Viruses, Bacteria, Protists, Fungi
Chapter 7
Grade 7 Science
Viruses
• _____
Virus - a tiny, non-living particle invades and
then multiplies inside of a living cell.
• Viruses can only multiply when they are _____
inside of
a living cell.
• ______
- a living thing that provides the energy
host
source for a virus.
• ________
- organisms that live on or in a host and
parasite
can cause it harm.
• Viruses act like parasites but they are not
___________.
organisms
Structure of Viruses
• Viruses have three distinct shapes:
round
– _________
– _______
rods
– ________
threads
All viruses have two basic parts:
Protein coat that protects the virus
1. A __________
Inner core
2. A ___________
made of genetic material
Virus Structure and Host Cells
keys
locks
• Viruses are like ______
that fit into ______
which is a protein on the surface of a host cell.
Lock and Key action - the shape of surface
• ______________
proteins allows the proteins to fit into a only
certain proteins that are located on the
surface of the host.
bacteriophage
• ______________
- a virus that infects bacteria
and has a robot-like shape.
How Viruses Multiply
• After a _________
attaches to a ________
it
virus
Host cell
enters the cell.
• After the virus enters the cell, the
____________
genetic material takes over many of the cell’s
functions.
• The ___________
genetic material instructs the cell to produce
the virus’s proteins and genetic material.
• The ________
and ___________
proteins
genetic material continue to
multiply into new viruses
Active Viruses
Active Viruses
• ___________
- enter cells and immediately
begin to multiply leading to the quick death of
the invaded cells.
• _____________
- “hide” for a while before
Hidden Virus
becoming active inside of the host cell. The
hidden virus hides inside of the host cells
___________
Genetic material before it becomes active.
Viruses and Diseases
Viruses
diseases
• ________
cause ________
• Viral diseases are spread through ________,
contact
Drops of moisture
_________,
_____________,
and
bites
___________.
Body fluids
• _________
- a substance introduced into the
Vaccine
body to stimulate the production of chemicals
that destroy specific disease causing viruses
and organisms – a ___________
measure.
preventative
Bacteria
Anton van Leeuwenhoek - discovered bacteria in
• ________________
the late 1600’s.
• __________
- single celled organisms with no
bacteria
nucleus.
• __________
- the genetic material is not
prokaryotes
contained in the nucleus.
Cell wall
Cell membrane
• Bacteria cells have _______
and __________
Bacteria – Structure
Bacteria - Size
Obtaining Food and Energy
• Bacteria must have :
1. _____________
Source of food
2. ______________
Energy supply
Some Bacteria are __________
autotrophs - self feeders
Bacteria make their food in 2 ways:
Suns energy
1. ______________
2. _______________________________________
Energy from chemical substances in the environment
heterotrophs - other feeders that feed
Some bacteria are __________
on other organisms or the food that other organisms
make.
Respiration
energy
• _________
comes from breaking down food in
the process of __________.
respiration
oxygen
• Some bacteria need ________
for respiration
oxygen
• Others do not need ________
- these bacteria
are called __________
and will die in the
anaerobic
presence of oxygen.
Reproduction
• Bacteria need the following for reproduction:
1. ___________
food
temperature
2. ___________
Suitable conditions
3. _______________
Asexual
Reproduction - reproductive process that
________________
requires only one parent.
- ___________
Binary fission - one cell divides to form two
identical cells – each cell gets its own complete
copy of the parents cell’s genetic material,
ribosomes and cytoplasm
Reproduction Continued
• ______________
Sexual reproduction - two parents combine their
genetic material to produce a new organisms.
conjugation - one bacterium transfers some
– _________
genetic material to another and then the cells
separate.
– Bacteria can survive harsh conditions by forming
endospores - a small, round, thick-walled, resting
__________
cell that forms inside a bacterial cell.
freezing
heating and
- endospores can resist _________,
_______,
drying - they can survive for many years
______
Bacteria in Nature
• Bacteria are involved in:
Oxygen and food production
– ______________________
– ___________________________
Environmental recycling and cleanup
Health maintenance
– _________________
Medicine Production
– _________________
Autotrophic bacteria were
Scientists believe that _________________
responsible for adding oxygen to the Earth’s
atmosphere.
Bacteria keep oxygen levels in the air ________.
stable
Food Production / Environmental
Recycling
Pasteurization named after Louis Pasteur, is a
• __________process where beverages such as milk and
juices are heated to a temperature high
enough to kill harmful bacteria without
destroying the taste.
Decomposers
• ___________
- are “nature’s recyclers” –
return basic chemicals such as nitrogen
______ to the
environment for other living things to use.
Recycling and Nitrogen-Fixing
Decomposing bacteria
• ________________
break down chemicals in
leaves and branches that drop to the ground.
Once these materials are broken down, they
mix with soil and can be absorbed from
_______
of nearby plants.
roots
• ________________
Nitrogen-fixing bacteria live in soils and convert
nitrogen gas from the air to nitrogen products
that plants need to grow.
Health and Medicine
Help to digest food
• Bacteria _______________
• Bacteria ____________
Make vitamins
• Good bacteria can help harmful bacteria from
making your sick.
• ________________
Insulin-making bacteria - purified and made into
medicine for people that cannot make their
own.
Protists
Protists
• ___________
- eukaryotes that cannot be
classifies as animals, plants, or fungi
• All protists live in _____
moist surroundings.
• Animal-like protists - protozoans
________ are
heterotrophs - other feeders.
__________
unicellular
• Protozoans are __________
- one celled
• Protozoans are classified into 4 groups based
move
live
on the way they ________
and ________
Protozoans with Pseudopods
• ________
- sarcodines that live in either water
amoeba
or soil.
Sarcodines
• __________
- move and feed by forming
pseudopods.
False foot
• Pseudopod means “__________”
– temporary
bulges in the cell
cytoplasm flows in
• Pseuodopds move when the _______
one direction and the rest of the organism
follows
Pseudopds
• Sarcodines use pseudopds to __________.
Trap food
• The pseudopds are extended on both sides of
the food particle until the pseudopods join
together and the particle is trapped.
Contractile vacuole
• _______________
- a structure that collects
extra water that is taken into the cells of
protozoans that live in fresh water such as
amoeba - the water is then expelled so that
_______
the amoeba will not burst.
Protozoans with Cilia
cilia - hair like projections from cells that
• ____
move in a wavelike motion.
ciliates
• _______
use cilia to _____
move and obtain _____.
food
paramecium - ciliates that are complex – two
• __________
_____________
Contractile vacuoles and more than one _______
nucleus
asexually
• Paramecium reproduce __________
by
___________or
___________
Binary fission
conjugation
Protozoans with Flagella
• Protists that use long, whip-like structures to
move - _______
flagella
• Some protozoans
_________ live inside of the bodies of
other organisms.
• The relationship where one organism is helped is
called ________.
(ex. Flagellate that lives inside
symbiosis
of the intestine of termites)
• The relationship where both organisms are
mutualism - a type of
benefited is called ________
symbiosis
_________
Protozoans that are Parasites
Plantlike Protists
•
•
•
•
algae
Plantlike protists are called _____.
Algea are __________.
autotrophs
Algea are _________
Food sources and / or ____________
Oxygen producers
colonies are groups of unicellular organisms
_______
that live together – some cells in the colony
are specialized for certain functions such as
____________
reproduction
multicellular
• Some algea are also __________
Diatoms
Diatoms
________
are unicellular protists with glasslike
cell walls.
Food source for
Diatoms are a _________
___________organisms
in waters – diatoms
heterotrophic
either float or attach to objects in shallow
waters.
Diatoms move by oozing chemicals from their
cell walls and then gliding in the slime.
Dinoflagellates
dinoflagellates
• _____________
- unicellular algea surrounded
by stiff plates
• Dinoflagellates have two _______
that are
flagella
held in between their plates.
• Dinoflagellates whirl through the water with
their flagella and some are ______________.
Glow in the dark
ocean
• Found on the surface of _______
waters
Euglenoids
• ________
Euglenoids are green unicellular algea that are
found in fresh water.
• Euglenoids have one animal-like characteristic
heterotrophic
– they can be ___________
when sunlight is
not available.
• ________a common euglenoid that has a
euglena
long whip-like flagellum that helps it to move..
• _______
- helps the euglena to find light
eyespot
sources – valuable for autotrophs.
Red Algae
multicellular
• Almost all red algae are __________
• Red _________
absorbs small amounts of light
pigment
that is able to reach deep below the oceans
surface.
• Red algae is used by humans in products such
as _________,
_________,
and other nutrient
Ice cream
conditioner
rich foods in Asia.
Green Algae
• Green algae contain ____________
and are
Green pigment
very diverse.
• Green algae can be _________,
form
unicellular
colonies
_________,
or be multicellular.
Fresh water
Salt water
• Live in either ____________
or __________.
• Green algae and plants share the same type of
chlorophyll
___________
• There is a debate over whether green algae
belongs in the ______
kingdom.
plant
Brown Algae
• ____________
are brown algae.
Sea weeds
• Brown algae contain ________,
________,
brown
green
orange
_________,
and _______
pigments.
yellow
• Cool, rocky waters
• Brown algae can form underwater _____
forests and
provide valuable habitat for underwater
creatures.
• Some humans eat brown algae and use it in
products such as thickeners in foods.
Fungi-like Protists
• Third group of protists (animal-like and plant-like
protists)
heterotrophs __________,
have cell walls
• Fungus-like protists are _________,
and _________________.
Use spores to reproduce
• Three types of fungus-like protists include:
• _________
Slime molds - forest floors, moist shady places
• __________
Water molds - decomposers of dead aquatic
organisms, parasites of fish and other animals
• ___________
Downy mildews - parasites of many food crops
Fungi
• Characteristics of fungi:
eukaryotes - organism whose cell contains a
– _________
nucleii
– ____________
heterotrophs - other feeder
Absorb their food
– _____________
– ________________
Reproduce by spores
– _________________________
Need moist , warm places to grow
Cell structure
unicellular
multicellular
Fungi can be either _________
or ___________
The cells of all fungi are surrounded by a
_______
Cell wall
hyphae All fungi, except for yeast, have _____
branching thread-like tubes
Hyphae are useful in the process of
____________
Food absorption
Obtaining Food
hyphae
• First the fungi grow the _______
into the food
source – ex. Fungi on dead trees
• Next, the hyphae release a chemical into the
food source to help break the food down
absorb the food that has
• Then the hyphae ______
been broken down by the digestive chemicals
that were released
Reproduction
• Fungi reproduce by _____
spores - asexual and sexual
• Fungi make spores _______
asexually - cells at the tips
of the _______reproduce
to form _______
hyphae
spores
• Yeast is an exception – yeast cells reproduce
budding - similar to a bud growing on
through _______
a tree branch – no spores are formed.
Sexual reproduction - the hyphae of two fungi
• _____________
grow together and the genetic material is
exchanged.
Role of Fungi in Nature
•
•
•
•
Foods for people
1. _____________
2. _________________
Environmental Recycling - decomposers
Disease fighting fungi - penicillan
3.________________
Disease Causing Fungus - parasites on plants,
4. _______________
Dutch elm disease, corn smut, wheat rust,
athlete’s foot, ringworm
• ______
Lichens - fungal and bacterial relationship –
“pioneer” organisms.
Lichens