unit 3: microscopes, cells and viruses · scanning tunneling electron microscope (stm)-involves...
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Unit 3: Microscopes, cells
and Viruses
pp. 191-200
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Modern Microscopes
Compound light microscope
– Contain more than one
______ and uses _________
bent through _________ to
magnify objects. Type of
microscope used in the
classroom, ours magnifies up
to 430 times, others can
magnify up to a 1000 times
lens light rays
glass
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Electron microscope –
Uses magnets to aim a
beam of ________ at thin
slices of cells. . Offers the
advantage of much greater
____________. There are
4 types of electron
microscopes:
scanning electron
microscope or SEM -
traces the ___________ of
the specimen and forms a
3D image
electrons
magnification
surface
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transmission electron
microscope or TEM - aims
electron beam through
specimen. Used to examine
____________cell
structures. Can magnify up
to 500,000X
Disadvantages of these two:
specimen must be kept in a
____________; therefore
must be
____________________
internal
vacuum
dead
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scanning tunneling electron microscope
(STM)- involves bringing the charged tip of a
probe extremely close to the specimen so that
the electrons “tunnel” through gaps between
the specimen & the tip. Can create 3D
computer images of objects as small as atoms
& can be used on living specimens.
• atomic force microscope (AFM)- measures
various forces between the tip of a probe and
the cell surface. Creates a visual image of a cell
using a microscopic sensor that scans the cell
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What about Viruses? Are They Alive?
Based on what we learned in Unit 1, viruses would
be considered non-living because they do not
exhibit all the characteristics of life:
• Do not contain____________ for ____________
• Not made of ________; lack a ______________
• Do contain______________________________
• Cannot _____________ without a ________ cell
• Typically referred to as a ______________ or
__________
enzymes metabolism
cells Cell membrane
Genetic material
reproduce host
particle
virion
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Structures of Viruses
The following structures are found in all
viruses:
• Genetic material- The genome of a virus
may be either ____ or ____, but never both.
It can be ____________ or
________________, _________________
or ____________.
DNA RNA
Single-stranded
Double-stranded circular
linear
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• Protein coat- The DNA or RNA is
surrounded by a protein coat called a
capsid. The proteins making up the
capsid are known as ___________ and
play an important role in the
_____________ of the virus. In addition,
the capsid has ___________ ID tags
known as _______________ which can
__________ to enable the virus to escape
detection by a host cell’s immune system.
capsomeres
pathogenicity
carbohydrate
glycoprotein
mutate
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The following additional structures may be
present:
•Viral envelope- Many viruses have an outer
membrane known as an envelope. A viral particle
“steals” the components for its envelope from the
host cell membrane, so a viral envelope is
primarily composed of _________________. It
aids in the attachment of the virus to the host
cell, but a virus enclosed by an envelope is also
more sensitive to ______________.
phospholipids
drying
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• Tail Fibers- Viruses that infect _________
are known as ____________. They have
“tail fibers” to aid in attachment.
• Examples of viruses with envelopes are:
_________________________________
bacteria
bacteriophages
HIV, flu virus, cold virus
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The ____________ of surface _______________ on a virus fits
perfectly with the proteins embedded in the host _______
________________. As a result, a virus can only infect certain cell
types of certain species.
proteinsshape
cell
membrane
Phospholipid
envelope
Viral
DNA or
RNA
Protein
capsid
Surface protein or
glycoprotein
Naked
Capsid Virus
Enveloped
Virus
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Viral Reproduction
Two ways viruses reproduce using a host cell
• Lytic infection- _____________ cycle in
which viruses ____________ host cell DNA.
Examples are _________________________
___________
• Lysogenic infection - _____________ cycle
in which viral DNA is incorporated into
________________. Examples are
__________________
symptomatic
destroys
Cold, flu, rabies, measles, etc… most
viruses
asymptomatic
Host cell DNA
HIV, chicken pox virus
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Viral Reproduction
There are two initial steps that are common
to all types of viral infections:
1.Virus attaches to _____________ of
_____________.
2.Virus releases____________ into cell,
either by _______________ typically
through ____________ or ___________
genetic material into it.
Cell membrane
host
Genetic material
Entering cell
endocytosis injecting
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Bacteria
Bacterial make up two kingdoms, the
____________ and ____________. In this
unit, we will focus on the kingdom that has
the greater impact on our lives, the
________.
• _______________&_________________
Archaebacteria Eubacteria
Eubacteria
prokaryotic unicellular
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Cell Structures
• Cell wall composed of ________________
– __________________________
• ____________________
– ________________________
– Found in region known as ___________
• ____________________
• ____________________
• ____________________
peptidoglycan
Eubacteria only
DNA
Single, circular chromosome
nucleoid
Cell membrane
ribosomes
Cytosol — “cell gel” or fluid
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• Most bacteria are motile and have one or
more ______________.
• Many have hair-like appendages called
_________ that allow bacteria to
________ to surfaces or other _________
• Some bacteria have an outer _________;
helps bacterial cells attach to a substrate
or deter the host’s infection-fighting cells.
flagella
fimbriae
adhere bacteria
capsule
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Eukaryotic cell structures
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What’s inside a cell?
Cell organelles which means “little organs”
1st a little clarification of a couple of terms:
_______________- includes the
___________ or “cell gel” and the ________
cytoplasm
cytosol organelles
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Nucleus
• _____________ of
the cell. Genetic
information stored as
____________, which
is _______wrapped in
________________.
Control center
chromatin
DNA
protein
Found in Both Plants & Animals
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Nucleolus
• Small, dense region
in the nucleus. Site of
________________
production
ribosome
Found in Both Plants & Animals
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Nuclear Envelope
• Double
_________________
membrane. Has
nuclear ___________
which allow _______
to leave the nucleus
phospholipid
pores
RNA
Found in Both Plants & Animals
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Ribosomes
• Tiny, granular
organelles located on
_________________
or suspended in
_________. Site of
_________________.
All cells (pro & euk)
have ribosomes.
Endoplasmic Reticulum
cytosol
protein production
Found in Both Plants & Animals
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Rough Endoplasmic Reticulum
• Extensive network continuous
with _________________.
Called “rough” because it has
________________ all along
the membrane. Function of the
rough ER is to
_____________________.
Most of these proteins are
packaged into _____________
(like bubbles or sacs) and
shuttled to the ____________
nuclear envelope
ribosomes
modify & transport proteins
vesicles
Golgi apparatus
Found in Both Plants & Animals
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Smooth Endoplasmic Reticulum
• Similar to rough ER in structure, except that it lacks ___________. The smooth ER:
1. manufactures ______, 2. breaks down _______,
3. detoxifies ________, and 4. _____________.
ribosomes
lipidsglycogen
poisons
stores calcium
Found in Both Plants & Animals
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Golgi Apparatus• Flattened, round sacs that look like a sack
of ________________. Receives, modifies,
and ships products by way of ___________
into the ____________________________
pancakes
vesicles
cytosol → cell membrane_
Found in Both Plants & Animals
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Lysosome
• Found in __________
cells only. Round sacs
containing __________
that _______________
and ______________
used cell components.
Also used as defense
against _______ and
_______________
animal
enzymes
break down
recycle
bacteria
viruses
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Vacuole
• Sacs that may be
used as storage for
_______, _________,
_________________,
or wastes. Plants
have a large central
vacuole.
water Salts, proteins
carbohydrates
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Mitochondria
• Double-walled
organelle with inner
folds ____________.
____________Uses
_______ to
manufacture energy
in the form of ______.
Mitochondria have
their own _______.
to increase
surface area
glucose
ATP
DNA
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Chloroplast
• Found in ______
cells. Contain
__________ (green
pigment) and their
own ______.
Chloroplasts harvest
energy from the ____
to produce ____
through __________.
plant
chlorophyll
DNA
sun
ATP
photosynthesis
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Centrioles
• Found in _________
cells only. Bundles of
_________________
that play a role in
_________________
animal
microtubules
cell division
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Cytoskeleton• Composed of protein fibers known as _______________
and ______________. Anchor _______________ and
provide ______________. Also provide motility for some
cells in the form of ___________ or ____________. More
extensive cytoskeleton found in __________ cells.
microtubules
microfilaments organelles
structurecilia flagella
animal
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Cell walls are the outermost boundary in __________, _______, and ___________.
They are not found in _____________________. The primary function of the cell wall is to provide ___________________________. The cell wall does not regulate what _________________________ the cell.
1. Cell walls of plants are composed of ____________
2. Cell walls of fungi are composed of _____________
Cell Wall
bacteria fungi plants
Animal cells
Structure and support
Enters and leaves
cellulose
chitin
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Cell MembraneEvery cell is surrounded by a cell membrane made of
___________________. The cell membrane is
selectively permeable which means
____________________________________________.
This characteristic is critical in helping the cell maintain
_______________. The cell membrane is also called
the ____________________ membrane
Phospholipid bilayer
It only allows certain substances in and certain out.
homeostasis
Plasma