Unit 3: Microscopes, cells

and Viruses

pp. 191-200

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

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

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

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

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

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

• 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

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

• 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

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

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

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

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

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

• 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

Eukaryotic cell structures

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

Nucleus

• _____________ of

the cell. Genetic

information stored as

____________, which

is _______wrapped in

________________.

Control center

chromatin

DNA

protein

Found in Both Plants & Animals

Nucleolus

• Small, dense region

in the nucleus. Site of

________________

production

ribosome

Found in Both Plants & Animals

Nuclear Envelope

• Double

_________________

membrane. Has

nuclear ___________

which allow _______

to leave the nucleus

phospholipid

pores

RNA

Found in Both Plants & Animals

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

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

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

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

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

Vacuole

• Sacs that may be

used as storage for

_______, _________,

_________________,

or wastes. Plants

have a large central

vacuole.

water Salts, proteins

carbohydrates

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

Chloroplast

• Found in ______

cells. Contain

__________ (green

pigment) and their

own ______.

Chloroplasts harvest

energy from the ____

to produce ____

through __________.

plant

chlorophyll

DNA

sun

ATP

photosynthesis

Centrioles

• Found in _________

cells only. Bundles of

_________________

that play a role in

_________________

animal

microtubules

cell division

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

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

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