You Make Me Sick!

Bacteria and Viruses

Bacteria Bacteria

Oldest living organisms Microscopic prokaryotes

Bacteria=prokaryotes,prokaryotes=bacteria

Previously called Kingdom Monera

2 New Domains for Bacteria Archaea and Eubacteria

Overview Cell StructureOverview Cell StructureStructure Function

Cell Wall Protects and gives shape

Outer Membrane

Protects against antibodies (Gram Neg. Only)

Cell Membrane

Regulates movement of materials, contains enzymes important to cellular respiration

Cytoplasm Contains DNA, ribosomes, essential compounds

Chromosome Carries genetic information

Plasmid Contains some genes obtained through recomb.

Capsule & Slime Layer

Protects the cell and assist in attaching cell to other surfaces

Endospore Protects cell against harsh environments

Pilus Assists the cell in attaching to other surfaces

Flagellum Moves the cell

ArchaeaArchaea

Live in extreme conditions Most similar to eukaryotes

Types of ArchaeaTypes of Archaea

Methanogens: Harvest energy by converting H2 and CO2 into methane gas Anaerobic, live in intestinal tracts

Extreme halophiles: Salt loving, live in Great Salt Lake, and Dead sea.

Thermoacidophiles: Live in acid environments and high temps. Hot Springs, volcanic vents

EubacteriaEubacteria

Found everywhere else Most common Commonly called germs

Classification of BacteriaClassification of Bacteria

Shape Bacillus-rod shaped Coccus- sphere shaped Spirillum-spirial shaped

Classification of BacteriaClassification of Bacteria

Obtaining Energy & Nutrients Photoautotrophs-use photosynthesis

Major component of plankton Produce large % of oxygen Ex:cynanobacteria

Chemoautotrophs- inorganic materials Use sulfur, nitrogen, or simple organic

compounds

Classification of BacteriaClassification of Bacteria

Obtaining Energy and Nutrients(con’t) Heterotrophs (most prokarytoes)

Dead organisms,parasites, or pathogens

Classification of BacteriaClassification of Bacteria

Gram Stain Produced by peptidoglycan in cell

wall Gram-positive retain stain and

appear purple Have thicker layer in cell wall.

Gram-negative do not retain stain and appear pink stain instead.

Gram StainingGram Staining

ReproductionReproduction

Binary Fission Asexual reproduction 1 cell divides into 2 cells Usually identical Genetic mutations produce new

forms of bacteria Plamids-extra loops of DNA

Binary FissionBinary Fission

Step 1: DNA is copied and Cell grows

Binary FissionBinary Fission

Step 2:Cytoplasm and Cell Divide

Genetic RecombinationGenetic Recombination

Allows bacteria to obtain new genetic material

1. Conjugation-bacteria exchange genetic material

2. Transformation-receive DNA from the environment

3. Transduction-DNA transferred by a virus

Genetic RecombinationGenetic RecombinationCharacteristic Transformation Conjugation Transduction

Method of DNA Transfer

Across cell wall and cell membrane of recepient

Through a conjugation bridge between two cells

By a virus

Plasmid transfer

Yes Yes Not likely

Chromosome transfer

No Sometimes No

Antibiotic resistance acquired

Yes Yes Sometimes

ConjugationConjugation

TransformationTransformation

TransductionTransduction

SurvivalSurvival

Endospores Produced under harsh conditions Forms inside bacteria Resistant to radiation,extreme

temperature, lack of oxygen,etc

Bacterial DiseasesBacterial Diseases

Bacteria cause disease by… Producing toxins

Toxin-poisonous chemical Released or stored in bacteria Ex:Colstridium botulinum

Destroying body tissues Enzymes break down host tissues Ex: Tuberculosis, and Sreptococcus

Treatment- antibiotics

Bacterial DiseasesBacterial Diseases

Antibiotic Resistance

Bacteria’s ability to tolerate anitbiotics Antibiotic-inhibit the growth or kill

bacteria

Plasmids usually transmit genes for antibiotic resistance.

Caused by over use of antibiotics

Viruses

VirusesViruses

Viruses are not alive because…..

1.Not made of cells

2.Do not grow

3. Do not maintain homeostasis

4.Do not reproduce on their own

But they do have a major impact on the living world

Structure of VirusesStructure of Viruses

All viruses have a: nucleic acid Capsid

Optional Structures Envelope Tail fibers

Viral Nucleic AcidsViral Nucleic Acids

DNA Virus Contain DNA

only Ex:herpes virus

RNA Virus Contain RNA

only Retroviruses turn

RNA to DNA,then replicate

Ex:HIV

Capsid & EnvelopeCapsid & Envelope

Capsid Made of protein Encloses genetic

material Proteins match the

host cells Come in a variety

of shapes

Envelope Membrane

surrounding capsid

Made of proteins, lipids,and glycoproteins

Receptors help virus enter cell

Tail FibersTail Fibers

Bacteriophages Viruses that infect

bacteria Tail and tail fibers

used like a syringe

Inject viral DNA into cell

ReproductionReproduction

Lytic Life Cycle

1.virus attaches to cell and injects DNA

2.use host cells organelles to make viral DNA and proteins.

3.New viruses are assembled in host cell.

4. Host cell breaks open and releases new viruses.

5. New viruses infect new cells.

ReproductionReproduction

Lytic Life Cycle (con’t)

Host cells die

Virulent virus use lytic cycle

Ex: HIV, Rabies, etc

ReproductionReproduction

Lysogenic Life Cycle

1. Viral DNA become part of the host cells DNA. (becomes a prophage)

2. Viral DNA replicates with host cells DNA

3. Replicated host cell contain viral DNA (becomes a provirus)

4. Host cell does not die

ReproductionReproduction

Lysogenic Life Cycle (con’t) Temperate viruses may enter lytic

cycle Provirus may become a permanent

part of the hosts DNA Ex:chickenpox

Lytic & Lysogenic CyclesLytic & Lysogenic Cycles

Viral DiseasesViral Diseases

Causes disease in bacteria,plants, and animals

Viruses are specific to their hosts Symptoms are caused by…

Toxic parts (envelope) Cause cell to produce toxins Lysis of host cell

Results in fever and body aches

Viral DiseasesViral Diseases

Possible causes of cancer HPV (cervical cancer) Hepatitis B (liver cancer)

No treatment for viral diseases only the symptoms

Prevention Vaccines- weakened form of the

pathogen

Emergent DiseasesEmergent Diseases

Newly recognized diseases or diseases that have reemerged

New Diseases Swine Flu, Avain Flu, SARS,etc

Re-emergent Measles, Hanata Virus, Drug Resistant

TB

Disease TransmissionDisease Transmission

Direct Contact-kissing,sex,etc Fomites (indirect contact)-door

knobs,keyboards,etc Droplet- sneezing, coughing Airborne- droplets or dust Vector- animals like mosquitoes,

rats, dogs,etc

Important ScientistsImportant Scientists

3 scientists made major breakthrough in the fight against disease and infections. Alexander Fleming Louis Pasteur Robert Koch

Important ScientistsImportant Scientists

Alexander Fleming is credited for his discovery of penicillin, a very important antibiotic.

Louis Pasteur is credited for developing sterilization techniques to help kill pathogens.

Robert Koch is credited for developing steps to diagnose diseases.

Identifying PathogensIdentifying Pathogens

Koch’s Postulates1. Find and Isolate pathogen from

diseased animal or person.2. Grow pathogen in a lab.3. Infect a healthy animal.4. Isolate the pathogen from second

animal.