Prokaryotes Flashcards
key difference between bacteria and archea
bacteria have cell walls made of peptidoglycan
s layer
An S-layer is a part of the cell envelope found in almost all archaea, as well as in many types of bacteria. It consists of a monomolecular layer composed of identical proteins or glycoproteins. This structure is built via self-assembly and encloses the whole cell surface.
anitbiotic function
antibiotics break the sugar bonds in the peptidoglycan wall
extremophiles
organisms that have been discovered that survive in conditions that were previously thought unable to sustain life
similarities to bacteria
both have a circular chromsome with compact dna
no nuclear membrane
no cell organelles
they have similar cell morphology
cell wall composition
cell wall composition varies
proteins, glycoproteins, polysaccharides or all of them.
some have no cell walls
a common feature is that none of them contain peptidoglycan.
common ancestors
archea and eukaryotes share a common ancestor, even though they look completely different
bacteria and bacteria are not closely related even though they look similar
pseudomurein
Pseudopeptidoglycan (also known as pseudomurein) is a major cell wall component of some Archaea that differs from bacterial peptidoglycan in chemical structure, but resembles bacterial peptidoglycan in function and physical structure.
it is structurally similar to peptidoglycan
a unique amino sugar forms the backbone. the linkages are not sensitive to lysozyme or penicillin.
cell membranes
they have unique cell membranes.
the lipid tail is not a fatty acid - they vary in structure.
an ether linkage bonds the fatty acids to glycerol.
the lipids can form bi or mono layers.
hypoxic conditions
Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level.
hami
a long pilli-like structure that works as a grappling hook.
they use this structure as a grappling hook to attach to surfaces or to each other.
archaella
unique flagella
for motility
what is the fastest organism on earth
a flagellated archael cell
LUCA
the last common ancestor
controversy of classification
linnean taxonomy and phylogeny can differ
phylogenetically related organisms may not share morphology/phenotype
discover that archea and bacteria were different
The scientific community was understandably shocked in the late 1970s by the discovery of an entirely new group of organisms – the Archaea. Dr. Carl Woese and his colleagues at the University of Illinois were studying relationships among the prokaryotes using DNA sequences, and found that there were two distinctly different groups. Those “bacteria” that lived at high temperatures or produced methane clustered together as a group well away from the usual bacteria and the eukaryotes. Because of this vast difference in genetic makeup, Woese proposed that life be divided into three domains: Eukaryota, Eubacteria, and Archaebacteria. He later decided that the term Archaebacteria was a misnomer, and shortened it to Archaea. The three domains are shown in the illustration above at right, which illustrates also that each group is very different from the others.
differences in dna as a function
differences in dna is a function of the number of mutations accumulated since the last common ancestor.
why arent archea sensitive to lysozyme
lysozyme is an enzyme that targets the backbone of the peptidoglycan in bacterial cell walls
in archea, the linkages that form the backbone are not sensitive to lysozyme
bacterial chromosome
a circular chromsome
compact dna
no nuclear membrane
called a nucleoid
extreme halophiles
can survive
archael cell growth
since they are prokaryotes they multiply by binary fission
why cant many archaeal cells be grown in a lab
because we are not able to recreate the odd and extreme conditions they usually live
archael metabolism
phototrophy
anaerobic
aerobic
or facultative anaerobes
hyperthermophile
an organism that thrives in extremely hot environments
methanogens
organisms that produce methane as a byproduct of metabolism in hypoxic conditions
