Bio2 Chapter 23:Prokaryotes, Bacteria and Archaea

Bacteria and Archaea are Prokaryotic, what does that mean?

They lack a membrane bound nucleus

Be able to draw and interpret the phylogenetic tree of the 3 domains of life: Bacteria, Archaea and Eukarya

Common ancestor, bacteria split from archaea and eukarya, archaea and eukarya split.

Bacteria are ancient, diverse, abundant, and ubiquitous. What does that mean?

Oldest fossils are 3.5 billion years old, millions of bacterial species are likely, bacteria are found almost everywhere on the planet, there are 5 X 10^30 individuals estimated

The oldest fossils are from what domain of life

bacteria

How many species of bacteria have been named? How many are likely?

5000 named, millions likely

Where do prokaryotes live

almost everywhere on earth

How much of the earth's biomass is estimated to be prokaryotic?

10%

How deep in the ocean have prokaryotes been found?

10km below the surface and even under the ocean floor

What is the temperature range for prokaryotes?

from 0-121 degrees Celsius

What is meant by pathogenic bacteria?

Bacteria that can cause disease

What archaea pathogen affects humans?

Periodontis

Who is credited with the Germ Theory of Disease?

Robert Koch in the late 1800s

What are Koch's postulates?

1. The same pathogen must be present in every case of the disease.

2. The pathogen must be isolated from the diseased host and grown in pure culture.

3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.

4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

What caused the tremendous decline in mortality rates after 1900?

Sanitation measures

What is virulence and why is it important to humans?

Virulence is the ability of a bacteria to cause disease. It is important to humans because virulent bacteria can cause disease in humans and be be resistant to antibiotics.

When were antibiotics discovered?

1928, and were widespread in the 1940s

What has been the effects of the overuse of antibiotics?

Overuse has led to antibiotic-resistant strains of bacteria

What is meant by the word "extremophile"?

Bacteria can live in extreme environments, such as high salt, high or low temperature, high pressure

Name 3 ways researching extremophiles are important to biologists?

1) may help explain how life on earth began

2)can serve as a model organism for the search for extraterrestrial life

3)Enzymes found in bacteria help DNA research (sequencing)

Describe how bacterial species are described

Grown under specific condition

Temperature

Lighting

Substrate

Available food

increase abundance of individuals with specified conditions for study

What is an enrichment culture used for? What is its purpose?

Cells are sampled and grown under specific conditions to increase their abundance for study

How are bacterial species found using direct sequencing?

unique DNA sequences identify new species. This is the phylogenetic approach.

What are the steps for the process of direct sequencing?

Isolate part of the genome, sequence the genes, compare the sequence with the database. If the sequence significantly differs you may have a new species.

Who discovered Archaea?

Carl Woese in the 1960s

How did Carl Woese redraw the Tree of Life?

He identified a 3 domain system rather than a 5 kingdom system.

Why did the 5 kingdom system fall out of favor?

The discovery of Archaea, which were more closely related to Eukaryotes than Bacteria.

Are archaea more closely related to bacteria or eukarya?

Eukarya

which are older, bacteria or Archaea?

Bacteria

Name 3 differences between gram-positive and gram-negative bacteria

Gram positive bacteria have a thick cell wall that stains purple and is made mostly of carbohydrates. Gram-negative bacteria have a thin layer of peptidoglycan and an extra phospholipid layer that doesn't absorb stain, so it appears pink.

What is the difference between autotropic and heterotrophic bacteria?

Their metabolism. Autotrophs make their own carbon-containing compounds and heterotrophs live by consuming compounds made by others.

Were the first bacteria thought to be autotropic or heterotropic?

Heterotrophic

What does a chemoorganotroph eat?

organic molecules

What does a chemolithotroph eat?

inorganic molecules

What does a photoautotroph eat?

Light

- Photophosphorylation

- Electrons to top of electron transport chain

What is the difference between bacteria and archaea?

Bacteria have peptidoglycan in their cell wall and archaea don't. Archaea are more similar to Eukaryotes.