Chapter 20Chapter 20

• Viruses Viruses

andand

BacteriaBacteria

MeasurementMeasurementMicroorganisms: very small Microorganisms: very small

Use metric system Use metric system Meter (m): standard unit Meter (m): standard unit

Micrometer (mm) = 0.000001 Micrometer (mm) = 0.000001 meter or meter or

1 X 10-6 meter 1 X 10-6 meter Nanometer (nm) = Nanometer (nm) =

0.000000001 meter or 1 X 10-9 0.000000001 meter or 1 X 10-9 metermeter

Viewing BacteriaViewing Bacteria

• Preparation of Preparation of Smears for Smears for StainingStaining

• Bacteria are Bacteria are colorless when colorless when viewed under viewed under light microscope light microscope

• Fix or attach Fix or attach bacteria to slide. bacteria to slide.

bacteriabacteria

StainsStains• Stain: salts composed of a Stain: salts composed of a

positive and negative ion. One of positive and negative ion. One of which is colored chromophore. which is colored chromophore. – Basic dyes: the color is a positive ion. Basic dyes: the color is a positive ion. – Acidic dyes: the color is a negative ion.Acidic dyes: the color is a negative ion.

Gram StainGram Stain

• Gram stain Gram stain – crystal violet: primary stain crystal violet: primary stain – iodine: mordant iodine: mordant – alcohol or acetone-alcohol: decolorizer alcohol or acetone-alcohol: decolorizer – safranin: counterstain safranin: counterstain

• Gram positive: purple Gram positive: purple

• Gram negative: lose purple. Stain Gram negative: lose purple. Stain pink-red.pink-red.

ProkaryotesProkaryotes

•Why are prokaryotic cells Why are prokaryotic cells classified in a different classified in a different Kingdom from the eukaryotic Kingdom from the eukaryotic cells?cells?

No NucleusNo Nucleus

•DNA is not in a DNA is not in a membrane; is a circular membrane; is a circular chromosome. chromosome.

NO Organelles NO Organelles

•Lack other Lack other membrane-membrane-enclosed enclosed organelles. organelles.

No chromosomes No chromosomes

•DNA is not associated with DNA is not associated with histone proteins. histone proteins.

ReproductionReproduction

•Prokaryotes Divide by Prokaryotes Divide by binary fissionbinary fission

ShapesShapes• Shapes of Shapes of

ProcaryotesProcaryotes• Cocci: round Cocci: round

– diplococci diplococci – streptococci streptococci – tetrads-groups of 4 tetrads-groups of 4

• Rods: coccobacilli Rods: coccobacilli • Spiral: vibrios, Spiral: vibrios,

spirilla, spirochetes spirilla, spirochetes • Star-shaped, square Star-shaped, square

flat cells, triangularflat cells, triangular

Gram Negative Cell WallGram Negative Cell Wall• pinkpink

Gram Positive Cell WallGram Positive Cell Wall

• purplpurplee

• A. The Bacteria that we generally A. The Bacteria that we generally refer to as "GERMS" are classified in refer to as "GERMS" are classified in the the KINGDOM EUBACTERIA, or KINGDOM EUBACTERIA, or EUBACTERIA, or simpler yet EUBACTERIA, or simpler yet BACTERIA.BACTERIA.

•         B. The Other Type of bacteria are B. The Other Type of bacteria are called called ARCHAEBACTERIAARCHAEBACTERIA, and , and belong to the belong to the KINGDOM KINGDOM ARCHAEBACTERIAARCHAEBACTERIA.  These are the .  These are the more ancient bacteria.more ancient bacteria.

KINGDOM KINGDOM ARCHAEBACTERIAARCHAEBACTERIA

• The PREFIX "The PREFIX "ARCHEAARCHEA" means " means ANCIENTANCIENT.  They are considered .  They are considered ancient because they probably ancient because they probably resemble the FIRST FORMS of LIFE on resemble the FIRST FORMS of LIFE on Earth. Earth.

METHANOGENS

THERMOACIDOPHILES

EXTREME HALOPHILES

KINGDOM EUBACTERIAKINGDOM EUBACTERIA

• PREFIX "PREFIX "EUEU" means " means TRUETRUE

EubacteriaEubacteria

• classified by: classified by:

Shape: •Cocci - round bacterial cells.      •Bacilli - rod-shaped bacterial cells.      •Spirilli - spiral-shaped bacterial cells.

Clustering: Clustering:

• staphylostaphylo - a prefix used with the - a prefix used with the shape name to indicate clusters. shape name to indicate clusters. streptostrepto - a prefix used with the - a prefix used with the shape name to indicate filamentsshape name to indicate filaments

VIRUSVIRUS

Herpes VirusHerpes Virus

•Herpes viruses are Herpes viruses are extremely common and extremely common and around 100 have been around 100 have been identified in a variety of identified in a variety of animal species.  animal species.  

HerpesHerpes

•All of the herpes viruses are All of the herpes viruses are members of one family, the members of one family, the Herpesviridae, and have Herpesviridae, and have certain characteristics in certain characteristics in common, such as their ability common, such as their ability to establish latency during to establish latency during primaryprimary

Why does it come Why does it come back?back?

• Following initial infection the Following initial infection the virus remains dormant, to be virus remains dormant, to be reactivated by certain triggers reactivated by certain triggers such as an individual’s immune such as an individual’s immune status, stress or sunlight.status, stress or sunlight.

Herpes VirusesHerpes Viruses

•To date, eight human herpes To date, eight human herpes viruses have been identified. viruses have been identified.

•These include: These include:

Herpes groupsHerpes groups

• Epstein-Barr virus, which causes infectious Epstein-Barr virus, which causes infectious mononucleosis (also known as ‘mono’ and mononucleosis (also known as ‘mono’ and ‘glandular fever’);‘glandular fever’);

• Varicella zoster, which causes chickenpox Varicella zoster, which causes chickenpox and shinglesand shingles

• Herpes simplex virus type 1, the cause of Herpes simplex virus type 1, the cause of cold sores;cold sores;

• infectious mononucleosis.infectious mononucleosis.• Herpes simplex virus type 2, the most Herpes simplex virus type 2, the most

common cause of genital herpes.common cause of genital herpes.

““Cold Sores” Cold Sores”

• Herpes Herpes simplex simplex virus type 1, virus type 1, the cause of the cause of cold sores; cold sores;

• • Typical Typical

blisters blisters associated associated with cold with cold sores due to sores due to HSVHSV

Chicken PoxChicken Pox

• Varicella zoster, Varicella zoster, which causes which causes chickenpox and chickenpox and shingles;shingles;

•

• Typical rash of Typical rash of chickenpox in an chickenpox in an adolescent.adolescent.

Lyme diseaseLyme disease

Caused by a spiral Caused by a spiral bacteriumbacterium

A tick embedded in the skinA tick embedded in the skin

AnthraxAnthrax• Anthrax is a bacterial infection Anthrax is a bacterial infection

caused by spores from the bacterium caused by spores from the bacterium that is shaped like a rod: bacillus that is shaped like a rod: bacillus anthracisanthracis

anthraxanthrax

Anthrax in the lungsAnthrax in the lungs

Ebola VirusEbola Virus

Mononucleosis ViralMononucleosis Viral

Symptoms of MonoSymptoms of Mono

Are viruses alive?Are viruses alive?

• What do you think? What do you think?

• They contain a protein coat and some They contain a protein coat and some genetic material either DNA or RNA genetic material either DNA or RNA

• They use living cells to reproduce They use living cells to reproduce themselves.themselves.