Chapter 10: Archaea

What are the three domains of life?

Bacteria, Archaea, Eukarya

what are the domains based on?

differences in DNA gene sequences

What has systematics of eukaryotes historically been based on?

mainly based on differences in morphology and physiology

why can't microbial systematics be based on the same criteria?(referring to eukarea historically systematics)

microbes have morphology, but they have very little variation in shape

what was microbial systematics based on until 1970s

biochemical testing

What are systematics of organisms based on now?

molecular sequences like DNA - tells us more

what are the strengths of this new system?(using DNA to classify)

every living thing has DNA so it is possible to compare them
DNA sequences tell us about the evolutionary history
more accurate becAuse material is abundant
allows us to classify microbes that can't be cultured

How is a eukaryotic species defined?

refers to species that reproduce sexual

Why can't this concept be used for microbial species?(refering to how to identify eukarea)

they don't produce sexually, and they can exchange genes with distantly related species

What is the eocyte hypothesis?

states that eukaryotes originated within the archaea, not a sister group to it

Who was the scientist that discovered organisms known as prokaryotes are actually two different branches of life - archaea and bacteria?

Carl Woese

What gene was used for the original phylogenic work on determining bacterial taxonomy?

16S rRNA gene

Are all archaea extremophiles?

Almost all are known as extremophiles. But most archaea are not extremophiles. Hyperthermophiles, Halophiles, Methanogens

How do bacteria and archaea differ?

archaea have different phospholipids on their membrane
Archaea have no peptidoglycan in their cell walls
Their flagella differ

What metabolic ability is only exhibited by archaea and never by bacteria?

Archaea have the ability to produce methane (methanogen)

What common chemical compound cannot be utilized by archaea for energy production?

glucose

How are archaea beneficial?

Benefit industry and technology, source of enzymes that work at extreme temperatures and pH
Methanogens are used in solid waste treatment in wastewater treatment plants