Chapter_4_Archaeal Cell Structure Flashcards
Which cell shapes are observed in members of both Bacteria and Archaea? Which are unique to bacteria? Which to archaea?
- Both: cocci and rods
- Unique to archaea: branched and flat
Unique to bacteria: spirochetes and mycelial
Archaea was first defined as a distinct taxon by comparisons of ribosomal RNA sequences. Identify two other molecules that could be used to determine if a microbe having a prokaryotic morphology is a bacterium or an archaeon.
- Peptidoglycan: present in bacteria, absent in archaea
Lipids: ester linked in bacteria, ether linked in archaea
Identify three features that distinguish archaeal plasma membranes from those of bacteria.
- Contains ether linkages instead of ester linkages
- Contains hydrocarbon chains of isoprene instead of fatty acids
L glycerol instead of D glycerol
Both bacteria and archaea can have S-layers. How does their use within the cells differ?
- Archaea s-layer is primary component of cell wall
Archaea s-layer is directly attached to plasma membrane
Archaea have some features similar to bacteria and some similar to eukaryotes. Based on what you have just read in this section, provide two examples that illustrate the similarity of archaea to bacteria; list two examples of their similarity to eukaryotes.
Bacteria
- Similar rRNA size to bacteria
- Both ribosomes are 70s
Eukarya
- Histone proteins in nucleoid
Proteins similar
What observations about cannulae and hami suggest that they allow archaeal cells to adhere to surfaces, including other cells?
- Cannule allows daughter cells to remain connected after cell division
Hami are hooks that allow attachment to cell surfaces
List three aspects of archaella and their motility that are similar to bacterial flagella and their motility.
- Move through propeller rotation
- Allow anchoring to membrane
- Protein based filaments
