Unique Aspects of Archaea cell biology

Question 1

dimilsrity between archaea and eukaryotes

Answer 1

-DNA-related and biological processes such as chromosome strucutre, replication transcription and translation

Question 2

similarities between bacteria and archaea

Answer 2

-prokaryotes
-usually single cell
-overall similar sizes and morphologies

Question 3

comparison of bacteria and eukarya

Answer 3

bacteria - ester linked lipids -archea - ether linked
bacteria - lipids are fatty acids archara - isoprenoid
-archaea lipids contain side branches and rings
-some archaea produce transmembrane phospholipids (lipid monolayer) but tails are joined
-unique membrane strcutre is thorught ot be improtant for its ability to survive in harsh environments

Question 4

monolayer membrane of archea

Answer 4

Question 5

cell walls of archaea

Answer 5

-dependent on the environmental niche
-for most of archara proteinaceous S-layer act as the cell wall
-other archaea use variable proteinaceous or carbohydrate structures similiarily to bacteria
- A few archea lack a cell wall or cell envelope is not yet characterized or understood
-rare archaea have a second membrane (nothing like LPS containing of gram (-) bacteraia

Question 6

pseudomurein

Answer 6

-pseudomeuron is remarkably similar to peptidoglycan
-no D-AA, different sugar linkage, MurNac replace with acetylaosainuronic acid
-beta 1-3 linkages not 1-4
-thought to have evolved indepdently from peptidoglycan even though they have all these similarityies (convergent evolution)

Question 7

hamus

Answer 7

-appendage of archaea
-fix cells to a surface or to other cells to mediate biofilm formation
-proteinaceous “grappling hook”

Question 8

archaea motility

Answer 8

-flagellum like apparatus but functionally evolutionary distinct
-can be chemotactic but mainly motor drives movement
-fewer proteins than flagellum
-driven by ATP hydrolysis
-filament built from inside out (flagellum from outside in)
-related to type IV pilus
-swim slower than bacteria

Question 9

holoquadratum walsbyi

Answer 9

-extreme halophile found in hyper saline lakes
-commonly produces PHA granules and gas vessicles
-very thin swuares and high SA/V ratio - unique

Question 10

asgard archaea

Answer 10

-found in anaerobic marine sedements
-this lineage of archaea is most closely related to eukarya
-some phylogenetic trees place eukarya within archaea lineage
-contain many eukaryote specific genes (cytoskeleton and vesciular trafficking)
-some aspects of eukaryotic cell biology probably evolved before the first eukaryote because archaea carry these genes