Unit 3: Microscopes, cells and Viruses pp. 191-200 Modern - - PowerPoint PPT Presentation

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 ________________, _________________

• r ____________.

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.

proteins shape 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

• r 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

• rganelles

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
• rganelles located on

_________________

• r 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
• f ________________. 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 _______, _________, _________________,

• r wastes. Plants

have a large central vacuole.

water Salts, proteins carbohydrates

Mitochondria

• Double-walled
• rganelle 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

• wn ______.

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

• rganelles

structure cilia 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 Membrane

Every 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