`Microbiology

Adolf Mayer

Adolf Mayer

put sick tobacco sap into healthy tobacco plants, made them sick too, after assuming it was bacteria behind it, he tested it and found something smaller was behind the disease

Wendell Stanley

isolated the tobacco mosaic virus and determined that a virus caused the disease, NOT poison or bacteria

Virus

A nonliving particle made up mostly of a protein coat and nucleic acid (DNA or RNA, NEVER BOTH)

3 Main traits of Viruses

Extremely Small (need Electron microscope to observe), very simple shape and structure, small host range

Why can't a light microscope be used to observe viruses?

They are too small and viruses cannot be caught in filters that isolate bacteria

Capsid

Protein coat that surrounds and protects the DNA/RNA in a Virus

Envelope

• An additional nucleic acid protection found in many animal-infecting viruses.

• made of lipids, proteins, and carbs found on the host cell’s membrane.

• has spikes to help identify and infect its host cell.

• blue spikey circle in the image

What does a Virus' shape indicate?

The type of cells they infect ex. rod, polyhedral, space craft, or round

Host Range

The amount or extent of organisms/cells that a virus can infect

Why do Virus's need to infect host cells?

The can only way they can "reproduce" is by infecting a host cell to make more viruses

Virus Reproduction

known as VIRAL REPLICATION because: they asexually reproduce

they don’t reproduce by themselves, they have the host cell do it for them

How does an envelope help viruses?

Specific proteins in the virus envelope and cell membrane bond, lock, and key fit. The envelope is made of the same stuff as the cell membrane, so the cell does not defend itself.

Animal Viral replication

A virus merges with the host cell membrane like endocytosis, and viral DNA takes over the cell and makes it make more viruses, released through a process like endocytosis

What happens when a virus injects DNA into the host cell?

It takes over the functions of the cell by making the cell make more viruses like it makes protein (protein synthesis)

What 2 things happen when a virus injects RNA into the host cell?

RNA used as template for replication and mRNA is used by ribosomes to make Viral Proteins OR RNA → DNA→ DNA joins cell genome

Retrovirus

• RNA used as template for replication

• Newly made viral DNA incorporated into cell genome.

Bacteriophage

A virus that infects bacteria (usually capsid only)

• lytic or lysogenic cycle

Lytic Cycle

Immediately takes over host cell, replicates viruses, lyses and makes the viruses go flying

Lysogenic Cycle

Slow takeover of the host cell, hyjacks the DNA and makes it behave normally, Viral DNA replicated along with the cell

What happens when an enzymatic stimulus occurs?

The Viral DNA detaches from host cell DNA and lytic cycle is then activated (Lysogenic -> Lytic)

How are viruses fought off?

No medicine or cure, body has to kill all the infected cells

How are Viruses prevented?

Once your body fights off the virus once, it makes antibodies against that virus for the future so you can fight it off easily

Viroids

virus-like particles that infect plants (infectious RNA molecules)

Prions

bits of virus particles that infect animals

Eubacteria and Archaebacteria are ____________.

Prokaryotes

Basic Bacteria traits

• No nucleus (prokaryote)

• cell membrane but no membrane bound organelles

• ribosomes for making proteins

• has pilli

Strains/Types

how the bacteria uses energy

5 strains of Bacteria

Heterotrophs, photoheterotrophs, autotrophs, chemoautotrophs, and decomposers

Heterotrophs

have to consume other organisms for energy

Photoheterotrophs

can perform Photosynthesis but must also eat others for energy

Photoautotrophs

make their own food from sunlight (photosynthesis)

Chemoautotrophs

make their own food from chemicals

Decomposers

digest dead organisms and recycle nutrients for others

3 Ways bacteria breaks down their energy?

Obligate Aerobes, Obligate Anaerobes, and Facultative Anaerobes

Obligate Aerobes

NEED to use oxygen to digest food

Obligate Anaerobes

NEED to live without oxygen (killed by oxygen)

Facultative Anaerobes

can live with or without oxygen

2 kingdoms of bacteria

Eukarya (Eubacteria) and Archaea (Archaebacteria)

Archaebacteria

bacteria that lives in very HARSH environments, no peptidoglycan

Eubacteria

bacteria found everywhere, contains peptidoglycan

Carbohydrate Peptidoglycan

protein + sugar (carb - sugar, Peptidoglycan - protein)

4 subgroups of Archaebacteria

Methanogens, Thermoacidophiles, Extreme Halophiles, and Chemosythesizers

Methanogens

produce methane gas "swamp gas" (found in digestive system)

Thermoacidophiles

live in hot(thermo - heat), acidic(acido - acid) waters

Chemosynthesizers

use inorganic compounds for energy (ex. hydrogen sulfide)

Extreme Halophiles

live in extremely salty(hal - salt) conditions

Subgroups of Eubacteria

gram-positive and gram-negative

Gram-positive

have thick Peptidoglycan cell walls that stain purple

Gram-negative

Lipid layer surrounding think peptidoglycan wall cell wall and stains pink

Gram staining

a type of dye that reacts with the peptidoglycan cell walls of bacteria purple in gram-positive because it reacts with protein and sugar, pink in gram-negative because it reacts fat and sugar

What organelles do bacteria lack besides Nucleus?

Mitochondria, Chloroplasts, ER, and Golgi (mitochondria and chloroplasts may me embedded into membrane but not inside of it)

3 Shapes of bacteria

coccus/cocci, bacillus/bacilli, spirillum/spirilli

Cocci/Coccus

Sphere-shaped, sometimes in clumps or chains

Bacilli/Bacillium

rod-shaped, usually forms chains, may have flagella to move

Spirilli/Spirillum

spiral-shaped

How does bacteria reproduce?

Binary Fission

What do bacteria do in harsh conditions?

They form endospores with thick falls and some cytosol and dna

How can bacteria exchange genetic material (DNA)

Conjugation, transformation, and transduction

Conjugation

Bacteria forms cytoplasm bridge between 2 cells and DNA can transfer

Transformation

Bacteria collects free floating DNA from dead bacteria cells

Transduction

Virus takes some bacteria dna with it, and it comes with it into the new bacteria that the virus infects

2 ways bacteria can create infection in humans

• Uses human cells and tissues as food (ex. Mycobacterium tuberculosis)

• releases toxins that interfere with cell activities

What can be taken to fight bacteria?

Antibiotics

3 ways to control bacterial growth

Sterilization by heat, most bacteria dies in high temperatures after a while, disinfectants, and low temperature food storage

Louis Pasteur

composed the Germ Theory of Infectious Disease - diseases are created by microorganisms called pathogens

Koch (Koch's postulates)

Several rules for bacteria

• Pathogens are only found in dead organisms

• Pathogens should be grown in pure culture

• Pathogens cause the same disease no matter the host

• Pathogens must be isolated in order to accurately asses symptoms

Protists

Kingdom - Protista

Eukaryotes

3 Categories:

Protozoans, Algae, and Fungi-Like

Protozoans

animal-like protists

Algae

plant-like protists

Unicellular

One cell

Multicellular

Multiple cells

Fungi-like

some Molds

2 Fungi-like categories

Slime mold and Water Mold

Slime mold

alternates between two stages

Water mold

thrive on dead and dying stuff in water (some are plant parasites)

4 Categories of Protozoans

Sarcodines, Zooflagellates, Cilliates, and Sporozoans

Sarcodines (Sarcodinas)

• move by extending loves of cytoplasm called pseudopods

Zooflagellates

• move by using their flagella

Ciliates

• move and eat using Cilia

Sporozoans

spore-forming parasites

Unicellular Algae

one cell (in algae)

Dinoflagellates

has 2 flagella that spin the cell thru salt water

Diatom

has a glass like cell wall made of silica

Euglena

has flagella but no cell well

Multicellular Algae

more than 1 cell (algae)

Rhodophyta

red algae

Phaeophyta

brown algae

Protozoans vs Animals

protozoans are unicellular

Taxon

group or level of organization into which organisms are classified