Archaea Flashcards
Which of the following are characteristics of archaeal cell membranes that probably help them survive at very high temperatures?
Choose one or more:
The ether bond is stronger than the corresponding ester bond found in bacteria, serving to make these molecules more heat resistant. The terpenoids may also contain cyclopentane rings, which confer added stability. The most heat-loving (thermophilic) members of the Archaea domain contain terpenoids that are linked at the ends of the tails to form a membrane monolayer. This conformation allows the cells to thrive at temperatures that far exceed boiling!
What are sensory rhopsoin 1 and 2
serve as sensory devices involved in phototaxis. These proteins each have seven alpha helices containing retinal. When the sensory rhodopsins absorb light, they signal the cell to swim using its flagella.
Which protein(s) aggregate in complexes called purple patches?
the purple pigment bacteriorhodopsin, which is deposited in dense patches in the cell membrane, forms patches of purple membrane.
What do bacteriorhodopsin and halorhodopsin do?
The result of proton transfer by bacteriorhodopsin is the generation of a proton motive force that can run a proton-driven ATP synthase that generates energy as ATP. Because chloride is negatively charged, chloride transport across halorhodopsin contributes to maintaining the proton motive force.
Archaea share similar _____ with eukaryotes.
transcription factors and histones
The ether links found between glycerol and the isoprene units of the archaeal membrane are
______ stable than the ester links found in bacterial and eukaryotic phospholipids. Breaking an ester linkage requires
______energy than breaking an ether linkage.
more, less
Which is the most distinctive cellular structure found in archaea?
The most distinctive structure of archaea is their membrane. The membrane lipids of archaea differ greatly from those of bacteria and eukaryotes, with the exception of a few thermophilic bacteria. Unique characteristics include the presence of L-glycerol rather than D-glycerol, ether linkages, isoprenoid chains, and, in some hyperthermophiles, the ends of side chains are linked covalently either to each other or to a lipid on the opposite side of the membrane. Most features of archaeal lipids increase lipid stability in extreme environments such as high temperatures or extreme acidity.
Hyperthermophiles grow at extreme temperatures and therefore possess unique enzymes to stabilize their DNA structure. Which of the following choices includes the correct enzyme and its chromosomal function found in hyperthermophiles?
reverse gyrase; positive supercoiling of DNA
S-layers
protect from osmotic stress, is the sole cell wall component and varies in composition depending on the environmental conditions of the organism’s habitat
Why are archaea considered to be their own domain
They are the most primitive type and known as the ancient microbes found in extreme niches such as hydrothermal vents, higher salt concentration, high temperature, and pressure etc. They also have morphological differences from bacteria and eukarya which allows them to thrive in such extreme conditions.
They have some structures not found in any other domain but common between all of them like isoprenoid l-glycerol ethers
they share traits with eukarya and prokarya that suggest a common ancestor
but carl worse compared fences found differences in archaea DNA and key differences, unique traits like ribosomal RNA
General Properties
Inclusion bodies, similar protein content to bacteria, protein cytoskeleton, no sporulation and no nucleus only nucleoid
Distinctive Properties
distinct genome structure, ether-linked membrane lipids, cell wall, extreme enviros. , size: 0.5-5 um, plasma membrane.
Archaella
Archaeal motility structure
*Simpler than flagella
*Uses ATP rather than PMF
*Made of glycoproteins archaellins
*Anchored to the cell
*Archaella (singular: archlaellum) rotate like flagella (eukaryotes have whip-like flagella)
gene structure
promoter (similar to eukaryotes) , TATA box, BRE and formation of pre-initiation complex.
i.e: bacteria-like regulators must interact with a scaled-down version of a eukaryotic transcription machinery and gene structure.
Chromatin Structure
histones tetramers(octamer)
Allows stacking of units/superhelix (not in eukaryotes)
->Histone tails
