Chapter 22 Prokaryotes

Who created the first microscope to see bacteria?

Leeuwenhoek

What does a culture medium contain?

contains all the nutrients needed by the target microorganism, can be liquid (broth) or solid

What does a pure culture medium contain?

a laboratory culture containing a single species of microorganism

Cocci

Bacilli

Spirili

Staphylococci

cocci in groups/clusters

Streptococci

overlaps but is the round shape

Prokaryote structure

Plasma membrane, cytoplasm, double stranded DNA genome, ribosomes

What do prokaryotes not contain

No membrane bound organelles, no nucleus, no microtubules, ribosome “free”

Do bacteria contain peptidoglycan in the cell wall

Yes

Do Archaea contain peptidoglycan in the cell wall?

No

Where do the cells walls in prokaryotes lie?

the cell wall lies outside the plasma membrane and prevents lysis

What stain color does Gram positive bacteria give?

Purple

What stain color does Gram negative bacteria give?

Pink

How many periplasmic spaces are in gram positive bacteria?

One gap between cell wall and cell membrane

How many periplasmic spaces are in gram negative bacteria?

two gaps between cell membrane and cell wall(first gap) and a gap between cell wall and outer membrane(second gap)

What is the cell membrane in bacteria made up of?

Phospholipids

What is the outer membrane of gram negative bacteria made of?

Lipopolysaccharide 

What is the function of the Lipopolysaccharide layer(outer membrane)?

Is a toxic layer that resists drugs and the immune system

What is the slime layer on bacteria called?

Glycocalyx

What is the function of Glycocalyx?

Sticky carbs and proteins secreted from the cell wall that glues to surfaces and resists attacks from the immune system. It holds in moisture.

What are hair-like protein called?

Fimbriae (short pili)

What structure allows movement on prokaryotes

flagellum

What is taxis?

movement directed toward or

away from (+ or -) stimulus

What is Chemotaxis

Stimulus toward chemicals

Phototaxis

Stimulus toward light

Geotaxis(magneto taxis)

magnetic

Do prokaryotes have plasmids

Yes

Do plasmids add diversity?

Yes

Do Archaea contain a nucleus(nuclear envelope)

No

Do Archaea contain membrane bound organelles?

No

Archaea and Eukarya starting codons are methionine(AUG)

True

Do bacteria contain histones

No

Are histones present in archaea?

In some species

Are histones present in Eukarya

Yes

Bacteria and Archaea have circular chromosome

True

What are Archaea membranes formed by?

Glycerol skeleton with ether linkages

What are Extremophiles

Bacteria and archaea that are adapted to grow under extreme

conditions (e.g. deep see vent, heat, dry, cold, radiation, etc.)

Acidophiles

Live in conditions with a pH of 3 or below

Alkaliphiles

Live in conditions with a pH of 9 or above(basic solutions)

Thermophiles

Live in conditions with temperatures of 60–80 °C (140–176 °F)(extremely hot)

Psychrophiles

Live in extremely cold environments of temperatures of -15-10 °C (5-50 °F) or lower

Halophiles

Salt concentration of at least 0.2 M(high salt concentration)

Osmophiles

High sugar concentration

What are photoautotrophs energy source?

use energy from sunlight, and carbon from carbon dioxide.(plants)

What are photoheterotrophs energy source?

obtain their energy from light, but their carbon from organic compounds.

What are Chemoheterotrophs energy source?

obtain both energy and carbon from chemical sources.(humans and animals)

What are Chemolithoautotrophs energy source?

obtain their energy from inorganic compounds, and they build their complex molecules from carbon dioxide.

What is symbiosis?

two species living in close relationship

What is Parasitism?

– smaller parasite benefits at

expense of other species (host)

• incl. pathogens (cause disease)

What is commensalism?

one species benefits without any impact (good or bad) on other species

• Ex: most bacteria on our skin

What is mutualism?

– both species benefit from each other

• Ex: Rhizobium in legume roots get sugar & water; provide fixed N for plant

Why are chemoheterotrophic bacteria important?

are the most important decomposers on earth

Secreted enzymes hydrolyze dead material or wastes

What bacteria caused the Oxygen revolution?

Cyanobacterial photosynthesis and are a major producer of oxygen to this day!

What does carbon fixation produce?

Sugar

In prokaryotes do they produce sexually or asexually?

Asexually

What type of asexual reproduction do prokaryotes do?

Through Binary fission: does not provide genetic diversity.

Where does genetic diversity come from in prokaryotes?

Horizontal gene transfer

Prokaryotes have a higher cell division rate and short generation times

True

What are the 3 types of horizontal gene transfer?

Conjugation, Transduction, Transformation

What is transformation?

From the environment, it is when the cell takes up prokaryotic DNA directly from the environment.

The DNA may remain separate as plasmid DNA or be incorporated into the host genome.

What is transduction?

a bacteriophage injects DNA into the cell that contains a small

fragment of DNA from a different prokaryote.

By Bacteriophages.

What is conjugation?

cell-to-cell contact: DNA is transferred from one cell to another via a pilus that connects the two cells.

What do endospores do?

survive heat, drought for years. They are indestructible(Ex: Tetanus and anthrax)

Domain Archaea

Includes extremophiles and methanogens. Do not cause disease in humans

Domain Bacteria: Proteobacteria

Gram negative(stain pink): includes nitrogen fixing bacteria. Includes gastrointestinal pathogens

Examples of Proteobacteria

Cholera, salmonella, and Escherichia coli

Domain Bacteria: Chlamydia

Gram negative(pink): are all endoparasites (live within animal cells). Example: Chlamydia in humans causes STD

Domain bacteria: Spirochetes

Spiral shape, free-living but include disease causing pathogens. Examples: Syphilis and Lyme disease

Domain Bacteria: Cyanobacteria

Oxygen generating photosynthesis. Some are nitrogen fixing. Cyanobacteria blooms are toxic

Domain Bacteria: Gram Positive Bacteria

include many decomposers in soils. Includes many pathogens.

Examples of Gram positive bacteria

Anthrax, tetanus, Staph(MRSA), strep

What do pathogenic bacteria cause?

Infections produce bacterial poisons

What is Produced by both gram-negative and gram-positive bacteria

Exotoxins(excreted)

What are Endotoxins?

are toxic outer membranes of some gram negative bacteria Ex: salmonella

Antibiotics

kill bacteria cells but not eukaryotic cells

Example of antibiotics

Penicillin: affects peptidoglycan cell wall

What causes bacteria to resist more and more drugs?

Horizontal gene transfer

What is Microbial bioremediation?

is the use of prokaryotes (or microbial

metabolism) to remove pollutants

• Some bacteria can remove toxic metals

• Some can transform toxic mercury into nontoxic forms