
matter in their environment.
 Fungi then absorb the decomposed
molecules.
Fungi
Nutrition
 Many fungi decompose
nonliving organic matter,
such as leaves, branches,
dead animals, and waste.
 Other fungi are parasites
that absorb nutrients from
living hosts.
 Fungi often grow on human
foods, such as bread and
fruit but also are known to
attack nonfood materials
such as paper, cardboard,
cloth, paint, and leather.
Fungi Nutrition
 Some fungi are useful in baking,
brewing and wine-making.
 Others provide the flavor and
aroma of certain cheeses.
 Many kinds of antibiotics, such as
penicillin, are produced by fungi.
Penicillin G
Reproductive Structures
Three Sexually Reproducing Phyla of Fungi
Phylum
Characteristics
Examples
Zygomycota
Sexual spores are formed in
Black
zygosporangia; hyphae have no walls Bread
Molds
Ascomycota
Sexual spores are formed in asci;
hyphae are divided by walls
Morels,
Truffles,
Yeasts,
Cut fungi
Basidiomycota
Sexual spores are formed in basidia;
hyphae are divided by walls
Mushrooms,
Puffballs,
Rusts,
Smuts
Bread-Mold Sandwiches
 An Indonesian food called tempeh is made of
soybeans that are boiled, skinned, and inoculated
with various species of Rhizopus (bread mold).
 The tempeh is then fried, roasted, or diced in
preparation for a meal.
 Today, tempeh can be found
in health food and natural
food stores, as well as some
large supermarkets.
Basidiomycetes
 Mushrooms are members of this phylum
 Other Basidiomycetes include toadstools, puffballs,
jelly fungi, and shelf fungi.
 The basidium is the club-shaped sexual reproductive
structure for which this
phylum is named.
 Spores are produced
on this structure.
Basidiomycetes
 Asexual reproduction is rare,
except in some rusts and smuts.
 These two important groups of plant
pathogens affect many crop plants.
 Many mushrooms are harmless,
but many are also deadly.
 Poisonous mushrooms cannot be
discerned by a quick test such as
smearing liquid from a mushroom
on white paper and looking for a
color change or looking for a color
change in a broken stem.
 Only a trained mycologist should
attempt to identify edible
mushrooms.
Mushroom Characteristics
 Body Structure:
 The multicellular body of a fungus is basically
filamentous.
 It consists of long strings of cells called hyphae.
 Hyphae are woven
together to form
a dense mat
called a mycelium.
Mushroom Characteristics
 Nutrition:
 Fungi are heterotrophs.
 Fungi secrete enzymes that break down
organic materials into simple molecules that
the hyphae can absorb.
 Fungi store food as glycogen.
Mushroom Characteristics
 Reproduction:
 Under proper conditions, underground hyphae grow upward
and weave together to produce a mushroom.
 A mushroom has a flattened cap attached to a stem called a
stalk.
 The underside of the cap is lined with rows of gills.

Thousands of club-shaped reproductive cells called basidia
form on the gills.
 Through fusion and meiosis, each basidium produces
spores that are released and form new hyphae.
Fungal Partnerships
 Symbiotic Relationships
 Fungi are involved in many kinds of symbiotic
associations with algae and plants.
 These mutualistic relationships play important roles in
ecology.

Mutualism is a type of relationship
in which each partner benefits.
 The fungus (a heterotroph) provides
minerals and other nutrients that it
absorbs from the environment.
 The algae or plant
(a photosynthesizer) provides
the ability to use sunlight to power
the building of carbohydrates.
Fungal Partnerships - Mycorrhizae
 A type of mutualistic
relationship formed between
fungi and vascular plant roots.
 The hyphae help transfer
phosphorus and other minerals
from the soil to the roots of the
plant, while the plant supplies
carbohydrates to the fungus.
 The hyphae penetrate the outer cells of the root.
 Fossils show that the root-like structures of the earliest
plants often had mycorrhizae, which may have played an
important role in the invasion of land by plants.


Scientists think that when plants invaded the land the soil of that
time completely lacked organic matter.
Plants with mycorrhizae can grow successfully in infertile soil.
Fungal Partnerships - Mycorrhizae
 In many plants, the mycorrhizae do not physically
penetrate the plant root but instead wrap around it.
 These kinds of mycorrhizae are
important because they aid the
growth of many commercially
significant trees, such as pines,
oaks, beeches, and willows.
 Some produce economically important edible mushrooms,
and some of the ascomycete species produce
an edible fruiting body called a truffle.
Fungal Partnerships - Lichens
 A lichen is a symbiosis between a fungus and a
photosynthetic partner such as a green algae, a
cyanobacterium, or both.
 The photosynthetic partner provides carbohydrates.
 It is protected from the environment by the fungal
partner, which helps it absorb mineral nutrients.
 In most lichens, the fungus
is an ascomycete.
Fungal Partnerships - Lichens
 When you look at a lichen, you are seeing the
fungus.
 The photosynthetic partner is hidden between the
layers of hyphae.
 Sunlight penetrates
the layers of hyphae
and enables the
partner to carry out
photosynthesis.
Fungal Partnerships - Lichens
 The tough construction of the fungus combined
with the photosynthetic abilities of the algae, or
cyanobacterium, has enabled lichens to
colonize harsh habitats.
 Lichens have been
found in arid desert
regions and in the
Arctic; they grow on
bare soil, on tree
trunks, and on
sun-baked rocks.
Fungal Partnerships - Lichens
 During succession, lichens are often the first
colonists.
 They break down rocks and
prepare the environment
for other organisms.
 Lichens are a key component
of primary succession
because they are able to
grow on rock and help break the rock down into soil.
 Lichens containing cyanobacteria carry out
nitrogen fixation and introduce useful forms of
nitrogen into the soil.
Fungal Partnerships - Lichens
 Lichens are able to survive drought and freezing by
becoming dormant.
 When moisture and warmth return, lichens resume
normal activities.
 In harsh environments, lichens may grow slowly.
 Some lichens that grow in
the mountains appear to
be thousands of years old
and cover an area no larger
than a fist.
 These lichens are among
the oldest living organisms
on Earth.
Fungal Partnerships - Lichens
 Although lichens are known to survive extremes of
temperatures, they are susceptible to chemical
changes in their environment and can become a
living indicator of the amount of pollution in the
environment in which they live.
 Lichens have no roots, so the nutrients they take up must
come from the air.
 Rain, fog, and dew wet the surface of a lichen.
 When they are wet, lichens absorb nutrients and any
pollutants that are in the air.
Indicator Species
Xanthoria parietina
Xanthoria polycarpa
1 cm
1 cm
Physcia tenella
1 cm
Usnea cornuta
Hypogymnia physodes
Nitrogen-loving
Sulphur-tolerant
Indicator of
clean air
1 cm
1 cm
What Do You Know
About Viruses?
You probably know that
they cause diseases.
And you probably know
that they are so small,
you can’t see them
unless you use a high
Did you know that
resolution microscope! viruses are NOT alive?
Viruses
Viruses are hundreds
of times smaller than
bacteria.
Scientists must use an
electron microscope to
see viruses.
Viruses
 There are many
different kinds and
types of viruses.
What Do All Viruses Have
In Common?
 They do not move on their own, nor use
energy.
 They do not eat or release wastes.
 They do not carry on metabolism.
 They are made of only a protein coat and
either DNA or RNA.
Can Viruses Do ANYthing?
Viruses have one function in
common with living things:
- they can reproduce!
- but, only inside a living cell.
So, How Can They Hurt Us?
Since they have genetic material, they have the
capability of infecting living things.
Each type of virus can specifically
infect only certain kinds of cells.
A plant can be
infected with a
virus that will not
affect you.
You can be
infected with a
virus that will not
affect your dog.
Viral Specificity – The
Secret Weapon!
 The protein coat of a
The ‘knobs’ on the
outside of the virus are
protein markers, which
chemically recognize
only host cells.
virus is specific to
its host cell.
 The virus will only
attach to a cell
which it chemically
recognizes.
Viral Specificity
A virus cannot attach to a cell
membrane for which it does
not have a specific molecular
attraction.
Viruses
Viruses cannot move. They are at the
mercy of the elements.
If you are infected with a virus,
and you sneeze, you may be
transmitting the virus to others
through the moisture particles
you expel!
Tricky Viruses…
And, depending on the type of virus, the
viral particles may survive ‘intact’ for
hours on a surface before degrading.
If you touch that surface with your
hands, and then touch your eyes, nose,
or mouth, you may become infected! IF
the virus has specificity to your cells!
What Does the Virus Do Once It
Invades Your Body?
 First, a virus must attach to
a host cell and inject its
genetic material, or be
enveloped by the host cell.
 From here, the virus will
take one of two courses,
depending on the type of
virus.
Two Types of Viral
Replication
 Viruses may undergo one
of two methods of
replication inside the cell:
 Lytic cycle
 Lysogenic cycle
Viral Replication –
Lytic Cycle
 In the lytic cycle, viruses attach to the
host, take over the cell’s machinery, and
new viral particles are made right away.
 The host cell’s nucleus, ribosomes, and
other organelles are forced into
creating and assembling these new
viral particles.
Lytic Cycle
 The cell fills up with the newly-formed
viruses and cannot function.
 The cell bursts, releasing the newlyformed viruses. This may only take 30
minutes!
Lytic Cycle
 The newly-formed viruses can attach to
new host cells and repeat the process.
 Only the host’s immune system can
attack the viruses and get the infection
under control!
 Colds, flu, and measles viruses go
through a lytic cycle.
Bacterial Diseases
 Strep throat, tuberculosis, anthrax,
Lyme disease, tooth cavities, cholera
and tetanus are examples of diseases
caused by bacteria.
Bacterial Diseases
 Cholera is caused by drinking
unclean water that contains the
cholera bacteria.
 Tetanus can be contracted when the tetanus
bacteria, found in the soil, get into your body
through a puncture wound.
 Lyme disease can be contracted after being
bitten by the blacklegged tick.
Viral Replication –
Lysogenic Cycle
In the lysogenic cycle, viruses
attach to the host, but mix
their genetic material with the
host’s, and do not cause new
viral particles to be made right
away.
Lysogenic Cycle
 Later, something may trigger
new viruses to be made and
then the lytic cycle begins.
 Lysogenic cycles may be
months to years long!
Lysogenic Cycle
HIV/AIDS, shingles, cold sores, and
warts are examples of diseases caused
by viruses that go through the
lysogenic cycle.
HIV/AIDS
The HIV/AIDS virus attacks the immune
system. It may lie dormant for years
before it enters the lytic cycle.
The HIV virus may be
spread by sharing
needles, or
exchange of body
fluids such as blood.
Defense Against Disease
 Wash hands thoroughly with soap and water,
often.
 Cover your mouth with a tissue or your sleeve
when coughing or sneezing.
 Get vaccinated against common viral diseases.
Defense Against Disease
 Stay away from others who may have a viral
infection.
 Do not share food dishes and drinking glasses
with others who are sick.
 Stay home when sick – do not pass around your
illness.
Bacteria and Viruses.
1. Bacteria contain a
membrane-bound
nucleus.
2. Many bacteria are helpful in
digestion.
3. Bacteria are used in the
manufacture of yogurt, cheeses,
and vinegar.
4. Prokaryotic cells have _____
mitochondria
organelles
a nucleus
a cell wall
chloroplasts
Answer:
D – Prokaryotic cells have a cell
wall.
They do not have any membranebound organelles.
5. Antibiotics kill all bacteria
every time.
6. Many diseases caused by
bacteria actually make you sick
because of the toxins they
produce.
7. Which of the following spreads
disease-causing bacteria?
Access to new hosts
Low temperatures
Mutation by heat energy
Availability
Exposure to sunlight
Answer:
 A – Access to new hosts spreads
disease.
 Low temperatures keep bacteria from
growing rapidly, and exposure to
sunlight usually kills bacteria.
8. Viruses contain a nucleus
and a cell wall.
9. What characteristic do viruses
share with all living organisms?
movement
respiration
reproduction
metabolism
growth
Answer
 C – Reproduction. Viruses can replicate
only inside a living cell.
 Viruses do not carry on respiration,
movement, metabolism, or growth.
10. HIV, the virus that causes
AIDs, can hide inside a cell for
years, then become active and
start killing cells.
11. Polio, measles,
mumps, and the flu are all
caused by viruses.
12. Streptococcus, anthrax, and
cholera are caused by viruses.
13. Many viral diseases can be
prevented by vaccines.
14. Some bacteria can take
nitrogen from the air and convert
it into fertilizer for plants.
15. Bacteria act as
decomposers.
16. Viruses have external
protein markers which allow
them to recognize a specific
host cell and infect it.
17. Once a virus enters a cell, it can
cause the host cell to immediately
make new viruses. This is called
an invasion
the lysogenic cycle
a mutation
the lytic cycle
AIDS
Answer:
 D – The lytic cycle is the immediate take-
over of the cell by the virus.
 The lysogenic cycle is when the virus is
incorporated into the host’s DNA and does
not immediately kill the host cell.
18. The human immunodeficiency
virus attacks a person’s
respiratory system
first.
19. Some bacteria have flagella.
These structures are used for
making protein
digestion
replication
attaching to surfaces
locomotion
Answer:
 E – Flagella are used for locomotion.
20. Antibiotics are used to kill
viruses.
21. Pathogenic bacteria are
disease-causing bacteria.
22. Which of the following is a way
that HIV can be transmitted?
Shaking hands
Hugging a person
Sharing needles
Infected toilet seats
Sharing food
Answer:
 C – Sharing needles is a way to transmit
HIV.
23. Cholera is a bacterial
disease transmitted by
contaminated water.
24. Tooth cavities are caused by
acids released by bacteria in the
mouth.