What are the three domains of life that share a common ansestor?
Bacteria, archaea, and eukaryota
What do ALL organisms have?
Plasma membranes and ribosomes, metabolic pathways, semi-conservative DNA replication, and DNA that encodes proteins.
Are prokaryotes monophyletic?
How do prokaryotes differ from eukaryotes?
All prokaryotes are unicellular. They divide by binary fission and NOT by mitosis, DNA is often circular, not in the nucleus and there is no membrane-enclosed organelles.
Before DNA sequencing, how were prokaryotes classified?
Based on phenotypic characters (shape, color, motility, nutrition, and cell wall structure
What do gram-positive bacterial tests mean?
Dense cell wall
What do gram-negative bacterial results mean?
Thin cell wall with outer membrane
What has whole genome sequencing revealed about prokaryotes?
Even distantly related prokaryotes sometimes exchange genetic material
How do prokaryotes exchange materials without reproducing?
Lateral gene transfer: transformation, conjugation, and transduction
How does lateral gene transfer affect making phylogenetic reconstructions?
It makes it difficult, especially among prokaryotes, it has also made it difficult to reconstruct relationships between major domains of life.
Why is the sequencing of ribosomal RNA (rRNA) genes useful for phylogenetic studies?
Because it was present in the common ancestor of all life, because all free-living organisms have rRNA, because lateral transfer of rRNA genes among distantly related species is highly unlikely and because rRNA has evolved slowly
Why does most prokaryote biodiversity remain unknown?
Because many have resisted the efforts to grow in pure culture. And because biologists are sequencing samples collected from the environment but many new sequences imply that there are THOUSANDS more prokaryotic species than we currently know about.