Lab 10 - Prokaryotes, Bacteria, Archaea, Gram Stain, Lab Terms

What is taxonomy

The science of classifying organisms based on shared characteristics

What is the correct order of taxonomy

Domain Kingdom Phylum Class Order Family Genus Species

Why do we use taxonomy

To show evolutionary relationships and organize classification

How must genus and species be written

Must be italicized or underlined

What is a species

A group that can reproduce and produce viable offspring

What is the binomial name for humans

Homo sapiens

What is the domain Bacteria

Domain of prokaryotes that have peptidoglycan in cell walls

What is the domain Archaea

Domain of prokaryotes that live in extreme environments and lack peptidoglycan

What is the domain Eukarya

Domain that includes all eukaryotic organisms

What makes prokaryotes unique

They have circular DNA no membrane bound organelles and no nucleus

What kind of reproduction do prokaryotes use

Binary fission

What is binary fission

Asexual reproduction that creates genetically identical clones

Why do prokaryotes still evolve if they clone

Horizontal gene transfer adds variation

What are plasmids

Small circular pieces of DNA separate from the chromosome

What are pili

Structures used for attachment or conjugation

What are endospores

Dormant resistant structures that survive harsh environments

What environment do methanogens live in

Anaerobic swamps or bogs

What gas do methanogens produce

Methane

Why are methanogens obligate anaerobes

Oxygen is toxic to them

Where do halophiles live

Very salty environments like the Dead Sea

What molecule produces the color in halophiles

Bacteriorhodopsin

Do halophiles perform photosynthesis

No they do photophosphorylation without chlorophyll

Where do thermoacidophiles live

High temperature and low pH environments

What is an example of a thermoacidophile

Picrophilus grows at pH less than 1

What is peptidoglycan

A cell wall component unique to bacteria

Why do we gram stain

To classify bacteria by their cell wall composition

What is a gram positive bacteria

Bacteria with a thick peptidoglycan layer that stains violet or purple

What is a gram negative bacteria

Bacteria with a thin peptidoglycan layer that stains red or pink

Why are gram negative bacteria more resistant to antibiotics

They have an outer membrane that blocks drugs

What is chemotaxis

Movement toward or away from chemicals

What is phototaxis

Movement toward or away from light

What are bacterial flagella made of

Flagellin protein

What does bacillus mean

Rod shaped bacteria

What does coccus mean

Spherical bacteria

What does spirillum mean

Corkscrew shaped bacteria

What does diplo indicate

Bacteria arranged in pairs

What does staphylo indicate

Bacteria arranged in clusters

What does strepto indicate

Bacteria arranged in chains

What is conjugation

DNA transferred between bacteria through a pilus

What is transformation

DNA absorbed from the environment

What is transduction

DNA transferred by bacteriophages

What is an obligate aerobe

Requires oxygen to grow

What is an obligate anaerobe

Oxygen is toxic to them

What is a facultative anaerobe

Can grow with or without oxygen

What is mutualism

Both organisms benefit

What is commensalism

One organism benefits one is unaffected

What is amensalism

One is harmed one is unaffected

What is parasitism

One benefits at the expense of the host

What are proteobacteria

The largest diverse bacterial phylum

What are alpha proteobacteria

Includes Rhizobium nitrogen fixing mutualist with plants

What are beta proteobacteria

Includes Neisseria gonorrhoeae causes gonorrhea

What are gamma proteobacteria

Includes E coli Vibrio cholerae Salmonella Legionella

What are delta proteobacteria

Includes slime producing myxobacteria and Bdellovibrio predators

What are epsilon proteobacteria

Includes Helicobacter pylori causes ulcers and Campylobacter

What is Chlamydia

Obligate intracellular parasite with no peptidoglycan in cell wall

What are spirochetes

Spiral bacteria with internal flagella include syphilis and Lyme disease

What is cyanobacteria

Photosynthetic bacteria that contain chlorophyll a

What is a heterocyst

Specialized structure for nitrogen fixation in cyanobacteria

What are gram positive bacteria

Bacteria with thick peptidoglycan walls include Bacillus and Clostridium

What are mycoplasmas

Smallest bacteria with no cell wall and cause walking pneumonia

What are the steps of a gram stain

Crystal violet iodine alcohol safranin

What does crystal violet do

Primary stain

What does iodine do

Fixes crystal violet to peptidoglycan

What does alcohol do in a gram stain

Decolorizes gram negative and removes outer membrane

What does safranin do

Counterstains gram negative pink

What is an antiseptic

Chemical used on living tissue to inhibit growth

What is a disinfectant

Chemical used on surfaces to kill microbes

What is a streak plate used for

To isolate individual colonies

What is a zone of inhibition

Clear area around an antibiotic where bacteria do not grow

Why do bacteria form colonies on agar

Each colony is a clone of a single cell